An infectious disease is a clinically evident human disease resulting from the presence of pathogenic microbial agents, like pathogenic viruses, pathogenic bacteria, fungi, protozoa, multicellular parasites, and prions. To be considered an infectious disease, such pathogens are known to be able to cause this disease.In an infection, the infecting organism seeks to utilize the host's resources to multiply, and the pathogen, interferes with the normal functioning of the host.
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Oropouche fever is a tropical viral infection, a zoonosis similar to dengue fever, transmitted by biting midge (species Culicoides paraensis) and mosquitoes from the blood of sloths to humans. It occurs mainly in the Amazonic region, the Caribbean and Panama. The disease is named after the region where it was first described and isolated at the Trinidad Regional Virus Laboratory, in 1955, the Oropouche River in Trinidad and Tobago and is caused by a specific arbovirus, the Oropouche virus (OROV), of the Bunyaviridae family.
OROV was first described in Brazil in 1960, isolated from the blood of a sloth (Bradypus tridactylus) captured in the rain forest during the construction of the Belém-Brasília Highway. The Ochlerotatus serratus mosquito was implicated as a possible vector, because OROV was found in their blood too.
According to Nunes et al. (2005), "the OROV genome consists of 3 partite, single-stranded, negative-sense RNAs, named large (L), medium (M), and small (S) RNA. These RNAs are predicted to encode a large protein (L: polymerase activity), viral surface glycoproteins (Gc and Gn), and nonstructural NSM protein, as well as both nucleocapsid (N) and NSS proteins. Complete
Shigellosis, also known as bacillary dysentery or Marlow Syndrome, in its most severe manifestation, is a foodborne illness caused by infection by bacteria of the genus Shigella. Shigellosis rarely occurs in animals other than humans and other primates like monkeys and chimpanzees.
The causative organism is frequently found in water polluted with human feces, and is transmitted via the fecal-oral route. The usual mode of transmission is directly person-to-person hand-to-mouth, in the setting of poor hygiene among children.
Symptoms may range from mild abdominal discomfort to full-blown dysentery characterized by cramps, diarrhea, fever, vomiting, blood, pus, or mucus in stools or tenesmus. Onset time is 12 to 96 hours, and recovery takes 5 to 7 days.
Infections are associated with mucosal ulceration, rectal bleeding, and drastic dehydration. Reiter's disease and hemolytic uremic syndrome are possible sequelae that have been reported in the aftermath of shigellosis.
Shigella can be transmitted through food, including salads (potato, tuna, shrimp, macaroni, and chicken), raw vegetables, milk and dairy products, and meat. Contamination of these foods is usually through the fecal-oral
The species Reston ebolavirus is a virological taxon included in the genus Ebolavirus, family Filoviridae, order Mononegavirales. The species has a single virus member, Reston virus (RESTV). The members of the species are called Reston ebolaviruses. The name Reston ebolavirus is derived from Reston (the town in Virginia, USA, in which Reston virus was first discovered) and the taxonomic suffix ebolavirus (which denotes an ebolavirus species). Reston ebolavirus is pronounced ‘rɛstən iːˌboʊlə’vɑɪrəs (IPA) or res-tuhn ee-boh-luh-vahy-ruhs in English phonetic notation. According to the rules for taxon naming established by the International Committee on Taxonomy of Viruses (ICTV), the name Reston ebolavirus is always to be capitalized, italicized, never abbreviated, and to be preceded by the word "species". The names of its members (Reston ebolaviruses) are to be capitalized, are not italicized, and used without articles. The virus emerged in a primate quarantine facility in Reston, VA. Unlike other strains of the Ebola virus, this strain was confined and only lethal to primates (monkeys). It did, however, exhibit a trait not previously found with other strains: it was capable of being
Omphalitis is the medical term for infection of the umbilical cord stump in the neonatal newborn period. While currently an uncommon anatomical location for infection in the newborn in the United States, it has caused significant morbidity and mortality both historically and in areas where health care is less readily available.
The current incidence in the United States is somewhere around 0.5% per year. There does not appear to be any racial or ethnic predilection.
Like many bacterial infections, omphalitis is more common in those patients who have a weakened or deficient immune system or who are hospitalized and subject to invasive procedures. Therefore, infants who are premature, sick with other infections such as blood infection (sepsis) or pneumonia, or who have immune deficiencies are at greater risk. Infants with normal immune systems are at risk if they have had a prolonged birth, birth complicated by infection of the placenta (chorioamnionitis), or have had umbilical catheters.
Clinically, neonates with omphalitis present within the first two weeks of life with signs and symptoms of infection (cellulitis) around the umbilical stump (redness, warmth, swelling, pain), pus
A primary central nervous system lymphoma (PCNSL), also known as microglioma and primary brain lymphoma, is a primary intracranial tumor appearing mostly in patients with severe immunosuppression (typically patients with AIDS). PCNSLs represent around 20% of all cases of lymphomas in HIV infections (other types are Burkitt's lymphomas and immunoblastic lymphomas). Primary CNS lymphoma is highly associated with Epstein-Barr virus (EBV) infection (> 90%) in immunodeficient patients (such as those with AIDS and those iatrogenically immunosuppressed), and does not have a predilection for any particular age group. Mean CD4+ count at time of diagnosis is ~50/uL. In immunocompromised patients, prognosis is usually poor. In immunocompetent patients (that is, patients who do not have AIDS or some other immunodeficiency), there is rarely an association with EBV infection or other DNA viruses. In the immunocompetent population, PCNSLs typically appear in older patients in their 50's and 60's. Importantly, the incidence of PCNSL in the immunocompetent population has been reported to have increased more than 10-fold from 2.5 cases to 30 cases per 10 million population. The cause for the
Adenovirus infections most commonly cause illness of the respiratory system; however, depending on the infecting serotype, they may also cause various other illnesses and presentations.
Besides from respiratory involvement, illnesses and presentations of adenovirus include gastroenteritis, conjunctivitis, cystitis, and rash illness. Symptoms of respiratory illness caused by adenovirus infection range from the common cold syndrome to pneumonia, croup, and bronchitis. Patients with compromised immune systems are especially susceptible to severe complications of adenovirus infection. Acute respiratory disease (ARD), first recognized among military recruits during World War II, can be caused by adenovirus infections during conditions of crowding and stress.
Pharyngoconjunctival fever is a specific presentation of adenovirus infection, manifested as:
It usually occurs in the age group 5-18. It is often found in summer camps and during the spring and fall in schools. In Japan, the illness is commonly referred to as "pool fever" as it is often spread via public swimming pools.
Although epidemiologic characteristics of the adenoviruses vary by type, all are transmitted by direct contact,
Staphylococcal scalded skin syndrome, SSSS, also known as Pemphigus neonatorum or Ritter's disease, or Localized bullous impetigo is a dermatological condition caused by Staphylococcus aureus.
The syndrome is induced by epidermolytic exotoxins (exfoliatin) A and B, which are released by S. aureus and cause detachment within the epidermal layer. One of the exotoxins is produced by the bacterial chromosome, while the other is produced by a plasmid. (Bacterial plasmids are pieces of self-replicating DNA that often code for secondary characteristics, such as antibiotic resistance, and toxin production.) These exotoxins are proteases that cleave desmoglein-1, which normally holds the granulosum and spinosum layers together.
The disease presents with the widespread formation of fluid filled blisters that are thin walled and easily ruptured and the patient can be positive for Nikolsky's sign. Ritter's Disease of the Newborn is the most severe form of SSSS with similar signs and symptoms.
The clinical features were first described in 1878 by Baron Gottfried Ritter von Rittershain, who observed 297 cases among children in a single Czechoslovakian children's home over a 10-year period.
Ross River virus (RRV) is a small encapsulated single-strand RNA alphavirus endemic to Australia, Papua New Guinea and other islands in the South Pacific. It is responsible for a type of mosquito-borne non-lethal but debilitating tropical disease known as Ross River fever, previously termed "epidemic polyarthritis". The virus is suspected to be enzootic in populations of various native Australian mammals, and has been found on occasion in horses.
Taxonomically Ross River virus belongs to the virus genus Alphavirus, which is part of the family Togaviridae. The alphaviruses are a group of small enveloped single-strand positive-sense RNA viruses. RRV belongs to a subgroup of "Old World" (Eurasian-African-Australasian) alphaviruses, and is considered closely related to Sagiyama virus.
The virions themselves contain their genome in a protein capsid 700 Å in diameter. They are characterised by the presence of two glycoproteins (E1 and E2) embedded as trimeric dimers in a host-derived lipid envelope.
Because RRV is transmitted through mosquito vector it is considered an arbovirus, a non-taxonomic term for viruses borne by arthropod vectors.
In 1928 an outbreak of acute febrile arthritis
Onchocerciasis (/ˈɒŋkɵsɜrˈsaɪ.əsɨs/ or /ˈɒŋkɵsɜrˈkaɪ.əsɨs/), also known as river blindness and Robles disease, is a parasitic disease caused by infection by Onchocerca volvulus, a nematode (roundworm). Onchocerciasis is second in the world only to trachoma as an infectious cause of blindness. It is not the nematode, but its endosymbiont, Wolbachia pipientis, that causes the severe inflammatory response that leaves many blind. The parasite is transmitted to humans through the bite of a black fly of the genus Simulium. The larval nematodes spread throughout the body. When the worms die, their Wolbachia symbionts are released, triggering a host immune system response that can cause severe itching, and can destroy optical tissue in the eye.
The vast majority of infections occur in sub-Saharan Africa, although cases have also been reported in Yemen and isolated areas of Central and South America. An estimated 18 million people suffer from onchocerciasis, with approximately 270,000 cases of blindness related to the infection.
In 1915, Dr. Rodolfo Robles Valverde's study on patients with river blindness in Guatemala led to the discovery that the disease is caused by filaria of O.
Mononucleosis (also called "Mono", glandular fever, and, colloquially, the "kissing disease"), is a disease most commonly caused by the Epstein-Barr virus (EBV). EBV affects the lymphocytes which are white blood cells involved in the adaptive immune system. Mononucleosis can also be caused by cytomegalovirus (HCMV), a herpes virus most commonly found in body fluids. While CMV can cause mononucleosis, 85% of the cases are associated with EBV. The disease can be found in anyone but is most commonly contracted by adolescents and young adults ages 15–35.
Mononucleosis is associated with fatigue that can last up to several months. Symptoms are not usually felt until 4–7 weeks after exposure to EBV. While the disease is rarely fatal, occasionally the disease stays in the blood cells, affecting the person for the rest of his or her life. In every case, the person excretes the disease intermittently in saliva throughout their lives. In some cases, most commonly in teenage girls, the disease can lead to chronic fatigue. Research also shows that those infected with mononucleosis are more susceptible to contracting multiple sclerosis.
The main symptoms of mononucleosis include:
Bubonic plague is a zoonotic disease, circulating mainly among small rodents and their fleas, and is one of three types of bacterial infections caused by Yersinia pestis (formerly known as Pasteurella pestis), which belongs to the family Enterobacteriaceae. Without treatment, the bubonic plague kills about two thirds of infected humans within 4 days.
The term bubonic plague is derived from the Greek word βουβών, meaning "groin." Swollen lymph nodes (buboes) especially occur in the armpit and groin in persons suffering from bubonic plague. Bubonic plague was often used synonymously for plague, but it does in fact refer specifically to an infection that enters through the skin and travels through the lymphatics, as is often seen in flea-borne infections.
Bubonic plague—along with the septicemic plague and the pneumonic plague, which are the two other manifestations of Y. pestis—is generally believed to be the cause of the Black Death that swept through Europe in the 14th century and killed an estimated 25 million people, or 30–60% of the European population. Because the plague killed so many of the working population, wages rose and some historians have seen this as a turning point
Elephantiasis /ˌɛlɨfənˈtaɪ.əsɨs/ EL-i-fən-TY-ə-sis is a disease that is characterized by the thickening of the skin and underlying tissues, especially in the legs and male genitals. In some cases the disease can cause certain body parts, such as the scrotum, to swell to the size of a basketball. It is caused by filariasis or podoconiosis.
Elephantiasis leads to marked swelling of the lower half of the body.
Elephantiasis occurs in the presence of microscopic, thread-like parasitic worms such as Wuchereria bancrofti, Brugia malayi, and B. timori, all of which are transmitted by mosquitoes. However, the disease itself is a result of a complex interplay between several factors: the worm, the symbiotic Wolbachia bacteria within the worm, the host’s immune response, and the numerous opportunistic infections and disorders that arise. Consequently, it is common in tropical regions and Africa. The adult worms only live in the human lymphatic system. The parasite infects the lymph nodes and blocks the flow of lymph throughout the body; this results in chronic edema, most often noted in the lower torso (typically in the legs and genitals).
Alternatively, elephantiasis may occur in the
Metagonimiasis is a disease caused by an intestinal trematode, most commonly Metagonimus yokagawai, but sometimes by M. takashii or M. miyatai. The metagonimiasis causing flukes are one of two minute flukes called the heterophyids. Metagonimiasis was described by Katsurasa in 1911-1913 when he first observed eggs of M. yokagawai in feces (date is disputed in various studies). M. takahashii was described later first by Suzuki in 1930 and then M. Miyatai was describe in 1984 by Saito.
Stained Adult Fluke Causing Metagonimiasis
Metagonimiasis is most commonly caused by one of the two smallest flukes known to infect man, Metagonimus yokagawai, also called the Japanese fluke. More rarely, metagonimiasis can arise from infection with M. takahashii or M. miyatai. Recent studies analyzing the DNA of the three agents causing metagonimiasis found that DNA sequencing supports M. yokagawai and M. takahashii be placed in the same clade, and phylogenic tree analysis supports their genetic similarity. M. miyatai, however, was found to be more genetically distinct, and the authors concluded it should be nominated as a separate species. An additional study examining karyotype data on the three
Erysipelas (Greek ἐρυσίπελας—red skin; also known as "Ignis sacer", "holy fire", and "St. Anthony's fire" in some countries) is an acute streptococcus bacterial infection of the upper dermis and superficial lymphatics.
This disease is most common among the elderly, infants, and children. People with immune deficiency, diabetes, alcoholism, skin ulceration, fungal infections and impaired lymphatic drainage (e.g., after mastectomy, pelvic surgery, bypass grafting) are also at increased risk.
Patients typically develop symptoms including high fevers, shaking, chills, fatigue, headaches, vomiting, and general illness within 48 hours of the initial infection. The erythematous skin lesion enlarges rapidly and has a sharply demarcated raised edge. It appears as a red, swollen, warm, hardened and painful rash, similar in consistency to an orange peel. More severe infections can result in vesicles, bullae, and petechiae, with possible skin necrosis. Lymph nodes may be swollen, and lymphedema may occur. Occasionally, a red streak extending to the lymph node can be seen.
The infection may occur on any part of the skin including the face, arms, fingers, legs and toes, but it tends to favor the
Ghon's complex is a lesion seen in the lung that is caused by tuberculosis. The lesions consist of a calcified focus of infection and an associated lymph node. These lesions are particularly common in children and can retain viable bacteria, so are sources of long-term infection and may be involved in reactivation of the disease in later life.
In countries where cow milk infected with Mycobacterium bovis has been eliminated (due to culling of infected cows and pasteurization), primary tuberculosis is usually caused by Mycobacterium tuberculosis and almost always begins in the lungs. Typically, the inhaled bacilli implant in the distal airspaces of the lower part of the upper lobe or the upper part of the lower lobe, usually close to the pleura. As sensitization develops, a 1- to 1.5-cm area of gray-white inflammation with consolidation emerges, known as the Ghon focus. In most cases, the center of this focus undergoes caseous necrosis. Tubercle bacilli, either free or within phagocytes, drain to the regional nodes, which also often caseate. This combination of parenchymal lung lesion and nodal involvement is referred to as the Ghon complex. During the first few weeks there is also
Ankylosing spondylitis (AS, from Greek ankylos, stiff; spondylos, vertebrae), previously known as Bekhterev's disease, Bekhterev syndrome, and Marie-Strümpell disease, is a chronic inflammatory disease of the axial skeleton with variable involvement of peripheral joints and nonarticular structures. AS is a form of spondyloarthritis, a chronic, inflammatory arthritis where immune mechanisms are thought to have a key role. It mainly affects joints in the spine and the sacroiliac joint in the pelvis, and can cause eventual fusion of the spine.
It is a member of the group of the spondyloarthropathies with a strong genetic predisposition. Complete fusion results in a complete rigidity of the spine, a condition known as "bamboo spine". As of 2012, no cure is known for AS, although treatments and medications are available to reduce symptoms and pain.
AS has been suggested as the first recognized disease, having been distinguished from rheumatoid arthritis by Galen as early as the second century A.D.; however, skeletal evidence of the disease (ossification of joints and entheses primarily of the axial skeleton, known as "bamboo spine") was first discovered in an archaeological dig that
Foot-and-mouth disease or hoof-and-mouth disease (Aphthae epizooticae) is an infectious and sometimes fatal viral disease that affects cloven-hoofed animals, including domestic and wild bovids. The virus causes a high fever for two or three days, followed by blisters inside the mouth and on the feet that may rupture and cause lameness.
Foot-and-mouth disease is a severe plague for animal farming, since it is highly infectious and can be spread by infected animals through aerosols, through contact with contaminated farming equipment, vehicles, clothing or feed, and by domestic and wild predators. Its containment demands considerable efforts in vaccination, strict monitoring, trade restrictions and quarantines, and occasionally the elimination of millions of animals.
Susceptible animals include cattle, water buffalo, sheep, goats, pigs, antelope, deer, and bison. It has also been known to infect hedgehogs, elephants, llama, and alpaca may develop mild symptoms, but are resistant to the disease and do not pass it on to others of the same species. In laboratory experiments, mice and rats and chickens have been successfully infected by artificial means, but it is not believed that they
Rift Valley fever (RVF) is a viral zoonosis (affects primarily domestic livestock, but can be passed to humans) causing fever. It is spread by the bite of infected mosquitoes, typically the Aedes or Culex genera. The disease is caused by the RVF virus, a member of the genus Phlebovirus (family Bunyaviridae). The disease was first reported among livestock in Kenya around 1915, but the virus was not isolated until 1931. RVF outbreaks occur across sub-Saharan Africa, with outbreaks occurring elsewhere infrequently, but sometimes severely. In Egypt in 1977-78, several million people were infected and thousands died during a violent epidemic. In Kenya in 1998, the virus claimed the lives of over 400 Kenyans. In September 2000, an outbreak was confirmed in Saudi Arabia and Yemen). On 19 Oct 2011, a case of Rift Valley fever contracted in Zimbabwe was reported in a Caucasian female traveler who returned to France after a 26-day stay in Marondera, Mashonaland East Province during July and August, 2011 but later classified as 'not confirmed.'
The virus is transmitted through mosquito vectors, as well as through contact with the tissue of infected animals. Contact with infected tissue is
Scrapie is a fatal, degenerative disease that affects the nervous systems of sheep and goats. It is one of several transmissible spongiform encephalopathies (TSEs), which are related to bovine spongiform encephalopathy (BSE or "mad cow disease") and chronic wasting disease of deer. Like other spongiform encephalopathies, scrapie is caused by a prion. Scrapie has been known since the 18th century (1732) and does not appear to be transmissible to humans.
The name scrapie is derived from one of the clinical signs of the condition, wherein affected animals will compulsively scrape off their fleeces against rocks, trees or fences. The disease apparently causes an itching sensation in the animals. Other clinical signs include excessive lip smacking, altered gaits, and convulsive collapse.
Scrapie is infectious and transmissible among similar animals, so one of the most common ways to contain it (since it is incurable) is to quarantine and destroy those affected. However, scrapie tends to persist in flocks and can also arise apparently spontaneously in flocks that have not previously had cases of the disease. The mechanism of transmission between animals and other aspects of the biology
St. Louis Encephalitis is a disease caused by the Culex mosquito borne St. Louis Encephalitis virus. St. Louis encephalitis virus is related to Japanese encephalitis virus and is a member of the Flaviviridae subgroup. This disease mainly affects the United States. Occasional cases have been reported from Canada and Mexico.
The name of the virus goes back to 1933 when within five weeks in autumn an encephalitis epidemic of explosive proportions broke out in the vicinity of St. Louis, Missouri and the neighboring St. Louis County. Over 1,000 cases were reported to the local health departments and the newly constituted National Institute of Health was appealed to for epidemiological and investigative expertise. The previously unknown virus that caused the epidemic was isolated by the NIH team first in monkeys and then in white mice.
Mosquitoes, from the genus Culex, become infected by feeding on birds infected with the St. Louis encephalitis virus. Infected mosquitoes then transmit the St. Louis encephalitis virus to humans and animals during the feeding process. The St. Louis encephalitis virus grows both in the infected mosquito and the infected bird, but does not make either one
Aeromonas hydrophila is a heterotrophic, Gram-negative, rod-shaped bacterium mainly found in areas with a warm climate. This bacterium can be found in fresh or brackish water. It can survive in aerobic and anaerobic environments, and can digest materials such as gelatin and hemoglobin. Aeromonas hydrophila was isolated from humans and animals in the 1950s. It is the most well known of the six species of Aeromonas. It is resistant to most common antibiotics and cold temperatures.
Aeromonas hydrophila are Gram-negative straight rods with rounded ends (bacilli to coccibacilli shape) usually from 0.3 to 1 micrometer in width, and 1 to 3 micrometers in length. Aeromonas hydrophila can grow in temperatures as low as four degrees Celsius. These bacteria are motile by a polar flagellum.
Because of Aeromonas hydrophila’s structure, it is very toxic to many organisms. When it enters the body of its victim, it travels through the bloodstream to the first available organ. It produces Aerolysin Cytotoxic Enterotoxin (ACT), a toxin that can cause tissue damage. Aeromonas hydrophila, Aeromonas caviae, and Aeromonas sobria are all considered to be opportunistic pathogens, meaning they rarely
Rat-bite fever is an acute, febrile human illness caused by bacteria transmitted by rodents, rats in most cases, which is passed from rodent to human via the rodent's urine or mucous secretions. Alternative names for rat bite fever include streptobacillary fever, streptobacillosis, spirillary fever, sodoku, and epidemic arthritic erythema. It is a rare disease spread by infected rodents and can be caused by two specific types of bacteria. Most cases occur in Japan, but specific strains of the disease are present in the United States, Europe, Australia, and Africa. Some cases are diagnosed after patients were exposed to the urine or bodily secretions of an infected animal. These secretions can come from the mouth, nose, or eyes of the rodent. The majority of cases are due to the animal's bite. It can also be transmitted throughout food or water that is contaminated with rat feces or urine. Rats are not the only type of animal that can be infected with this disease. Others include weasels, gerbils, and squirrels. Household pets such as dogs or cats that are exposed to these animals can also carry the disease and infect humans. If a person is bitten by a rodent, it is important to
Panton-Valentine leukocidin (PVL) is a cytotoxin—one of the β-pore-forming toxins. The presence of PVL is associated with increased virulence of certain strains (isolates) of Staphylococcus aureus. It is present in the majority of community-associated Methicillin-resistant Staphylococcus aureus (CA-MRSA) isolates studied and is the cause of necrotic lesions involving the skin or mucosa, including necrotic hemorrhagic pneumonia. PVL creates pores in the membranes of infected cells. PVL is produced from the genetic material of a bacteriophage that infects Staphylococcus aureus, making it more virulent.
It was initially discovered by Van deVelde in 1894 due to its ability to lyse leukocytes. It was named after Sir Philip Noel Panton and Francis Valentine when they associated it with soft tissue infections in 1932.
Exotoxins such as PVL constitute essential components of the virulence mechanisms of S. aureus. Nearly all strains secrete lethal factors that convert host tissues into nutrients required for bacterial growth.
PVL is a member of the synergohymenotropic toxin family that induces pores in the membranes of cells. The PVL factor is encoded in a prophage—designated as
Lymphogranuloma venereum (also known as "Climatic bubo," "Durand–Nicolas–Favre disease," "Poradenitis inguinale," and "Strumous bubo") is a sexually transmitted disease caused by the invasive serovars L1, L2, L2a or L3 of Chlamydia trachomatis.
LGV is primarily an infection of lymphatics and lymph nodes. Chlamydia trachomatis is the bacterium responsible for LGV. It gains entrance through breaks in the skin, or it can cross the epithelial cell layer of mucous membranes. The organism travels from the site of inoculation down the lymphatic channels to multiply within mononuclear phagocytes of the lymph nodes it passes.
In developed nations, it was considered rare before 2003. However, a recent outbreak in the Netherlands among gay men has led to an increase of LGV in Europe and the United States. A majority of these patients are HIV co-infected.
LGV was first described by Wallace in 1833 and again by Durand, Nicolas, and Favre in 1913. Since the 2004 Dutch outbreak many additional cases have been reported, leading to greater surveillance. Soon after the initial Dutch report, national and international health authorities launched warning initiatives and multiple LGV cases were
Melioidosis is an infectious disease caused by a Gram-negative bacterium, Burkholderia pseudomallei, found in soil and water. It is of public health importance in endemic areas, particularly in Thailand and northern Australia. It exists in acute and chronic forms. Symptoms may include pain in chest, bones, or joints; cough; skin infections, lung nodules and pneumonia.
B. pseudomallei was previously classed as part of the Pseudomonas genus and until 1992, it was known as Pseudomonas pseudomallei. It is phylogenetically related closely to Burkholderia mallei which causes glanders, an infection primarily of horses, donkeys and mules. The name Melioidosis is derived from the Greek melis (μηλις) meaning "a distemper of asses" with the suffixes -oid meaning "similar to" and -osis meaning "a condition", that is, a condition similar to glanders.
Melioidosis is endemic in parts of southeast Asia (including Thailand, Laos and southern China, Singapore, Malaysia, Burma and Vietnam), Taiwan and northern Australia. Multiple cases have also been described in Hong Kong and Brunei India, and sporadic cases in Central and South America, the Middle East, the Pacific and several African countries.
A Papovavirus is any member of the former virus family of Papovaviridae. They are mainly associated with various neoplasms in mammals. The family of Papovaviridae is no longer used in recent taxonomy, but is split into the Papillomaviridae and the Polyomaviridae.
The name derives from three abbreviations: Pa for papillomavirus, Po for polyomavirus, and Va for "vacuolating" (simian vacuolating virus 40 or SV40, which is now known to be part of the polyomavirus genus).
Papovaviruses are DNA viruses containing double-stranded DNA, are icosahedral in shape, and do not have a lipoprotein envelope.
They are commonly found in humans and other species, mostly mammals. The one that most often causes disease in humans is the human papillomavirus.
Rubella, commonly known as German measles, is a disease caused by the rubella virus. The name "rubella" is derived from Latin, meaning little red. Rubella is also known as German measles because the disease was first described by German physicians in the mid-eighteenth century. This disease is often mild and attacks often pass unnoticed. The disease can last one to three days. Children recover more quickly than adults. Infection of the mother by Rubella virus during pregnancy can be serious; if the mother is infected within the first 20 weeks of pregnancy, the child may be born with congenital rubella syndrome (CRS), which entails a range of serious incurable illnesses. Spontaneous abortion occurs in up to 20% of cases.
Rubella is a common childhood infection usually with minimal systemic upset although transient arthropathy may occur in adults. Serious complications are very rare. Apart from the effects of transplacental infection on the developing fetus, rubella is a relatively trivial infection.
Acquired (i.e. not congenital) rubella is transmitted via airborne droplet emission from the upper respiratory tract of active cases (can be passed along by the breath of people sick
Fitz-Hugh-Curtis syndrome is a rare complication of pelvic inflammatory disease (PID) named after the two physicians, Thomas Fitz-Hugh, Jr and Arthur Hale Curtis who first reported this condition in 1934 and 1930 respectively. It involves liver capsule inflammation.
Fitz-Hugh-Curtis syndrome occurs almost exclusively in women. It is usually caused by gonorrhoea (acute gonococcal perihepatitis) or chlamydia bacteria, which cause a thinning of cervical mucus and allow bacteria from the vagina into the uterus and oviducts, causing infection and inflammation. Occasionally, this inflammation can cause scar tissue to form on Glisson's capsule, a thin layer of connective tissue surrounding the liver.
The symptoms are an acute onset, upper right-quadrant abdominal pain and tenderness aggravated by breathing, coughing or movement, and referred to the right shoulder following an episode of PID. Laparoscopy may reveal "violin string" adhesions of parietal peritoneum to liver.
Treatment involves diagnosing and treating the underlying cause correctly. The lysis of adhesions may be performed laparoscopically.
Lassa fever or Lassa hemorrhagic fever (LHF) is an acute viral hemorrhagic fever caused by the Lassa virus and first described in 1969 in the town of Lassa, in Borno State, Nigeria, in the Yedseram river valley at the south end of Lake Chad. Clinical cases of the disease had been known for over a decade but had not been connected with a viral pathogen. The infection is endemic in West African countries, and causes 300,000–500,000 cases annually, with approximately 5,000 deaths. Outbreaks of the disease have been observed in Nigeria, Liberia, Sierra Leone, Guinea, and the Central African Republic, but it is believed that human infections also exist in Democratic Republic of the Congo, Mali, and Senegal. The primary animal host of the Lassa virus is the Natal Multimammate Mouse (Mastomys natalensis), an animal indigenous to most of Sub-Saharan Africa. The virus is probably transmitted by contact with the feces or urine of animals accessing grain stores in residences.
Lassa virus is zoonotic (transmitted from animals), in that it spreads to man from rodents, specifically multi-mammate rats (Mastomys natalensis). This is probably the most common rodent in equatorial Africa, ubiquitous
Pyomyositis, also known as tropical pyomyositis or myositis tropicans, is a bacterial infection of the skeletal muscles which results in a pus-filled abscess. Pyomyositis is most common in tropical areas but can also occur in temperate zones.
Pyomyositis is most often caused by the bacterium Staphylococcus aureus. The infection can affect any skeletal muscle, but most often infects the large muscle groups such as the quadriceps or gluteal muscles.
Pyomyositis is mainly a disease of children and was first described by Scriba in 1885. Most patients are aged 2 to 5 years, but infection may occur in any age group. Infection often follows minor trauma and is more common in the tropics, where it accounts for 4% of all hospital admissions. In temperate countries such as the US, pyomyositis was a rare condition (accounting for 1 in 3000 pediatric admissions), but has become more common since the appearance of the USA300 strain of MRSA.
The abscesses within the muscle must be drained surgically (not all patient require surgery if there is no abscess). Antibiotics are given for a minimum of three weeks to clear the infection.
Campylobacteriosis is an infection by the Campylobacter bacterium, most commonly C. jejuni. It is among the most common bacterial infections of humans, often a foodborne illness. It produces an inflammatory, sometimes bloody, diarrhea or dysentery syndrome, mostly including cramps, fever and pain.
Campylobacteriosis is caused by Campylobacter bacteria (curved or spiral, motile, non–spore-forming, Gram-negative rods). The disease is usually caused by C. jejuni, a spiral and comma shaped bacterium normally found in cattle, swine, and birds, where it is nonpathogenic, but the illness can also be caused by C. coli (also found in cattle, swine, and birds), C. upsaliensis (found in cats and dogs) and C. lari (present in seabirds in particular).
One effect of campylobacteriosis is tissue injury in the gut. The sites of tissue injury include the jejunum, the ileum, and the colon. C jejuni appears to achieve this by invading and destroying epithelial cells.
C. jejuni can also cause a latent autoimmune effect on the nerves of the legs, which is usually seen several weeks after a surgical procedure of the adomen. The effect is known as an acute idiopathic demyelinating polyneuropathy (AIDP),
Ehrlichiosis ewingii infection is an infectious disease caused by an intracellular bacteria, Ehrlichia ewingii. The infection is transmitted to humans by the tick, Amblyomma americanum. This tick can also transmit Ehrlichia chaffeensis, the bacteria that causes Human monocytic ehrlichiosis (HME).
Humans contract the disease after a bite by an infected tick of the species Amblyomma americanum.
Those with an underlying immunodeficiency (such as HIV) appear to be at greater risk of contracting the disease. Compared to HME, ewingii ehrlichiosis has a decreased incidence of complications.
Like Anaplasma phagocytophilum, the causative agent of human granulocytic ehrlichiosis, Ehrlichia ewingii infects neutrophils. Infection with E. ewingii may delay neutrophil apoptosis.
Patients can present with fever, headache, myalgias, and malaise. Laboratory tests may reveal thrombocytopenia, leukopenia, and evidence of liver damage.
In endemic areas, a high index of suspicion is warranted, especially with a known exposure to ticks. The diagnosis can be confirmed by using PCR. A peripheral blood smear can also be examined for intracytoplasmic inclusions called morulae.
The treatment of choice is
Mumps (epidemic parotitis) is a viral disease of the human species, caused by the mumps virus. Before the development of vaccination and the introduction of a vaccine, it was a common childhood disease worldwide. It is still a significant threat to health in the third world, and outbreaks still occur sporadically in developed countries.
Painful swelling of the salivary glands (classically the parotid gland) is the most typical presentation. Painful testicular swelling (orchitis) and rash may also occur. The symptoms are generally not severe in children. In teenage males and men, complications such as infertility or subfertility are more common, although still rare in absolute terms. The disease is generally self-limiting, running its course before receding, with no specific treatment apart from controlling the symptoms with pain medication.
The more common symptoms of mumps are:
Other symptoms of mumps can include dry mouth, sore face and/or ears and occasionally in more serious cases, loss of voice. In addition, up to 20% of persons infected with the mumps virus do not show symptoms, so it is possible to be infected and spread the virus without knowing it.
Fever and headache are
Fournier gangrene is a type of necrotizing infection or gangrene usually affecting the perineum.
It was first described by Baurienne in 1764 and is named after a French venereologist, Jean Alfred Fournier following five cases he presented in clinical lectures in 1883.
In the majority of cases Fournier gangrene is a mixed infection caused by both aerobic and anaerobic bacteria. Death can result from Fournier gangrene.
Fournier gangrene is a urological emergency requiring intravenous antibiotics and debridement (surgical removal) of necrotic (dead) tissue. In addition to surgery and antibiotics, hyperbaric oxygen therapy (HBO) may be useful and acts to inhibit the growth of and kill the anaerobic bacteria. Despite such measures, the mortality rate overall is 40%, but 78% if sepsis is already present at the time of initial hospital admission.
The most historically prominent sufferers from this condition may have been Herod the Great, his grandson Herod Agrippa, and possibly the Roman emperor Galerius. Puerto Rican abolitionist and pro-independence leader Segundo Ruiz Belvis died from Fournier gangrene in 1868.
An estimated 750 cases have been reported in the literature, with most
Brazilian purpuric fever (BPF) is an illness of children caused by the bacterium Haemophilus influenzae biogroup aegyptius which is ultimately fatal due to sepsis. BPF was first recognized in the São Paulo state of Brazil in 1984. At this time, young children between the ages of 3 months and 10 years were contracting a strange illness which was characterized by high fever and purpuric lesions on the body. These cases were all fatal, and originally thought to be due to meningitis. It was not until the autopsies were conducted that the cause of these deaths was confirmed to be infection by H. aegyptius. Although BPF was thought to be confined to Brazil, other cases occurred in Australia and the United States during 1984–1990.
Haemophilus species are non-spore-forming gram-negative coccobacilli . They lack motility and are aerobic or facultatively anaerobic. They require preformed growth factors that are present in blood, specifically X factor(hemin) and V factor(NAD or NADP). The bacterium grows best at 35–37°C and has an optimal pH of 7.6. Haemophilus species are obligate parasites and are part of the normal flora of the human upper respiratory tract.
In documented BPF cases, the
Tinea cruris, also known as crotch itch, crotch rot, Dhobie itch, eczema marginatum, gym itch, jock itch, jock rot, and ringworm of the groin is a dermatophyte fungal infection of the groin region in any sex, though more often seen in males. In the German Sprachraum this condition is called Tinea inguinalis (from Latin inguen = groin) whereas Tinea cruris is used for a dermatophytosis of the lower leg (Latin crus).
Candidal intertrigo is an infection of the skin Candida albicans, more specifically located between intertriginous folds of adjacent skin, which can be present in the groin or scrotum, and be indistinguishable from fungal infections caused by Tinia. However, candidal infections tend to both appear and disappear with treatment more quickly.
As the common name for this condition implies, it causes itching or a burning sensation in the groin area, thigh skin folds, or anus. It may involve the inner thighs and genital areas, as well as extending back to the perineum and perianal areas.
Affected areas may appear red, tan, or brown, with flaking, rippling, peeling, or cracking skin.
The acute infection begins with an area in the groin fold about a half-inch across, usually on
Kuru is an incurable degenerative neurological disorder that is a type of transmissible spongiform encephalopathy, caused by a prion found in humans. The term "kuru" derives from the Fore word "kuria/guria" ("to shake"), a reference to the body tremors that are a classic symptom of the disease; it is also known among the Fore as the laughing sickness due to the pathologic bursts of laughter people would display when afflicted with the disease. It is now widely accepted that Kuru was transmitted among members of the Fore tribe of Papua New Guinea via cannibalism.
Kuru was first noted in the Fore tribe of the Eastern Highlands Province of Papua New Guinea as Australian administrators explored the area in 1953–1959. Kuru (Keru) was reported by W. T. Brown in Kainantu Patrol Report No 8 of 1953/54 (13 January 1954 - 20 February 1954.) .. "The first sign of impending death is a general debility which is followed by general weakness and inability to stand. The victim retires to her house. She is able to take a little nourishment but suffers from violent shivering. The next stage is that the victim lies down in the house and cannot take nourishment and death eventually ensues." The same
Chagas disease ( /ˈʃɑːɡəs/; Portuguese: doença de Chagas, [duˈẽsɐ dʒi ˈʃagɐʃ], Spanish: enfermedad de Chagas-Mazza, [ẽ̞ɱfe̞rme̞ˈð̞að̞ːe̞ ˈtʃaɣ̞az ˈmatsa], mal de Chagas in both languages; also called American trypanosomiasis) is a tropical parasitic disease caused by the flagellate protozoan Trypanosoma cruzi. T. cruzi is commonly transmitted to humans and other mammals by an insect vector, the blood-sucking "kissing bugs" of the subfamily Triatominae (family Reduviidae) most commonly species belonging to the Triatoma, Rhodnius, and Panstrongylus genera.
The disease may also be spread through blood transfusion and organ transplantation, ingestion of food contaminated with parasites, and from a mother to her fetus.
The symptoms of Chagas disease vary over the course of an infection. In the early, acute stage, symptoms are mild and usually produce no more than local swelling at the site of infection. The initial acute phase is responsive to antiparasitic treatments, with 60–90% cure rates. After 4–8 weeks, individuals with active infections enter the chronic phase of Chagas disease that is asymptomatic for 60–80% of chronically infected individuals through their lifetime.
Giardiasis — popularly known as beaver fever — is a disease caused by the flagellate protozoan Giardia lamblia (also sometimes called Giardia intestinalis and Giardia duodenalis). The giardia organism inhabits the digestive tract of a wide variety of domestic and wild animal species, as well as humans. It is a common cause of gastroenteritis in humans, infecting approximately 200 million people worldwide.
Giardiasis is passed via the fecal-oral route. Primary routes are personal contact and contaminated consumables. The more susceptible are institutional or day-care workers, travelers, those eating improperly treated food or drink, and people who have contact with individuals already infected.
It is a particular danger to people hiking or backpacking in wilderness areas worldwide, especially if they have no immediate access to medical supplies. Giardia is also suspected to be zoonotic—communicable between humans and other animals. Major reservoir hosts include beavers, dogs, cats, horses, humans, cattle and birds.
Symptoms include loss of appetite, fever, explosive diarrhea, hematuria (blood in urine), loose or watery stool, stomach cramps, upset stomach, projectile vomiting
Leprosy, also known as Hansen's disease (HD), is a chronic disease caused by the bacteria Mycobacterium leprae and Mycobacterium lepromatosis. Named after physician Gerhard Armauer Hansen, leprosy is primarily a granulomatous disease of the peripheral nerves and mucosa of the upper respiratory tract; skin lesions are the primary external sign. Left untreated, leprosy can be progressive, causing permanent damage to the skin, nerves, limbs and eyes. Contrary to folklore, leprosy does not cause body parts to fall off, although they can become numb or diseased as a result of secondary infections; these occur as a result of the body's defenses being compromised by the primary disease. Secondary infections, in turn, can result in tissue loss causing fingers and toes to become shortened and deformed, as cartilage is absorbed into the body.
Although the mode of transmission of Hansen's disease remains uncertain, most investigators think that M. leprae is usually spread from person to person in respiratory droplets. Studies have shown that leprosy can be transmitted to humans by armadillos. Leprosy is now known to be neither sexually transmitted nor highly infectious after treatment.
Peritonsillar abscess (PTA), also called a quinsy or abbreviated as PTA is a recognized complication of tonsillitis and consists of a collection of pus beside the tonsil in what is referred to as Peritonsilar space (Peri - meaning surrounding).
Unlike tonsillitis, which is more common in the pediatric age group, PTA has a more even age spread — from children to adults. Symptoms start appearing two to eight days before the formation of an abscess. Progressively worsening, unilateral sore throat and pain during swallowing usually are the earliest symptoms. As the abscess develops, persistent pain in the peritonsillar area, fever, malaise, headache and a distortion of vowels informally known as "hot potato voice" may appear. Neck pain associated with tender, swollen lymph nodes, referred ear pain and halitosis are also common. While these signs may be present in tonsillitis itself, a PTA should be specifically considered if there is limited ability to open the mouth (trismus). In Short:
Physical signs include redness and edema in the tonsillar area of the affected side and swelling of the jugulodigastric lymph nodes. The uvula may be displaced towards the unaffected side. Odynophagia
Cervical intraepithelial neoplasia (CIN), also known as cervical dysplasia and cervical interstitial neoplasia, is the potentially premalignant transformation and abnormal growth (dysplasia) of squamous cells on the surface of the cervix. CIN is not cancer, and is usually curable. Most cases of CIN remain stable, or are eliminated by the host's immune system without intervention. However a small percentage of cases progress to become cervical cancer, usually cervical squamous cell carcinoma (SCC), if left untreated. The major cause of CIN is chronic infection of the cervix with the sexually transmitted human papillomavirus (HPV), especially the high-risk HPV types 16 or 18. Over 100 types of HPV have been identified. About a dozen of these types appear to cause cervical dysplasia and may lead to the development of cervical cancer. Other types cause warts.
The earliest microscopic change corresponding to CIN is dysplasia of the epithelial or surface lining of the cervix, which is essentially undetectable by the woman. Cellular changes associated with HPV infection, such as koilocytes, are also commonly seen in CIN. CIN is usually discovered by a screening test, the Papanicolaou or
Sup35p is the Saccharomyces cerevisiae (a yeast) eukaryotic translation release factor. More specifically, it is the yeast eukaryotic release factor 3 (eRF3), which forms the translation termination complex with eRF1 (Sup45p in yeast). This complex recognizes and catalyzes the release of the nascent polypeptide chain when the ribosome encounters a stop codon. While eRF1 recognizes stop codons, eRF3 facilitates the release of the polypeptide chain through GTP hydrolysis.
Partial loss of function results in nonsense suppression, in which stop codons are ignored and proteins are abnormally synthesized with carboxyl terminal extensions. Complete loss of function is fatal.
Sup35p was shown to propagate in a prion form in 1994 by Reed Wickner. For this reason it is an intensely studied protein. When yeast cells harbor Sup35p in the prion state the resulting phenotype is known as [PSI+]. In [PSI+] cells Sup35p exists in an amyloid state that can be propagated and passed to daughter cells. This results in less soluble and functional protein and thus an in increased rate of nonsense suppression (translational read-through of stop codons).
The overexpression of the gene has been shown to
Aspergillus (/ˌæspərˈdʒɪləs/) is a genus consisting of several hundred mold species found in various climates worldwide. Aspergillus was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Micheli was reminded of the shape of an aspergillum (holy water sprinkler), from Latin spargere (to sprinkle), and named the genus accordingly. Today "aspergillum" is also the name of an asexual spore-forming structure common to all Aspergilli; around one-third of species are also known to have a sexual stage.
Aspergillus species are highly aerobic and are found in almost all oxygen-rich environments, where they commonly grow as molds on the surface of a substrate, as a result of the high oxygen tension. Commonly, fungi grow on carbon-rich substrates like monosaccharides (such as glucose) and polysaccharides (such as amylose). Aspergillus species are common contaminants of starchy foods (such as bread and potatoes), and grow in or on many plants and trees.
In addition to growth on carbon sources, many species of Aspergillus demonstrate oligotrophy where they are capable of growing in nutrient-depleted environments, or
Bacterial vaginosis (BV) or less commonly vaginal bacteriosis is a disease of the vagina caused by bacteria. According to the U.S. Centers for Disease Control and Prevention (CDC), risk factors for BV include douching and having new or multiple sex partners, although it is unclear what role sexual activity plays in the development of BV. BV is caused by an imbalance of naturally occurring bacterial flora and is often confused with yeast infection (candidiasis) or infection with Trichomonas vaginalis (trichomoniasis), which are not caused by bacteria.
BV can be asymptomatic in almost half of affected women, however the most common symptom of BV is an abnormal homogeneous off-white vaginal discharge (especially after vaginal intercourse) that may be accompanied by an unpleasant (usually fishy) smell. This malodorous discharge coats the walls of the vagina, and is usually without significant irritation, pain, or erythema (redness), although mild itching can sometimes occur. By contrast, the normal vaginal discharge will vary in consistency and amount throughout the menstrual cycle and is at its clearest at ovulation - about 2 weeks before the period starts.
A healthy vagina normally
Swine vesicular disease (SVD) is an acute, contagious viral disease of swine caused by the swine vesicular disease virus, an enterovirus. It is characterized by fever and vesicles with subsequent ulcers in the mouth and on the snout, feet, and teats. The pathogen is relatively resistant to heat, and can persist for a long time in salted, dried, and smoked meat products.
The disease can be introduced into a herd by feeding garbage containing infected meat scraps, by bringing in infected animals, or by direct contact with infected feces (such as in an improperly cleaned truck).
Clinical signs are very similar to those of foot-and-mouth disease and other vesicular diseases. They are:
There is no vaccine for SVD. Prevention measures are similar to those for foot-and-mouth disease: controlling animals imported from infected areas, and sanitary disposal of garbage from international aircraft and ships, and thorough cooking of garbage. Infected animals should be placed in strict quarantine. Eradication measures for the disease include quarantining infected areas, depopulation and disposal of infected and contact pigs, and cleaning and disinfecting contaminated premises.
Herpes zoster (or simply zoster), commonly known as shingles and also known as zona, is a viral disease characterized by a painful skin rash with blisters in a limited area on one side of the body, often in a stripe. The initial infection with varicella zoster virus (VZV) causes the acute (short-lived) illness chickenpox which generally occurs in children and young people. Once an episode of chickenpox has resolved, the virus is not eliminated from the body but can go on to cause shingles—an illness with very different symptoms—often many years after the initial infection. Herpes zoster is not the same disease as herpes simplex despite the name similarity (both the varicella zoster virus and herpes simplex virus belong to the same viral subfamily Alphaherpesvirinae).
Varicella zoster virus can become latent in the nerve cell bodies and less frequently in non-neuronal satellite cells of dorsal root, cranial nerve or autonomic ganglion, without causing any symptoms. Years or decades after a chickenpox infection, the virus may break out of nerve cell bodies and travel down nerve axons to cause viral infection of the skin in the region of the nerve. The virus may spread from one or
Phenol-soluble modulins (PSM) are a family of protein toxins that are soluble in phenols, that are produced by CA-MRSA, and which are thought to be a possible cause of severe infections.
Non-methicillin resistant bacteria were not found to produce these toxins. Although PSM toxins are produced in all methicillin-resistant Staphylococcus aureus strains, the more virulent CA-MRSA strains are typically associated with higher production. Genetic analysis demonstrated that the PSM-alpha protein, product of the psm-alpha gene cluster, was associated with enhanced virulence and enhanced destruction of white blood cells, presumably the key to the higher infectivity. However, expression of the psm-alpha genes appeared to vary, dependent upon unknown factors specific to each particular infection.
Cryptococcosis, or cryptococcal disease, is a potentially fatal fungal disease. It is caused by one of two species; Cryptococcus neoformans and Cryptococcus gattii. These were all previously thought to be subspecies of C. neoformans, but have now been identified as distinct species.
Cryptococcosis is believed to be acquired by inhalation of the infectious propagule from the environment. Although the exact nature of the infectious propagule is unknown, the leading hypothesis is the basidiospore created through sexual or asexual reproduction.
Cryptococcosis is a defining opportunistic infection for AIDS. Other conditions which pose an increased risk include certain lymphomas (e.g. Hodgkin's lymphoma), sarcoidosis, liver cirrhosis and patients on long-term corticosteroid therapy.
Distribution is worldwide in soil. The prevalence of cryptococcosis has been increasing over the past 20 years for many reasons, including the increase in incidence of AIDS and the expanded use of immunosuppressive drugs.
In humans, C. neoformans causes three types of infections:
Cryptococcal meningitis (infection of the meninges, the tissue covering the brain) is believed to result from dissemination of the
Henipavirus is a genus of the family Paramyxoviridae, order Mononegavirales containing three established species: Hendra virus, Nipah virus and Cedar Virus . The henipaviruses are naturally harboured by Pteropid fruit bats (flying foxes) and some microbat species. Henipavirus is characterised by a large genome, a wide host range, and their recent emergence as zoonotic pathogens capable of causing illness and death in domestic animals and humans.
In 2009, RNA sequences of three novel viruses in phylogenetic relationship to known Henipaviruses were detected in Eidolon helvum (the African Straw-coloured fruit bat) in Ghana. The finding of these novel putative Henipaviruses outside Australia and Asia indicates that the region of potential endemicity of Henipaviruses extends to Africa.
Henipaviruses are pleomorphic (variably shaped), ranging in size from 40 to 600 nm in diameter. They possess a lipid membrane overlying a shell of viral matrix protein. At the core is a single helical strand of genomic RNA tightly bound to N (nucleocapsid) protein and associated with the L (large) and P (phosphoprotein) proteins which provide RNA polymerase activity during replication.
Embedded within the
Contagious bovine pleuropneumonia (CBPP - also known as lung plague), is a contagious bacterial disease that afflicts the lungs of cattle, buffalo, zebu, and yaks.
It is caused by the bacterium Mycoplasma mycoides mycoides, and the symptoms are pneumonia and inflammation of the lung membranes. The incubation period is 20 to 123 days. It was particularly widespread in the United States in 1879, affecting herds from several states. The outbreak was so severe that it resulted in a trade embargo by the British government, blocking U.S. cattle exports to Britain and Canada. This prompted the United States to establish the Bureau of Animal Industry, set up in 1884 to eradicate the disease, which it succeeded in doing.
Louis Willems, a Belgium doctor, began pioneering work in the 1850s on animal inoculation against the disease.
The bacteria are widespread in Africa, the Middle East, Southern Europe, as well as parts of Asia. It is an airborne species, and can travel up to several kilometres in the right conditions.
Listeriosis is a bacterial infection caused by a Gram-positive, motile bacterium, Listeria monocytogenes. Listeriosis occurs primarily in newborn infants, elderly patients, and patients who are immunocompromised. Listeriosis kills at least 1 in 5 persons it infects. Its wide range of temperature tolerance necessitates extra care in food processing and storage. Meat and dairy products must be handled carefully to prevent contamination and growth of the pathogen. Vegetables and fruit that have contacted the soil must be carefully washed before refrigeration.
The symptoms of listeriosis usually last 7–10 days, with the most common symptoms being fever, muscle aches, and vomiting. Diarrhea is another, but less common symptom. If the infection spreads to the nervous system it can cause meningitis, an infection of the covering of the brain and spinal cord. Symptoms of meningitis are headache, stiff neck, confusion, loss of balance, and convulsions.
Listeriosis has a low incidence in humans. However, pregnant women are much more likely than the rest of the population to contract it. Infected pregnant women may have only mild, flulike symptoms. However, infection in a pregnant woman can
Creutzfeldt–Jakob disease ( /ˈkrɔɪtsfɛlt ˈjɑːkoʊb/ KROITS-felt YAH-kohb) or CJD is a degenerative neurological disorder (brain disease) that is incurable and invariably fatal. CJD is at times called a human form of mad cow disease (bovine spongiform encephalopathy or BSE) even though classic CJD is not related to BSE; however, given that BSE is believed to be the cause of variant Creutzfeldt–Jakob (vCJD) disease in humans, the two are often confused.
In CJD, the brain tissue develops holes and takes on a sponge-like texture. This is due to a type of infectious protein called a prion. Prions are misfolded proteins which replicate by converting their properly folded counterparts.
Types of CJD include:
The first symptom of CJD is rapidly progressive dementia, leading to memory loss, personality changes and hallucinations. This is accompanied by physical problems such as speech impairment, jerky movements (myoclonus), balance and coordination dysfunction (ataxia), changes in gait, rigid posture, and seizures. The duration of the disease varies greatly, but sporadic (non-inherited) CJD can be fatal within months or even weeks (Johnson, 1998). In some people, the symptoms can continue
Murray Valley encephalitis virus (MVEV) is a zoonotic flavivirus endemic to northern Australia and Papua New Guinea. It is the causal agent of Murray Valley encephalitis (previously known as Australian encephalitis) and in humans can cause permanent neurological disease or death. MVEV is related to Kunjin virus which has a similar ecology but has a lower morbidity rate. Although the arbovirus is endemic to Northern Australia, it has occasionally spread to the southern states during times of heavy rainfall during the summer monsoon season via seasonal flooding of the Murray-Darling river system. These outbreaks can be "...decades apart, with no or very few cases identified in between".
MVEV is a mosquito-borne virus that is maintained in a bird-mosquito-bird cycle. Water birds from the Ciconiiformes order, including herons and cormorants, provide the natural reservoir for MVEV. The major mosquito vector is Culex annulirostris. Human infection occurs only through bites from infected mosquitoes; the virus cannot be transmitted from person to person.
The first epidemics of MVE occurred in 1917 and 1918 in Southeastern Australia following years of high rainfall. The virus was isolated
Pyaemia (or pyemia) is a type of septicaemia that leads to widespread abscesses of a metastatic nature. It is usually caused by the staphylococcus bacteria by pus-forming organisms in the blood. Apart from the distinctive abscesses, pyaemia exhibits the same symptoms as other forms of septicaemia. It was almost universally fatal before the introduction of antibiotics.
Sir William Osler included a three-page discussion of pyaemia in his textbook The Principles and Practice of Medicine, published in 1892. He defined pyaemia as follows:
Earlier still, Ignaz Semmelweis - who would later die of the disease - included a section entitled "Childbed fever is a variety of pyaemia" in his treatise, The Etiology of Childbed Fever (1861). Jane Grey Swisshelm, in her autobiography entitled Half a Century, describes the treatment of pyaemia in 1862 during the American Civil War.
The disease is characterized by intermittent high temperature with recurrent chills; metastatic processes in various parts of the body, especially in the lungs; septic pneumonia; empyema. It may be fatal.
Antibiotics are effective. Prophylactic treatment consists in prevention of suppuration.
Brucellosis, also called Bang's disease, Crimean fever, Gibraltar fever, Malta fever, Maltese fever, Mediterranean fever, rock fever, or undulant fever, is a highly contagious zoonosis caused by ingestion of unsterilized milk or meat from infected animals or close contact with their secretions. Transmission from human to human, through sexual contact or from mother to child, is rare but possible.
Brucella spp. are small, Gram-negative, non-motile, non-spore-forming, rod shaped (coccobacilli) bacteria. They function as facultative intracellular parasites causing chronic disease, which usually persists for life. Symptoms include profuse sweating and joint and muscle pain. Brucellosis has been recognized in animals including humans since the 20th century.
Under the name Malta fever, the disease now called brucellosis first came to the attention of British medical officers in the 1850s in Malta during the Crimean War. The causal relationship between organism and disease was first established in 1887 by Dr. David Bruce.
In 1897, Danish veterinarian Bernhard Bang isolated Brucella abortus as the agent; and the additional name Bang's disease was assigned.
Maltese doctor and archaeologist
Myiasis ( /ˈmaɪ.əsɨs/ or /maɪˈaɪ.əsɨs/) is the infestation of a human being's or other vertebrate animal's body by fly larvae that feed on its tissue. When the attack is directed against dead or necrotic tissue, the condition is not necessarily harmful and the effects may be of value as maggot therapy. Colloquialisms for myiasis include flystrike, blowfly strike, and fly-blown. In Greek, "myia" means fly.
Because animals cannot react as effectively as humans to the causes and effects of myiasis, such conditions present a serious problem for livestock industries, causing severe economic losses worldwide. Although infestation by fly larvae is much more serious and more prevalent in animals, it is relatively frequent in humans in rural, tropical and subtropical regions, and often may require medical attention.
Myiasis varies widely in the forms it takes and its effects on the victims. Such variations depend largely on the fly species and where the larvae are located. Some flies lay eggs in open wounds, other larvae may invade unbroken skin or enter the body through the nose or ears, and still others may be swallowed if the eggs are deposited on the lips or on food.
Phytoreoviruses are non-turreted reoviruses that are major agricultural pathogens, particularly in Asia. One member of this family, Rice Dwarf Virus (RDV), has been extensively studied by electron cryomicroscopy and x-ray crystallography. From these analyses, atomic models of the capsid proteins and a plausible model for capsid assembly have been derived. While the structural proteins of RDV share no sequence similarity to other proteins, their folds and the overall capsid structure are similar to those of other Reoviridae.
Phytoreoviruses are unique among Reoviridae in that there are 12 dsRNA segments in each virus. Like all other Reoviridae, they contain their own RNA-dependent RNA polymerase, allowing for endogenous synthesis of viral mRNA within the virus. Although less well studied than orthoreovirus and orbivirus, considerable structural and biochemical studies have been undertaken to characterize phytoreoviruses, which in general infect plants. There are three recognized phytoreoviruses: wound tumour virus (WTV), rice dwarf virus (RDV) and rice gall dwarf virus (RGDV). Possible additional family members include tobacco leaf enation virus (TLEF), rice bunchy stunt virus and
Echinococcosis, which is often referred to as hydatid disease or echinococcal disease, is a parasitic disease that affects both humans and other mammals, such as sheep, dogs, rodents and horses. There are three different forms of echinococcosis found in humans, each of which is caused by the larval stages of different species of the tapeworm of genus Echinococcus. The first of the three and also the most common form found in humans is cystic echinococcosis (also known as unilocular echinococcosis), which is caused by Echinococcus granulosus. The second is alveolar echinococcosis (also known as alveolar colloid of the liver, alveolar hydatid disease, alveolococcosis, multilocular echinococcosis, “small fox tapeworm”), which is caused by Echinococcus multilocularis and the third is polycystic echinococcosis (also known as human polycystic hydatid disease, neotropical echinococcosis), which is caused by Echinococcus vogeli and very rarely, Echinococcus oligarthus. Alveolar and polycystic echinococcosis are rarely diagnosed in humans and are not as widespread as cystic echinococcosis, but polycystic echinococcosis is relatively new on the medical scene and is often left out of
Hymenolepiasis is infestation by one of two species of tapeworm:
Alternative names are:
Hymenolepis worms live in the intestines of rats and are common in warm climates. Hymenolepis is generally found in the feces of rats which is consumed by its secondary hosts: beetles. The worms mature into a life form referred to as a "cysticercoid" in the insect; in H. nana, the insect is always a beetle. Humans and other animals become infected when they intentionally or unintentionally eat material contaminated by insects. In an infected person, it is possible for the worm's entire life-cycle to be completed in the bowel, so infection can persist for years if left untreated. Hymenolepis nana infections are much more common than Hymenolepis diminuta infections in humans because, in addition to being spread by insects, the disease can be spread directly from person to person by eggs in feces. When this happens, H. nana oncosphere larvae encyst in the intestinal wall and develop into cysticercoids and then adults. These infections were previously common in the southeastern USA, and have been described in crowded environments and individuals confined to institutions. However, the disease occurs
Poliomyelitis (pōlee-ō-mī-ə-lītiss), often called polio or infantile paralysis, is an acute, viral, infectious disease spread from person to person, primarily via the fecal-oral route. The term derives from the Greek poliós (πολιός), meaning "grey", myelós (µυελός “marrow”), referring to the grey matter of the spinal cord, and the suffix -itis, which denotes inflammation., i.e., inflammation of the spinal cord’s grey matter, although a severe infection can extend into the brainstem and even higher structures, resulting in polioencephalitis, producing apnea that requires mechanical assistance such as an iron lung.
Although approximately 90% of polio infections cause no symptoms at all, affected individuals can exhibit a range of symptoms if the virus enters the blood stream. In about 1% of cases, the virus enters the central nervous system, preferentially infecting and destroying motor neurons, leading to muscle weakness and acute flaccid paralysis. Different types of paralysis may occur, depending on the nerves involved. Spinal polio is the most common form, characterized by asymmetric paralysis that most often involves the legs. Bulbar polio leads to weakness of muscles innervated
Syphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The primary route of transmission is through sexual contact; it may also be transmitted from mother to fetus during pregnancy or at birth, resulting in congenital syphilis. Other human diseases caused by related Treponema pallidum include yaws (subspecies pertenue), pinta (subspecies carateum), and bejel (subspecies endemicum).
The signs and symptoms of syphilis vary depending in which of the four stages it presents (primary, secondary, latent, and tertiary). The primary stage classically presents with a single chancre (a firm, painless, non-itchy skin ulceration), secondary syphilis with a diffuse rash which frequently involves the palms of the hands and soles of the feet, latent syphilis with little to no symptoms, and tertiary syphilis with gummas, neurological, or cardiac symptoms. It has, however, been known as "the great imitator" due to its frequent atypical presentations. Diagnosis is usually via blood tests; however, the bacteria can also be visualized under a microscope. Syphilis can be effectively treated with antibiotics, specifically the preferred
Bornholm disease or epidemic pleurodynia or epidemic myalgia is a disease caused by the Coxsackie B virus or other viruses.
It is named after the Danish island Bornholm where early cases occurred.
Symptoms may include fever and headache, but the distinguishing characteristic of this disease is attacks of severe pain in the lower chest, often on one side. The slightest movement of the rib cage causes a sharp increase of pain, which makes it very difficult to breathe, and an attack is therefore quite a frightening experience, although it generally passes off before any actual harm occurs. The attacks are unpredictable and strike "out of the blue" with a feeling like an iron grip around the rib cage. The colloquial names for the disease, such as 'The Devil's grip' (see also "other names" below) reflect this symptom.
Inoculation of throat washings taken from people with pleurodynia into the brains of newborn mice revealed that enteroviruses in the Coxsackie B virus group were likely to be the cause of pleurodynia, and those findings were supported by subsequent studies of IgM antibody responses measured in serum from people with pleurodynia. Other viruses in the enterovirus family,
A Brodie abscess is a subacute osteomyelitis, which may persist for years before converting to a frank osteomyelitis. Classically, this may present after conversion as a draining abscess extending from the tibia out through the shin.
Most frequent causative organism is Staphylococcus aureus.
Localized pain, often nocturnal, alleviated by aspirin. Often mimics the symptoms of Osteoid osteoma, which is typically 1 cm surrounded by a heavily reactive sclerosis, granulation tissue, and a nidus often less than 1 cm. The margins often appear scalloped on radiograph. Brodie's abscess is best visualized using Computed tomography (CT) scan. Associated atrophy of soft tissue near the site of infection and shortening of the affected bone. Osteoblastoma may be a classic sign for Brodie's abscess.
Brodie abscess is named after Sir Benjamin Collins Brodie, 1st Baronet
Mainly surgical approach has to be taken. If cavity is small then surgical evacuation & curettage is performed under
Genital warts (or Condylomata acuminata, venereal warts, anal warts and anogenital warts) is a highly contagious sexually transmitted disease caused by some sub-types of human papillomavirus (HPV). It is spread through direct skin-to-skin contact during oral, genital, or anal sex with an infected partner. Warts are the most easily recognized symptom of genital HPV infection, where types 6 and 11 are responsible for 90% of genital warts cases.
Although it is estimated that only a "small percentage" (between 1% and 5%) of those infected with genital HPV develop genital warts, those infected can still transmit the virus. Other types of HPV also cause cervical cancer and probably most anal cancers, however it is important to underline that the types of HPV that cause the overwhelming majority of genital warts are not the same as those that can potentially increase the risk of genital or anal cancer. HPV prevalence at any one time has been observed in some studies at 27% over all sexually active people, rising to 45% between the ages of 14 and 19.
Genital warts often occur in clusters and can be very tiny or can spread into large masses in the genital or penis area. In other cases they
Rickettsia rickettsii (abbreviated as R. rickettsii) is a unicellular, gram-negative coccobacillus (plural coccobacilli) that is native to the New World. It belongs to the spotted fever group (SFG) of Rickettsia and is most commonly known as the causative agent of Rocky Mountain spotted fever (RMSF). By nature, R. rickettsii is an obligate intracellular parasite that survive by an endosymbiotic relationship with other cells.
R. rickettsii is a non-motile, non-spore forming aerobic organism. Cells are typically 0.3-0.5 X 0.8-2.0 um in size. They lack a distinct nucleus and membrane bound organelles. Their outer membrane is composed mostly lipopolysaccharides.
RMSF is transmitted by the bite of an infected tick while feeding on warm-blooded animals, including humans. Humans are considered to be accidental hosts in the Rickettsia–tick life cycle and are not required to maintain the rickettsiae in nature.
Rocky Mountain spotted fever first emerged in the Idaho Valley in 1896. At that time, not much information was known about the disease; it was originally called Black Measles because patients had a characteristic spotted rash appearance throughout their body.
Athlete's foot (also known as ringworm of the foot and tinea pedis) is a fungal infection of the skin that causes scaling, flaking, and itch of affected areas. It is caused by fungi in the genus Trichophyton and is typically transmitted in moist areas where people walk barefoot, such as showers or bathhouses, however in order to incubate it requires the foot to remain moist and so is only seen in approximately 0.75% of habitually (always) barefoot people. Although the condition typically affects the feet, it can infect or spread to other areas of the body, including the groin, particularly areas of skin that are kept hot and moist, such as with insulation, body heat, and sweat in a shoe, for long periods of time. While the fungus is generally picked up through walking barefoot in an infected area or using an infected towel, infection can be prevented by remaining barefoot as this allows the feet to dry properly and removes the fungus' primary incubator - the warm moist interior of a shoe. Athlete's foot can be treated by a number of pharmaceuticals (including creams) and other treatments.
Athlete's foot causes scaling, flaking, and itching of the affected skin. Blisters and cracked
Botryomycosis; also known as bacterial pseudomycosis is a rare chronic granulomatous bacterial infection that affects the skin, and sometimes the viscera.
Botryomycosis has been known to affect humans, horses, cattle, swine, dogs and cats. It can occur in recently castrated horses if proper hygiene isn't followed and the end of the spermatic chord becomes infected with S. aureus.
The disease was originally discovered by Otto Bollinger (1843–1909) in 1870, and its name was coined by Sebastiano Rivolta (1832–1893) in 1884. The name refers to its grape-like granules (Gr. botryo = grapes) and the mistakenly implied fungal etiology (Gr. mykes = fungus). In 1919 the bacterial origin of the infection was discovered.
Staphylococcus aureus is usually the organism that causes the infection, however it can also be caused by Pseudomonas aeruginosa or several other species of bacteria. The anatomic structure of its lesion is similar to that of actinomycosis and mycetoma, and its granules resemble the sulfur granules of actinomycosis.
There are only a handful of documented cases of botryomycosis in humans, and its pathogenesis is not completely understood. However, it is usually described in
Bronchiolitis is inflammation of the bronchioles, the smallest air passages of the lungs. It usually occurs in children less than two years of age and presents with coughing, wheezing, and shortness of breath. This inflammation is usually caused by respiratory syncytial virus. Treatment is typically supportive and may involve the use of nebulized epinephrine or hypertonic saline.
In a typical case, an infant under two years of age develops cough, wheeze, and shortness of breath over one or two days. The infant may be breathless for several days. After the acute illness, it is common for the airways to remain sensitive for several weeks, leading to recurrent cough and wheeze.
The term usually refers to acute viral bronchiolitis, a common disease in infancy. This is most commonly caused by respiratory syncytial virus (RSV, also known as human pneumovirus). Other viruses which may cause this illness include metapneumovirus, influenza, parainfluenza, coronavirus, adenovirus, and rhinovirus.
Studies have shown there is a link between voluntary caesarean birth and an increased prevalence of bronchiolitis. A recent study by Perth's Telethon Institute for Child Health Research has shown an
Cholera is an infection in the small intestine caused by the bacterium Vibrio cholerae. The main symptoms are profuse, watery diarrhea and vomiting. Transmission occurs primarily by drinking water or eating food that has been contaminated by the feces of an infected person, including one with no apparent symptoms. The severity of the diarrhea and vomiting can lead to rapid dehydration and electrolyte imbalance, and death in some cases. The primary treatment is oral rehydration therapy, typically with oral rehydration solution (ORS), to replace water and electrolytes. If this is not tolerated or does not provide improvement fast enough, intravenous fluids can also be used. Antibacterial drugs are beneficial in those with severe disease to shorten its duration and severity. Worldwide, it affects 3–5 million people and causes 100,000–130,000 deaths a year as of 2010. Cholera was one of the earliest infections to be studied by epidemiological methods.
The primary symptoms of cholera are profuse, painless diarrhea and vomiting of clear fluid. These symptoms usually start suddenly, one to five days after ingestion of the bacteria. The diarrhea is frequently described as "rice water" in
An intertrigo is an inflammation (rash) of the body folds (adjacent areas of skin).
An intertrigo sometimes refers to a bacterial, fungal, or viral infection that has developed at the site of broken skin due to such inflammation. A frequent manifestation is Candidal intertrigo.
An intertrigo usually develops from the chafing of warm, moist skin in the areas of the inner thighs and genitalia, the armpits, under the breasts, the underside of the belly, behind the ears, and the web spaces between the toes and fingers. An intertrigo usually appears red and raw-looking, and may also itch, ooze, and be sore. Intertrigos occur more often among overweight individuals, those with diabetes, those restricted to bed rest or diaper use, and those who use medical devices, like artificial limbs, that trap moisture against the skin. Also, there are several skin diseases that can cause an intertrigo to develop, such as dermatitis or inverse psoriasis.
In general, treatment for all skin rashes, less is more, and consult a dermatologist if it persists for more than a week. Infections can be treated with a topical and/or oral medication(s). The most common treatment being a baby diaper rash ointment
Molluscum contagiosum (MC) is a viral infection of the skin or occasionally of the mucous membranes, sometimes called water warts. It is caused by a DNA poxvirus called the molluscum contagiosum virus (MCV). MCV has no animal reservoir, infecting only humans. There are four types of MCV, MCV-1 to -4; MCV-1 is the most prevalent and MCV-2 is seen usually in adults and often sexually transmitted. This common viral disease has a higher incidence in children, sexually active adults, and those who are immunodeficient, and the infection is most common in children aged one to ten years old. MC can affect any area of the skin but is most common on the trunk of the body, arms, and legs. It is spread through direct contact or shared items such as clothing or towels.
The virus commonly spreads through skin-to-skin contact. This includes sexual contact or touching or scratching the bumps and then touching the skin. Handling objects that have the virus on them (fomites), such as a towel, can also result in infection. The virus can spread from one part of the body to another or to other people. The virus can be spread among children at day care or at school. Molluscum contagiosum is contagious
Pharyngoconjunctival fever is caused by adenovirus infection.
Age group 5-18
Often found in summer camps and during the spring and fall in schools. In Japan, the illness is commonly referred to as "pool fever" as it is often spread via public swimming pools.
Clonorchiasis is an infectious disease caused by the Chinese liver fluke, Clonorchis sinensis. Clonorchiasis is a known risk factor for the development of cholangiocarcinoma, a neoplasm of the biliary system.
Symptoms of opisthorchiasis caused by Opisthorchis viverrini and by Opisthorchis felineus are indistinguishable from clonorchiasis caused by Clonorchis sinensis, so the disease by these three parasites should be referred as clonorchiasis.
Clonorchiasis sinensis is a trematode (fluke) which is part of the phylum Platyhelminthes. It is a hermaphroditic fluke that requires two intermediate hosts. The parasitic worm is as long as 10 to 25mm and lives in the bile ducts of the liver. The eggs of the worms are passed through fecal matter which are then ingested by mollusks. One becomes infected by eating undercooked, smoked, pickled or salted freshwater fish. Freshwater fish are a second intermediate host for the parasitic worm. They become infected when the larvae (cercaria) of the worm penetrates the flesh of the fish. The water snail is the first intermediate host in which a miracidium (an embryonated egg discharged in stool) goes through its developmental stages of (sporocyst,
Pediculosis capitis (also known as head lice infestation, "nits" and cooties) is a human medical condition caused by the colonization of the hair and skin by the parasitic insect Pediculus humanus capitis—the head louse. Typically, only the head or scalp of the host is infested. Head lice feed on human blood (hematophagy), and itching from lice bites is a common symptom of this condition. Treatment typically includes application of topical insecticides such as a pyrethrin or permethrin, although a variety of herbal remedies are also common.
Lice infestation in general is known as pediculosis, and occurs in many mammalian and bird species. The term pediculosis capitis, or simply "pediculosis", is sometimes used to refer to the specific human pediculosis due to P. humanus capitis (i.e., head-louse infestation). Humans are hosts for two other lice as well — the body louse and the crab louse.
Head-lice infestation is widely endemic, especially in children. It is a cause of some concern in public health, although, unlike human body lice, head lice are not carriers of other infectious diseases. It has been suggested that in the past, head lice infection has been a mutualistic beneficial
Impetigo /ɪmpɨˈtaɪɡoʊ/ is a highly contagious bacterial skin infection most common among pre-school children. People who play close contact sports such as rugby, American football and wrestling are also susceptible, regardless of age. Impetigo is not as common in adults. The name derives from the Latin impetere ("assail"). It is also known as school sores.
This common form of impetigo, also called nonbullous impetigo, most often begins as a red sore near the nose or mouth which soon breaks, leaking pus or fluid, and forms a honey-colored scab followed by a red mark which heals without leaving a scar. Sores are not painful but may be itchy. Lymph nodes in the affected area may be swollen, but fever is rare. Touching or scratching the sores may easily spread the infection to other parts of the body.
Bullous impetigo, mainly seen in children younger than 2 years, involves painless, fluid-filled blisters, mostly on the arms, legs and trunk, surrounded by red and itchy (but not sore) skin. After breaking, the blisters, which may be large or small, form yellow scabs.
In this form of impetigo, painful fluid- or pus-filled sores, usually on the arms and legs, become ulcers penetrating
Marburg virus (pronunciation: /ˈmɑrbərɡ ˈvaɪrəs/ MAR-bərg VY-rəs) was first noticed and described during small epidemics in the German cities Marburg and Frankfurt and the Yugoslavian capital Belgrade in the 1960s. Workers were accidentally exposed to tissues of infected grivets (Chlorocebus aethiops) at the city's former main industrial plant, the Behringwerke, then part of Hoechst, and today of CSL Behring. During these outbreaks, 31 people became infected and seven of them died. Marburg virus (MARV) causes severe disease in humans and nonhuman primates in the form of viral hemorrhagic fever. MARV is a Select Agent, WHO Risk Group 4 Pathogen (requiring biosafety level 4-equivalent containment), NIH/National Institute of Allergy and Infectious Diseases Category A Priority Pathogen, Centers for Disease Control and Prevention Category A Bioterrorism Agent, and is listed as a biological agent for export control by the Australia Group.
Marburg virus was first described in 1967. Today, the virus is one of two members of the species Marburg marburgvirus, which is included into the genus Marburgvirus, family Filoviridae, order Mononegavirales. The name Marburg virus is derived from
Salmonellosis is an infection with Salmonella bacteria. Most people infected with Salmonella develop diarrhea, fever, vomiting, and abdominal cramps 12 to 72 hours after infection. In most cases, the illness lasts four to seven days, and most people recover without treatment. However, in some cases the diarrhea may be so severe that the patient becomes dangerously dehydrated and must be taken to a hospital.
At the hospital, the patient may receive intravenous fluids to treat the dehydration, and may be given medications to provide symptomatic relief, such as fever reduction. In severe cases, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites, and can cause death unless the person is treated promptly with antibiotics.
The elderly, infants, and those with impaired immune systems are more likely to develop severe illness. Some people afflicted with salmonellosis later experience reactive arthritis, which can have long-lasting, disabling effects. The different kinds of Salmonella include S. bongori and S. enterica.
The type of Salmonella usually associated with infections in humans, nontyphoidal Salmonella, is usually contracted
Turkeypox is a virus of the family Poxviridae and the genus Avipoxvirus. It is one of the most common diseases in the Wild Turkey (Meleagris gallopavo) population.
Turkeypox is caused by the fowlpox virus, which infects birds.
Turkeypox, like all avipoxviruses, is transmitted either through skin contact or by arthropods (typically mosquitos) acting as mechanical vectors.
Ure2p is a yeast protein that represses transcription of genes involved in nitrogen catabolism. It specifically regulates the utilization of poor nitrogen sources in the presence of preferred nutrients such as ammonia or glutamine. Ure2p is one of the few yeast proteins that are known to be prions. At low frequency the protein adopts an alternative conformation that is auto-catalytic and self-propagating. Yeast cells that carry the protein in the prion conformation are designated as [URE3]. Autocatalytic conversion of Ure2p into the inactive prion form of the protein results in a loss of repression of nitrogen catabolic genes.
Protease-sensitive prionopathy (PSPr) is a neurodegenerative disorder caused by an abnormal isoform of the prion protein. Contrary to the prions in Creutzfeldt-Jakob disease (CJD), the prions in this condition are sensitive to protease activity.
PSPr was first described in an abstract for a conference on prions in 2006, and this study was published in a 2008 report on 11 cases. The study was conducted by Gambetti P. and coworkers from the United States National Prion Disease Pathology Surveillance Center.
Symptoms of PSPr are behavioral and psychiatric abnormalities with progressive decline in cognitive and motor functions (including dementia, ataxia, parkinsonism, psychosis, aphasia and mood disorders). This is similar to what occurs in other spongiform encephalopathies, and the condition can be mistaken for Alzheimer's dementia.
Contrary to what is the case in CJD, there were no cases with a positive 14-3-3 protein test in the cerebrospinal fluid, no periodic complexes on electroencephalography (EEG), and no pathognomonic changes on diffusion-weighted magnetic resonance images. The mean age of onset in the original 11 patients was 62 years. Patients progressed to death in 20
Scrub typhus or Bush typhus is a form of typhus caused by the intracellular parasite Orientia tsutsugamushi, a gram-negative α-proteobacterium of family Rickettsiaceae first isolated and identified in 1930 in Japan.
Although the disease is similar in presentation to other forms of typhus, its pathogen is not anymore included in genus Rickettsia with the typhus bacteria proper, but in Orientia. The disease is thus frequently classified separately from the other typhi.
Scrub typhus is transmitted by some species of trombiculid mites ("chiggers", particularly Leptotrombidium deliense), which are found in areas of heavy scrub vegetation. The bite of this mite leaves a characteristic black eschar that is useful to the doctor for making the diagnosis.
Scrub typhus is endemic to a part of the world known as the tsutsugamushi triangle (after O. tsutsugamushi). This extends from northern Japan and far-eastern Russia in the north, to the territories around the Solomon Sea into northern Australia in the south, and to Pakistan and Afghanistan in the west.
The precise incidence of the disease is unknown, as diagnostic facilities are not available in much of its large native range which spans
Toxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii. The parasite will infect most genera of warm-blooded animals, including humans, but the primary host is the felid (cat) family. The parasite spreads by the ingestion of infected meat or the feces of an infected cat, or by vertical transmission from mother to fetus. A 2001 study found that direct contact with pet cats is probably a less common route of transmission to human hosts than contamination of hands with cat feces by touching the earth, and that "contact with infected raw meat is probably a more important cause of human infection in many countries". This disease has also been directly correlated to festering human fluids, such as feces, vomit, or urine. These liquids can provide a breeding ground for toxoplasmotic parasites in a matter of hours in warm, dark environments. Toxoplasmosis kills thousands of impoverished and homeless people yearly who are living in squalid environments in which they might encounter festering human fluids.
From one-third to half of the world's human population is estimated to carry a Toxoplasma infection. The Centers for Disease Control and Prevention notes that
Cowpox is a skin disease caused by a virus known as the Cowpox virus. The pox is related to the vaccinia virus and got its name from the distribution of the disease when dairymaids touched the udders of infected cows. The ailment manifests itself in the form of red blisters and is transmitted by touch from infected animals to humans. Cowpox is similar to but much milder than the highly contagious and sometimes deadly smallpox disease. It resembles mild smallpox, and was the basis of the first smallpox vaccines. When the patient recovers from cowpox, the person is immune to smallpox.
The cowpox virus was used to perform the first successful vaccination against a disease, smallpox, which is caused by the related Variola virus. Therefore, the word "vaccination" — first used by Edward Jenner (an English physician) in 1796 — has the Latin root vaccinus meaning of or from cows. World Health Organization in 1980 announced that smallpox was the first disease that had been eradicated world wide by a program of vaccination. Despite the eradication of smallpox in the past century, other orthopoxviruses, such as monkeypox virus, vaccinia virus in Brazil, and cowpox virus (CPXV) in Europe,
Gonorrhea (colloquially known as the clap) is a common human sexually transmitted infection caused by the bacterium Neisseria gonorrhoeae. The usual symptoms in men are burning with urination and penile discharge. Women, on the other hand, are asymptomatic half the time or have vaginal discharge and pelvic pain. In both men and women if gonorrhea is left untreated, it may spread locally causing epididymitis or pelvic inflammatory disease or throughout the body, affecting joints and heart valves.
Treatment is commonly with ceftriaxone as antibiotic resistance has developed to many previously used medications. This is typically given in combination with either azithromycin or doxycycline, because Gonorrhea infections typically occur along with Chlamydia, ceftriaxone does not cover Chlamydia so these medications are needed to cover, Chlamydia, and these medications do not cover Gonorrhea. There have been some strains of gonorrhea showing resistance to ceftriaxone.
Half of women with gonorrhea are asymptomatic while others have vaginal discharge, lower abdominal pain or pain with intercourse. Most men who are infected have symptoms such as urethritis associated with burning with
Malaria is a mosquito-borne infectious disease of humans and other animals caused by protists (a type of microorganism) of the genus Plasmodium. It begins with a bite from an infected female mosquito, which introduces the protists via its saliva into the circulatory system, and ultimately to the liver where they mature and reproduce. The disease causes symptoms that typically include fever and headache, which in severe cases can progress to coma or death. Malaria is widespread in tropical and subtropical regions in a broad band around the equator, including much of Sub-Saharan Africa, Asia, and the Americas.
Five species of Plasmodium can infect and be transmitted by humans. The vast majority of deaths are caused by P. falciparum while P. vivax, P. ovale, and P. malariae cause a generally milder form of malaria that is rarely fatal. The zoonotic species P. knowlesi, prevalent in Southeast Asia, causes malaria in macaques but can also cause severe infections in humans. Malaria is prevalent in tropical regions because the significant amounts of rainfall, consistently high temperatures and high humidity, along with stagnant waters in which mosquito larvae readily mature, provide them
Psittacine beak and feather disease is a viral disease affecting all Old World and New World Parrots (Psittacini, Hookbills). The virus belongs to the family Circoviridae. The virus attacks the feather follicles and the beak and claws-growing cells of the bird, causing progressive feather malformation and necrosis. In later stages of the disease, the feathers develop constrictions in feather shafts, cease development early until eventually all feather growth stops.
The beak and claws are affected in opposite direction – overgrowth, malformation and necrotic tissue development. Cracking and peeling of outer layers makes it possible for fungi and yeast infections to take place and complicate matters even more. The necrosis of inner layers of the beak may cause it to break, at which point the bird will be unable to feed.
The disease also has a general immunosuppressive effect on the bird, clearing path for secondary systemic viral and bacterial infections which are usually the cause of death, not the PBFD virus itself. Previously unpublished data from Dr Ross Perry indicates that aspects of the immune system are working over-time, perhaps similar to an auto-immune disease in chronic
Rabies (pronounced /ˈreɪbiːz/. From Latin: rabies, "madness") is a viral disease that causes acute encephalitis (inflammation of the brain) in warm-blooded animals. The disease is zoonotic, meaning it can be transmitted from one species to another, such as from dogs to humans, commonly by a bite from an infected animal. For a human, rabies is almost invariably fatal if postexposure prophylaxis is not administered prior to the onset of severe symptoms. The rabies virus infects the central nervous system, ultimately causing disease in the brain and death.
The rabies virus travels to the brain by following the peripheral nerves. The incubation period of the disease is usually a few months in humans, depending on the distance the virus must travel to reach the central nervous system. Once the rabies virus reaches the central nervous system and symptoms begin to show, the infection is virtually untreatable and usually fatal within days.
Early-stage symptoms of rabies are malaise, headache and fever, progressing to acute pain, violent movements, uncontrolled excitement, depression, and hydrophobia. Finally, the patient may experience periods of mania and lethargy, eventually leading to
Actinomycosis is an infectious bacterial disease caused by Actinomyces species such as Actinomyces israelii or A. gerencseriae. It can also be caused by Propionibacterium propionicus, and the condition is likely to be polymicrobial aerobic anaerobic infection.
Actinomycosis occurs rarely in humans but rather frequently in cattle as a disease called lumpy jaw. This name refers to the large abscesses that grow on the head and neck of the infected animal. It can also affect swine, horses, and dogs, and less often wild animals and sheep.
The disease is characterized by the formation of painful abscesses in the mouth, lungs, or gastrointestinal tract. Actinomycosis abscesses grow larger as the disease progresses, often over months. In severe cases, they may penetrate the surrounding bone and muscle to the skin, where they break open and leak large amounts of pus. The purulent leakage via the sinus cavities contains "sulfur granules," not actually sulfur-containing but resembling such particles. These granules contain progeny bacteria.
Actinomycosis is primarily caused by any of several members of the bacterial genus Actinomyces. These bacteria are generally anaerobes. In animals, they
Hepatitis C is an infectious disease affecting primarily the liver, caused by the hepatitis C virus (HCV). The infection is often asymptomatic, but chronic infection can lead to scarring of the liver and ultimately to cirrhosis, which is generally apparent after many years. In some cases, those with cirrhosis will go on to develop liver failure, liver cancer or life-threatening esophageal and gastric varices.
HCV is spread primarily by blood-to-blood contact associated with intravenous drug use, poorly sterilized medical equipment and transfusions. An estimated 130–170 million people worldwide are infected with hepatitis C. The existence of hepatitis C (originally "non-A non-B hepatitis") was postulated in the 1970s and proven in 1989. Hepatitis C only infects humans and chimpanzees.
The virus persists in the liver in about 85% of those infected. This persistent infection can be treated with medication: the standard therapy is a combination of peginterferon and ribavirin, with either boceprevir or telaprevir added in some cases. Overall, 50–80% of people treated are cured. Those who develop cirrhosis or liver cancer may require a liver transplant. Hepatitis C is the leading cause
Isosporiasis is a human intestinal disease caused by the parasite Isospora belli. It is found worldwide, especially in tropical and subtropical areas. Infection often occurs in immuno-compromised individuals, notably AIDS patients, and outbreaks have been reported in institutionalized groups in the United States. The first documented case was in 1915.
The coccidian parasite Isospora belli infects the epithelial cells of the small intestine, and is the least common of the three intestinal coccidia that infect humans (Toxoplasma, Cryptosporidium, and Isospora).
At time of excretion, the immature oocyst contains usually one sporoblast (more rarely two). In further maturation after excretion, the sporoblast divides in two, so the oocyst now contains two sporoblasts. The sporoblasts secrete a cyst wall, thus becoming sporocysts; and the sporocysts divide twice to produce four sporozoites each. Infection occurs by ingestion of sporocyst-containing oocysts: the sporocysts excyst in the small intestine and release their sporozoites, which invade the epithelial cells and initiate schizogony. Upon rupture of the schizonts, the merozoites are released, invade new epithelial cells, and
Kaposi's sarcoma (KS) is a tumor caused by Human herpesvirus 8 (HHV8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV). It was originally described by Moritz Kaposi (KA-po-she), a Hungarian dermatologist practicing at the University of Vienna in 1872. It became more widely known as one of the AIDS defining illnesses in the 1980s. The viral cause for this cancer was discovered in 1994. Although KS is now well-established to be caused by a viral infection, there is widespread lack of awareness of this even among persons at risk for KSHV/HHV-8 infection.
Kaposi’s sarcoma (KS) is a systemic disease that can present with cutaneous lesions with or without internal involvement. Four subtypes have been described: Classic KS, affecting middle aged men of Mediterranean and Jewish descent; African endemic KS; KS in iatrogenically immunosuppressed patients; and AIDS-related KS. The erythematous to violaceous cutaneous lesions seen in KS have several morphologies: macular, patch, plaque, nodular, and exophytic. The cutaneous lesions can be solitary, localized or disseminated. KS can involve the oral cavity, lymph nodes, and viscera. Classic KS tends to be indolent, presenting with
Monkeypox is an exotic infectious disease caused by the monkeypox virus. The disease was first identified in laboratory monkeys, hence its name, but in its natural state it seems to infect rodents more often than primates. The disease is most prevalent in Central and West Africa, but an outbreak also occurred in the United States in 2003.
Human monkeypox is a zoonotic viral disease that occurs primarily in remote villages of Central and West Africa in proximity to tropical rainforests where there is more frequent contact with infected animals. Monkeypox is usually transmitted to humans from rodents, pets, and primates through contact with the animal's blood or through a bite. Human monkeypox can be difficult to distinguish clinically from smallpox (to which it is closely related) and chickenpox (to which it is not).
In addition to monkeys, giant pouched rats (Cricetomys sp.), dormice (Graphiurus sp.) and African squirrels (Heliosciurus, Funisciurus) have all been implicated as reservoirs of the virus. The use of these animals as food may be an important source of transmission to humans.
Monkeypox as a disease in humans was first associated with an illness in the Democratic Republic
Necrotizing fasciitis (/ˈnɛkrəˌtaɪzɪŋ ˌfæʃiˈaɪtɪs/ or /ˌfæs-/) or NF, commonly known as flesh-eating disease or flesh-eating bacteria syndrome, is a rare infection of the deeper layers of skin and subcutaneous tissues, easily spreading across the fascial plane within the subcutaneous tissue.
Necrotizing fasciitis is quickly progressing, having greater risk of developing in the immunocompromised due to conditions like Diabetes, Cancer, etc. It is a severe disease of sudden onset and is usually treated immediately with high doses of intravenous antibiotics.
Type I describes a polymicrobial infection, whereas Type II describes a monomicrobial infection. Many types of bacteria can cause necrotizing fasciitis (e.g., Group A streptococcus (Streptococcus pyogenes), Staphylococcus aureus, Clostridium perfringens, Bacteroides fragilis, Aeromonas hydrophila). Such infections are more likely to occur in people with compromised immune systems.
Historically, Group A streptococcus made up most cases of Type II infections. However, since as early as 2001, another serious form of monomicrobial necrotizing fasciitis has been observed with increasing frequency, caused by methicillin-resistant
Rickettsialpox is an illness caused by bacteria of the Rickettsia genus (Rickettsia akari). Physician Robert Huebner and self-trained entomologist Charles Pomerantz played major roles in identifying the etiology of the disease after an outbreak in 1946 in a New York City apartment complex, documented in medical writer Berton Roueché's short story, "The Alerting of Mr. Pomerantz."
Although it is not transmitted by a tick (a characteristic of spotted fever), the bacteria is a part of the spotted fever group of Rickettsia, and so this condition is often classified with that group.
The initial outbreak of the disease took place in the Regency Park complex which had 69 apartment units organized in three groups each three stories in height, located in Kew Gardens, in the New York City borough of Queens. Physicians who had seen patients starting in early 1946 had assumed that they were dealing with an atypical form of chickenpox, but the realization was made that they were dealing with a localized epidemic of unknown origins starting in the summer of that year. Physicians canvassed the residents of the building and found that there had been 124 cases of this disease from January through
Chronic bacterial prostatitis is a bacterial infection of the prostate gland. It should be distinguished from other forms of prostatitis such as acute bacterial prostatitis and chronic pelvic pain syndrome (CPPS).
Chronic bacterial prostatitis is a relatively rare condition that usually presents with an intermittent UTI-type picture. It is defined as recurrent urinary tract infections in men originating from a chronic infection in the prostate. Symptoms may be completely absent until there is also bladder infection, and the most troublesome problem is usually recurrent cystitis. Chronic bacterial prostatitis occurs in less than 5% of patients with prostate-related non-BPH lower urinary tract symptoms (LUTS). Dr. Weidner, Professor of Medicine, Department of Urology, University of Gießen, has stated: "In studies of 656 men, we seldom found chronic bacterial prostatitis. It is truly a rare disease. Most of those were E-coli."
In chronic bacterial prostatitis there are bacteria in the prostate, but there may be no symptoms or milder symptoms than occur with acute prostatitis. The prostate infection is diagnosed by culturing urine as well as prostate fluid (expressed prostatic
Meningococcal septicaemia (or meningococcal septicemia), or meningococcaemia, is a form of sepsis, the causative organism being Neisseria meningitidis.
It is caused by the release of toxins into the blood that break down the walls of blood vessels. A rash can develop under the skin due to blood leakage that may leave red or brownish pin prick spots.
The effective vaccine against this is meningococcal vaccine.
Strongyloidiasis is a human parasitic disease caused by the nematode (roundworm) Strongyloides stercoralis, or sometimes S. fülleborni. It can cause a number of symptoms in people, principally skin symptoms, abdominal pain, diarrhea and weight loss. In some people, particularly those who require corticosteroids or other immunosuppressive medication, Strongyloides can cause a hyperinfection syndrome that can lead to death if untreated. The diagnosis is made by blood and stool tests. The drug ivermectin is widely used in the treatment of strongyloidiasis.
It is thought to affect 30–100 million people worldwide, mainly in tropical and subtropical countries. Worldwide efforts are aimed at eradicating the infection in high-risk groups. Strongyloidiasis was first described in France in 1876.
Strongyloides infection occurs in five forms. On acquiring the infection, there may be respiratory symptoms (Löffler's syndrome). The infection may then become chronic with mainly digestive symptoms. On reinfection (when larvae migrate through the body), there may be respiratory, skin and digestive symptoms. Finally, the hyperinfection syndrome causes symptoms in many organ systems, including the
Waterhouse-Friderichsen syndrome (WFS) or hemorrhagic adrenalitis or Fulminant meningococcemia, is defined as adrenal gland failure due to bleeding into the adrenal glands, caused by severe bacterial infection (most commonly the meningococcus Neisseria meningitidis).
The bacterial infection leads to massive hemorrhage into one or (usually) both adrenal glands. It is characterized by overwhelming bacterial infection meningococcemia leading to massive blood invasion, organ failure, coma, low blood pressure and shock, disseminated intravascular coagulation (DIC) with widespread purpura, rapidly developing adrenocortical insufficiency and death.
Multiple species of bacteria can be associated with the condition:
Routine vaccination against meningococcus is recommended by the Centers for Disease Control for all 11-18 year olds and people who have poor splenic function (who, for example, have had their spleen removed or who have sickle-cell disease which damages the spleen), or who have certain immune disorders, such as a complement deficiency.
WFS is the most severe form of meningococcal septicemia. The onset of the illness is nonspecific with fever, rigors, vomiting, and headache. Soon
Chlamydia suis is a member of the genus Chlamydia. C. suis has only been isolated from swine, in which it may be endemic. Glycogen has been detected in Chlamydia suis inclusions in infected swine tissues and in cell culture. C. suis is associated with conjunctivitis, enteritis and pneumonia in swine (Rogers & Andersen, 1996; Rogers et al., 1996).
Some strains have enhanced resistance to sulfadiazine and tetracycline (Andersen & Rogers, 1998; Rockey et al., 2004; Pignanelli & Shurdhi, 2011). Several strains of C. suis are known to have an extrachromosomal plasmid, pCS. C. suis strains are somewhat more diverse than are other chlamydial species. The deduced ompA gene products of various Chlamydia suis strains contain vs4 epitopes TLNPTIAG(A.K.T)G(D.K.N.T), TWNPTIAGAGS or TLNPTISGKGQ. These epitopes are identical or nearly identical to the Chlamydia MOMP core epitopes NPTI, TLNPTI, LNPTIA or LNPTI, which are recognized by Chlamydia trachomatis vs4 mAbs. They are also identical or nearly identical to TIAGAGD and IAGAG epitopes, which are recognized by C. trachomatis B-serogroup mAbs (Batteiger et al., 1996).
Fasciolopsiasis results from an infection by the trematode Fasciolopsis buski, the largest intestinal fluke of humans (up to 7.5 cm in length).
Most infections are light and asymptomatic. In heavy infections, symptoms can include abdominal pain, chronic diarrhea, anemia, ascites, toxemia, allergic responses, sensitization caused by the absorption of the worms' allergenic metabolites (may eventually cause death of patient), and intestinal obstruction.
Microscopic identification of eggs, or more rarely of the adult flukes, in the stool or vomitus is the basis of specific diagnosis. The eggs are indistinguishable from those of Fasciola hepatica.
The parasite infects an amphibic snail (Segmentina nitidella, Segmentina hemisphaerula, Hippeutis schmackerie, Gyraulus, Lymnaea, Pila, Planorbis (Indoplanorbis)) after being released by infected feces; from this intermediate host, metacercaria infest on aquatic plants, which are eaten raw by pigs and humans. Also, the water is possibly infective when drunk unheated ("Encysted cercariae exist not only on aquatic plants, but also on the surface of the water.")
Prevention can be easily achieved by immersion of vegetables in boiling water for a
Severe acute respiratory syndrome (SARS, /ˈsɑrz/ SARZ) is a viral respiratory disease in humans which is caused by the SARS coronavirus (SARS-CoV). Between November 2002 and July 2003, an outbreak of SARS in Hong Kong nearly became a pandemic, with 8,422 cases and 916 deaths worldwide (10.9% fatality) according to the World Health Organization. Within weeks, SARS spread from Hong Kong to infect individuals in 37 countries in early 2003.
As of today, the spread of SARS has been fully contained, with the last infected human case seen in June 2003 (disregarding a laboratory-induced infection case in 2004). However, SARS is not claimed to have been eradicated (unlike smallpox), as it may still be present in its natural host reservoirs (animal populations) and may potentially return into the human population in the future.
The fatality of SARS is less than 1% for people aged 24 or younger, 6% for those 25 to 44, 15% for those 45 to 64, and more than 50% for those over 65. For comparison, the fatality of influenza is usually under 0.03% (primarily among the elderly), but rose to 2% during the most severe pandemic to date.
Initial symptoms are flu-like and may include: fever, myalgia,
Transmissible mink encephalopathy (TME) is rare sporadic disease that affects the central nervous system of ranch-raised mink. It is classified as a transmissible spongiform encephalopathy, believed to be caused by proteins called prions. This disease is only known to affect adult mink.
This illness has a minimum incubation period of 7 months with a maximum incubation period of 12 months. This disease results in mortality of adult animals.
Clinical signs of TME include the characteristic behavioural changes such as confusion, loss of cleanliness, and aimless circling. Affected animals show signs of weight loss, might develop matted fur, hind-quarter ataxia and arching its tail over its back. Seizures may very rarely occur. Near-death stages include the animals showing signs of drowsiness and unresponsiveness.
There are currently no tests to detect signs of this illness in live animals. However, veterinary pathologists can confirm this illness by microscopic examination of the brain tissue in animals suspected to have died of this disease, where they expect to detect areas of distinct sponge-like formations, or by the identification of the prion protein in these tissue samples.
Cat scratch disease (CSD) (also known as "Cat scratch fever", "Teeny's Disease", "Inoculation lymphoreticulosis", and "Subacute regional lymphadenitis") is a usually benign infectious disease caused by the intracellular bacterium Bartonella henselae. It is most commonly found in children following a scratch or bite from a cat by about one to two weeks. It was first discovered in 1889 by Henri Parinaud.
Manifestations of cat scratch disease can be divided into classic and atypical.
Classic cat scratch disease presents as tender and swollen regional lymph nodes, a condition referred to as regional lymphadenopathy. There may be a papule at the site of initial infection. While some patients have fever and other systemic symptoms, many do not. Other associated complaints include headache, chills, backache and abdominal pain. It may take 7 to 14 days, or as long as two months, before symptoms appear. Most cases are benign and self-limiting, but lymphadenopathy may persist for several months after other symptoms disappear. In general, the prognosis is favorable. In temperate climates, most cases occur in autumn and winter. The disease usually resolves spontaneously, with or without
Cheyletiella is a genus of mites that live on the skin surface of dogs, cats, rabbits, and humans.
The adult mites are about 0.385 millimeters long, have eight legs with combs instead of claws, and have palpi that end in prominent hooks. They do not burrow into the skin, but live in the keratin level. Their entire 21-day life cycle is on one host. They cannot survive off the host for more than 10 days.
Cheyletiellosis (also known as Cheyletiella dermatitis)," is a mild dermatitis caused by mites of the genus Cheyletiella. It is also known as walking dandruff due to skin scales being carried by the mites.
Cheyletiellosis is seen more commonly in areas where fleas are less prevalent, because of the decreased use of flea products that are also efficacious for the treatment of this mite.
Cheyletiellosis is highly contagious. Transmission is by direct contact with an affected animal.
Symptoms in animals vary from no signs to intense itching, scales on the skin, and hair loss. The lesions are usually on the back of the animal. Symptoms in humans include multiple red, itchy bumps on the arms, trunk, and buttocks. Because humans are an irregular host for the mite, the symptoms usually go
Ludwig's angina, otherwise known as angina ludovici, is a serious, potentially life-threatening cellulitis, or connective tissue infection, of the floor of the mouth, usually occurring in adults with concomitant dental infections and if left untreated, may obstruct the airways, necessitating tracheotomy. It is named after the German physician, Wilhelm Friedrich von Ludwig who first described this condition in 1836. Other names include "angina Maligna" and "Morbus Strangularis".
Ludwig's angina should not be confused with angina pectoris, which is also otherwise commonly known as "angina". The word "angina" comes from the Greek word ankhon, meaning "strangling", so in this case, Ludwig's angina refers to the feeling of strangling, not the feeling of chest pain, though there may be chest pain in Ludwig's angina if the infection spreads into the retrosternal space.
If this condition persist for more than two weeks, fluids and rest are very helpful combined with antibiotics.
Dental infections account for approximately eighty percent of cases of Ludwig's angina. Mixed infections, due to both aerobes and anaerobes, are of the cellulitis associated with Ludwig's angina. Typically, these
Meningococcal disease, or Meningococcal meningitis, is an acute bacterial infection caused by the bacterium Neisseria meningitidis (also known as meningococcus) that causes inflammation of the membranes covering the brain and spinal cord.
This disease is hard to identify as it can appear in several different forms, depending on which part of the body the bacteria invade. There can be meningitis or septicaemia, or a combination of both.
Note: Meningitis is not the same as meningococcal disease. There are many different types of meningitis.
Most cases of meningococcal meningitis occur in children. Early recognition and treatment of anyone exposed to meningococcus is extremely important to prevent serious illness or death.
Nongonococcal urethritis (NGU) is an inflammation of the urethra that is not caused by gonorrheal infection.
For treatment purposes, doctors usually classify infectious urethritis in two categories: gonococcal urethritis, caused by gonorrhea, and nongonococcal urethritis (NGU).
There are many causes of NGU. This is in part due to the large variety of organisms living in the urinary tract. Ureaplasma urealyticum and Mycoplasma genitalium are some of the culprits.
The most common bacterial cause of NGU is Chlamydia trachomatis, but it can also be caused by Ureaplasma urealyticum, Haemophilus vaginalis, and Mycoplasma genitalium.
Herpes simplex virus (rare), Adenovirus,
Parasitic causes include Trichomonas vaginalis (rare).
Urethritis can be caused by mechanical injury (from a urinary catheter or a cystoscope), by an irritating chemical (antiseptics or some spermicides).
The symptoms of urethritis can include pain or a burning sensation upon urination (dysuria), a white/cloudy discharge and a feeling that one needs to pass urine frequently. For men, the signs and symptoms are discharge from the penis, burning or pain when urinating, itching, irritation, or tenderness, and underwear
Swine brucellosis is a zoonosis affecting pigs, caused by the bacteria Brucella suis. The disease typically causes chronic inflammatory lesions in the reproductive organs of susceptible animals or orchitis and may even affect joints and other organs. The most common symptom is abortion in pregnant susceptible hosts at any stage of gestation. Other manifestations are temporary or permanent sterility, lameness, posterior paralysis, spondylitis, and abscess formation. It is transmitted mainly by ingestion of infected tissues or fluids, semen during breeding, and suckling infected animals. In humans, it can cause undulant fever.
Since brucellosis threatens food supply and cause undulant fever, Brucella suis and other Brucella species (B. melitensis, B. abortis, B. ovis, B. canis) are recognized as potential agricultural, civilian, and military bioterrorism agents.
B. suis are gram-negative, facultative intracellular coccobacilli and therefore are capable of growing and reproducing inside of host cells, specifically phagocytic cells. They are also non-spore-forming, non-capsulated, and non-motile. Flagellar genes, however, are present in the B. suis genome, but thought to be cryptic
Tetanus (from Ancient Greek: τέτανος tetanos "taut", and τείνειν teinein "to stretch")is a medical condition characterized by a prolonged contraction of skeletal muscle fibers. The primary symptoms are caused by tetanospasmin, a neurotoxin produced by the Gram-positive, rod-shaped, obligate anaerobic bacterium Clostridium tetani.
Infection generally occurs through wound contamination and often involves a cut or deep puncture wound. As the infection progresses, muscle spasms develop in the jaw (thus the name "lockjaw") and elsewhere in the body. Infection can be prevented by proper immunization and by post-exposure prophylaxis.
Tetanus often begins with mild spasms in the jaw muscles (lockjaw). The spasms can also affect the chest, neck, back, and abdominal muscles. Back muscle spasms often cause arching, called opisthotonos. Sometimes the spasms affect muscles that help with breathing, which can lead to breathing problems.
Prolonged muscular action causes sudden, powerful, and painful contractions of muscle groups. This is called tetany. These episodes can cause fractures and muscle tears. Other symptoms include drooling, excessive sweating, fever, hand or foot spasms,
Trichomoniasis, sometimes referred to as "trich", is a common cause of vaginitis. It is a sexually transmitted disease, and is caused by the single-celled protozoan parasite Trichomonas vaginalis producing mechanical stress on host cells and then ingesting cell fragments after cell death. Trichomoniasis is primarily an infection of the urogenital tract; the most common site of infection is the urethra and the vagina in women.
Typically, only women experience symptoms associated with Trichomonas infection. Symptoms include inflammation of the cervix (cervicitis), urethra (urethritis), and vagina (vaginitis) which produce an itching or burning sensation. Discomfort may increase during intercourse and urination. There may also be a yellow-green, itchy, frothy, foul-smelling ("fishy" smell) vaginal discharge. In rare cases, lower abdominal pain can occur. Symptoms usually appear in women within 5 to 28 days of exposure. In many cases, men may hold the parasite for some years without any signs (dormant). Some sexual health specialists have stated that the condition can probably be carried in the vagina for years, despite standard tests being negative. While symptoms are most common in
Candidiasis or thrush is a fungal infection (mycosis) of any of the Candida species (all yeasts), of which Candida albicans is the most common. Also commonly referred to as a yeast infection, candidiasis is also technically known as candidosis, moniliasis, and oidiomycosis.
Candidiasis encompasses infections that range from superficial, such as oral thrush and vaginitis, to systemic and potentially life-threatening diseases. Candida infections of the latter category are also referred to as candidemia and are usually confined to severely immunocompromised persons, such as cancer, transplant, and AIDS patients, as well as nontrauma emergency surgery patients.
Superficial infections of skin and mucosal membranes by Candida causing local inflammation and discomfort are common in many human populations. While clearly attributable to the presence of the opportunistic pathogens of the genus Candida, candidiasis describes a number of different disease syndromes that often differ in their causes and outcomes.
Candidiasis may be divided into the following types:
Symptoms of candidiasis vary depending on the area affected. Most candidial infections result in minimal complications such as
Hepatitis A (formerly known as infectious hepatitis and epidemical virus) is an acute infectious disease of the liver caused by the hepatitis A virus (Hep A), an RNA virus, usually spread by the fecal-oral route; transmitted person-to-person by ingestion of contaminated food or water or through direct contact with an infectious person. Tens of millions of individuals worldwide are estimated to become infected with Hep A each year. The time between infection and the appearance of the symptoms (the incubation period) is between two and six weeks and the average incubation period is 28 days.
In developing countries, and in regions with poor hygiene standards, the incidence of infection with this virus is high and the illness is usually contracted in early childhood. As incomes rise and access to clean water increases, the incidence of HAV decreases. Hepatitis A infection causes no clinical signs and symptoms in over 90% of infected children and since the infection confers lifelong immunity, the disease is of no special significance to those infected early in life. In Europe, the United States and other industrialized countries, on the other hand, the infection is contracted primarily
Late congenital syphilis is a subset of cases of congenital syphilis. By definition, it occurs in children at or greater than 2 years of age who acquired the infection trans-placentally.
A frequently-found group of symptoms is Hutchinson's triad, which consists of Hutchinson's teeth (notched incisors), keratitis and deafness and occurs in 63% of cases.
Treatment (with penicillin) before the development of late symptoms is essential.
Late congenital syphilitic oculopathy is a disease of the eye, a manifestation of late congenital syphilis. It can appear as:
Congenital syphilis is categorized by the age of the child. Early congenital syphilis occurs in children under 2 years old, and late congenital syphilis in children at or greater that 2 years old. Manifestations of late congenital syphilis are similar to those of secondary syphilis and tertiary syphilis in adults.
Measles (also sometimes known as English measles), also known as morbilli, is an infection of the respiratory system caused by a virus, specifically a paramyxovirus of the genus Morbillivirus. Morbilliviruses, like other paramyxoviruses, are enveloped, single-stranded, negative-sense RNA viruses. Symptoms include fever, cough, runny nose, red eyes and a generalized, maculopapular, erythematous rash.
Measles is spread through respiration (contact with fluids from an infected person's nose and mouth, either directly or through aerosol transmission), and is highly contagious—90% of people without immunity sharing living space with an infected person will catch it. An asymptomatic incubation period occurs nine to twelve days from initial exposure and infectivity lasts from two to four days prior, until two to five days following the onset of the rash (i.e. four to nine days infectivity in total).
The classical signs and symptoms of measles include four-day fevers and the three Cs — cough, coryza (head cold), conjunctivitis (red eyes), fever, anorexia, and rashes. The fever may reach up to 40 °C (104 °F). Koplik's spots seen inside the mouth are pathognomonic (diagnostic) for measles,
Tularemia (also known as Pahvant Valley plague, rabbit fever, deer fly fever, and Ohara's fever) is a serious infectious disease caused by the bacterium Francisella tularensis. A Gram-negative, nonmotile coccobacillus, the bacterium has several subspecies with varying degrees of virulence. The most important of those is F. tularensis tularensis (Type A), which is found in lagomorphs (rabbits and similar animals) in North America, and it is highly virulent in humans and domestic rabbits. F. tularensis palaearctica (Type B) occurs mainly in aquatic rodents (beavers, muskrats) in North America and in hares and small rodents in northern Eurasia. It is less virulent for humans and rabbits. The primary vectors are ticks and deer flies, but the disease can also be spread through other arthropods. The disease is named after Tulare County, California.
Depending on the site of infection, tularemia has six characteristic clinical symptoms: ulceroglandular (the most common type representing 75% of all forms), glandular, oropharyngeal, pneumonic, oculoglandular, and typhoidal.
The incubation period for tularemia is one to 14 days; most human infections become apparent after three to five days.
White-nose syndrome (WNS) is a poorly understood disease associated with the deaths of at least 5.7 million to 6.7 million North American bats. The condition, named for a distinctive fungal growth around the muzzles and on the wings of hibernating bats, was first identified in a cave in Schoharie County, New York, USA, in February 2006. It has rapidly spread and as of spring 2010, the condition had been found in over 115 caves and mines ranging mostly throughout the Northeastern US and as far south as Alabama and west to Missouri and into four Canadian provinces.
According to laboratory research in late 2011, the syndrome appears to be caused by a fungus called Geomyces destructans, but no obvious treatment or means of preventing transmission is known. The mortality rate of some species have been observed at 95%.
The US Fish & Wildlife Service (USFWS) has called for a moratorium on caving activities in the affected areas, and strongly recommends that any clothing or equipment used in such areas be decontaminated after each use.
The National Speleological Society (NSS) maintains an up-to-date page to keep cavers apprised of current events and advisories.
The fungus Geomyces
Babesiosis is a malaria-like parasitic disease caused by infection with Babesia, a genus of protozoal piroplasms. After trypanosomes, Babesia is thought to be the second most common blood parasites of mammals, and they can have a major impact on health of domestic animals in areas without severe winters. Human babesiosis is uncommon, but reported cases have risen recently because of expanded medical awareness.
Most cases of Babesia infection are asymptomatic, but can include mild fevers and diarrhea. The symptoms are often unnoticed or unexplained. In more severe cases, there are symptoms similar to malaria, with fevers up to 40.5°C (105°F), shaking chills, and severe anemia (hemolytic anemia). Organ failure may follow, including adult respiratory distress syndrome. Severe cases occur mostly in people who have had their spleen removed surgically. Severe cases are also more likely to occur in the very young, very old, and persons with immunodeficiency, such as HIV/AIDS patients.
A reported increase in babesiosis diagnoses in the 2000s is thought to be caused by more widespread testing and higher numbers of people with immunodeficiencies coming in contact with ticks, the disease
Bacterial fruit blotch (BFB) is a disease of watermelon and other cucurbit crops caused by bacterium Acidovorax avenae subsp. citrulli. The disease can be seed borne and is first noticed as small water-soaked lesions on seedlings. Inoculum can also originate on volunteer and wild cucurbits near fields and transplant operations. Bacterial fruit blotch can cause crop losses if allowed to progress in fields. Prevention is possible via several methods.
The best prevention against bacterial fruit blotch is to grow cucurbits in areas of the world that are not susceptible to the disease due to unfavorable environmental conditions. If this is not possible, having seed tested via a grow out, sweat box, or polymerase chain reaction method to ensure that it is clean before planting is a good idea. Several companies test seed with these methods, such as STA, Seminis, and Syngenta.
Erythema infectiosum or fifth disease is one of several possible manifestations of infection by erythrovirus, previously called parvovirus B19. The disease is also referred to as slapped cheek syndrome, slapcheek, slap face or slapped face. In Japan the disease is called 'apple sickness' or 'ringo-byou' (りんご病）in reference to the symptom of facial redness. In Hungary it is called "butterfly pox" as the red cheeks look like the wings of a butterfly.
Bright red cheeks are a defining symptom of the infection in children (hence the name "slapped cheek disease"). Occasionally the rash will extend over the bridge of the nose or around the mouth. In addition to red cheeks, children often develop a red, lacy rash on the rest of the body, with the upper arms and legs being the most common locations. The rash typically lasts a couple of days and may itch; some cases have been known to last for several weeks. Patients are usually no longer infectious once the rash has appeared.
Teenagers and adults may present with a self-limited arthritis. It manifests in painful swelling of the joints that feels similar to arthritis. Older children and adults with fifth disease may have difficulty in walking
Hantaviruses are negative sense RNA viruses in the Bunyaviridae family. Humans may be infected with hantaviruses through urine, saliva or contact with rodent waste products. Some hantaviruses cause potentially fatal diseases in humans, such as hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS), but others have not been associated with human disease.
Human infections of hantaviruses have almost entirely been linked to human contact with rodent excrement, but recent human-to-human transmission has been reported with the Andes virus in South America. The name hantavirus is derived from the Hantan River area in South Korea, which provided the founding member of the group: Hantaan virus (HTNV), isolated in the late 1970s by Ho-Wang Lee and colleagues. HTNV is one of several hantaviruses that cause HFRS, formerly known as Korean hemorrhagic fever.
The hantaviruses are a relatively newly discovered genus of viruses. Several thousand United Nations soldiers became ill with "Korean haemorrhagic fever" (now called HFRS) during the Korean War. This outbreak sparked a 25-year search for the etiologic agent. The isolation of Hantaan virus, or HTNV, was reported
Q fever is a disease caused by infection with Coxiella burnetii, a bacterium that affects humans and other animals. This organism is uncommon, but may be found in cattle, sheep, goats and other domestic mammals, including cats and dogs. The infection results from inhalation of a spore-like small cell variant, and from contact with the milk, urine, feces, vaginal mucus, or semen of infected animals. Rarely, the disease is tick borne. The incubation period is 9–40 days. A human being can be infected by a single bacterium. The bacterium is an obligate intracellular pathogen.
It was first described by Edward Holbrook Derrick in abattoir workers in Brisbane, Queensland, Australia. The "Q" stands for "query" and was applied at a time when the causative agent was unknown; it was chosen over suggestions of "abattoir fever" and "Queensland rickettsial fever", to avoid directing negative connotations at either the cattle industry or the state of Queensland.
The pathogen of Q fever was discovered in 1937, when Frank Macfarlane Burnet and Mavis Freeman isolated the bacterium from one of Derrick’s patients. It was originally identified as a species of Rickettsia. H.R. Cox and Gordon Davis
Trench fever (also known as "Five day fever", "Quintan fever" (febris Quintana in Latin), "Urban trench fever") is a moderately serious disease transmitted by body lice. It infected armies in Flanders, France, Poland, Galicia, Italy, Salonika, Macedonia, Mesopotamia, and Egypt in World War I (three noted sufferers being the authors J.R.R. Tolkien, A. A. Milne, and C.S. Lewis), and the German army in Russia during World War I. From 1915 to 1918 between one-fifth and one-third of all British troops reported ill had trench fever while about one-fifth of ill German and Austrian troops had the disease. The disease persists among the homeless. Outbreaks have been documented, for example, in Seattle and Baltimore in the United States among injection drug users and in Marseille, France, and Burundi.
Trench fever is also called Wolhynia fever, shin bone fever, quintan fever, five-day fever, Meuse fever, His disease and His-Werner disease (after Wilhelm His, Jr. and Heinrich Werner).
The disease is caused by the bacterium Bartonella quintana (older names: Rochalimea quintana, Rickettsia quintana), found in the stomach walls of the body louse. Bartonella quintana is closely related to
Epidemic typhus (also called "camp fever", "jail fever", "hospital fever", "ship fever", "famine fever", "putrid fever", "petechial fever", "Epidemic louse-borne typhus," and "louse-borne typhus") is a form of typhus so named because the disease often causes epidemics following wars and natural disasters. The causative organism is Rickettsia prowazekii, transmitted by the human body louse (Pediculus humanus corporis). Feeding on a human who carries the bacillus infects the louse. R. prowazekii grows in the louse's gut and is excreted in its feces. The disease is then transmitted to an uninfected human who scratches the louse bite (which itches) and rubs the feces into the wound. The incubation period is one to two weeks. R. prowazekii can remain viable and virulent in the dried louse feces for many days. Typhus will eventually kill the louse, though the disease will remain viable for many weeks in the dead louse.
Symptoms include severe headache, a sustained high fever, cough, rash, severe muscle pain, chills, falling blood pressure, stupor, sensitivity to light, and delirium. A rash begins on the chest about five days after the fever appears, and spreads to the trunk and
Oroya fever or Carrion's Disease is an infectious disease produced by Bartonella bacilliformis infection.
It is named for Daniel Alcides Carrión.
Carrion's disease has been known since Pre-Inca times. Numerous artistic representations in clay (called "huacos") of the chronic phase have been found in endemic areas. The Spanish chronist, Garcilazo De La Vega described a disease with warts in Spanish troops during the conquest of Inca Empire, in Coaque-Ecuador. For a long time it was thought that the disease was endemic only in Peru and that it had only one phase, the "Peruvian wart" or "verruga peruana"
In 1875 an outbreak, characterized by fever and anemia occurred in the region of construction of the railroad line between Lima and Oroya. This is the source of the name "oroya fever" sometimes used to describe acute bartonellosis.
In August 1885, Daniel Alcides Carrión, a Peruvian medical student, inoculated himself with material taken from a verruga lesion of a chronic patient (Carmen Paredes), with the help of a local physician (Evaristo Chavez). After 3 weeks he developed classic symptoms of the acute phase of the disease, thus establishing a common etiology (cause) for these two
Human immunodeficiency virus (HIV) is a lentivirus (a member of the retrovirus family) that causes acquired immunodeficiency syndrome (AIDS), a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive.
HIV infects vital cells in the human immune system such as helper T cells (specifically CD4 T cells), macrophages, and dendritic cells. HIV infection leads to low levels of CD4 T cells through three main mechanisms: First, direct viral killing of infected cells; second, increased rates of apoptosis in infected cells; and third, killing of infected CD4 T cells by CD8 cytotoxic lymphocytes that recognize infected cells. When CD4 T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections.
HIV is a member of the genus Lentivirus, part of the family of Retroviridae. Lentiviruses have many morphologies and biological properties in common. Many species are infected by lentiviruses, which are characteristically responsible for long-duration illnesses with a long incubation period. Lentiviruses are transmitted
Amoebiasis, or Amebiasis, refers to infection caused by the amoeba Entamoeba histolytica. The term Entamoebiasis is occasionally seen but is no longer in use; it refers to the same infection. Likewise amoebiasis is sometimes incorrectly used to refer to infection with other amoebae, but strictly speaking it should be reserved for Entamoeba histolytica infection. Other amoebae infecting humans include:
Except for Dientamoeba, the parasites above are not thought to cause disease.
A gastrointestinal infection that may or may not be symptomatic and can remain latent in an infected person for several years, amoebiasis is estimated to cause 70,000 deaths per year world wide. Symptoms can range from mild diarrhea to dysentery with blood and mucus in the stool. E. histolytica is usually a commensal organism. Severe amoebiasis infections (known as invasive or fulminant amoebiasis) occur in two major forms. Invasion of the intestinal lining causes amoebic dysentery or amoebic colitis. If the parasite reaches the bloodstream it can spread through the body, most frequently ending up in the liver where it causes amoebic liver abscesses. Liver abscesses can occur without previous development of
Chickenpox (or chicken pox) is a highly contagious disease caused by primary infection with varicella zoster virus (VZV). It usually starts with vesicular skin rash mainly on the body and head rather than at the periphery and becomes itchy, raw pockmarks, which mostly heal without scarring. On examination, the observer typically finds lesions at various stages of healing.
Chickenpox is an airborne disease spread easily through coughing or sneezing of ill individuals or through direct contact with secretions from the rash. A person with chickenpox is infectious one to two days before the rash appears. They remain contagious until all lesions have crusted over (this takes approximately six days). Immunocompromised patients are contagious during the entire period as new lesions keep appearing. Crusted lesions are not contagious.
Chickenpox has been observed in other primates, including chimpanzees and gorillas.
There are several theories regarding the origin of the term chicken pox. It is often stated to be a modification of chickpeas (based on resemblance of the vesicles to chickpeas), or due to the rash resembling chicken pecks. Other theories include the designation chicken for a
Fasciolosis also known as Fascioliasis, Fasciolasis, distomatosis and liver rot, is an important helminth disease caused by two trematodes Fasciola hepatica (the common liver fluke) and Fasciola gigantica. This disease belongs to the plant-borne trematode zoonoses. In Europe, the Americas and Oceania only F. hepatica is a concern, but the distributions of both species overlap in many areas of Africa and Asia.
The definitive host range is very broad and includes many herbivorous mammals, including humans. The life cycle includes freshwater snails as an intermediate host of the parasite. Recently, worldwide losses in animal productivity due to fasciolosis were conservatively estimated at over US$3.2 billion per annum. In addition, fasciolosis is now recognized as an emerging human disease: the World Health Organization (WHO) has estimated that 2.4 million people are infected with Fasciola, and a further 180 million are at risk of infection.
Fasciolosis is caused by two digenetic trematodes F. hepatica and F. gigantica. Adult flukes of both species are localized in the bile ducts of the liver or gallbladder. F. hepatica measures 2 to 3 cm and has a cosmopolitan distribution. F.
Fatal familial insomnia (FFI) is a very rare autosomal dominant inherited prion disease of the brain. It is almost always caused by a mutation to the protein PrP, but can also develop spontaneously in patients with a non-inherited mutation variant called sporadic Fatal Insomnia (sFI). FFI has no known cure and involves progressively worsening insomnia, which leads to hallucinations, delirium, and confusional states like that of dementia. The average survival span for patients diagnosed with FFI after the onset of symptoms is 18 months.
The mutated protein, called PrP, has been found in just 40 families worldwide, affecting about 100 people; if only one parent has the gene, the offspring have a 50% chance of inheriting it and developing the disease. The first recorded victim was an Italian man, deceased in Venice in the year 1765.
Gene PRNP that provides instructions for making the prion protein PrP is located on the short (p) arm of chromosome 20 at position p13. Both FFI patients and those with Creutzfeldt-Jakob disease carry a mutation at codon 178 of the prion protein gene. FFI is invariably linked to the presence of the methionine codon at position 129 of the mutant allele,
A plantar wart (also known as "Verruca plantaris") is a wart caused by the human papillomavirus (HPV) occurring on the sole or toes of the foot. (HPV infections in other locations are not plantar; see human papillomavirus.) Plantar warts are usually self-limiting, but treatment is generally recommended to lessen symptoms (which may include pain), decrease duration, and reduce transmission. Plantar warts are almost unknown in habitually barefoot cultures and people, this is because walking barefoot for extended periods of time strengthens the skin and keeps it dry and uncompromised as well as wearing off the virus through friction on the soles of the feet, preventing infection. While infection occurs in an estimated 7–10% of the US population, plantar warts tend to affect only 0.29% of people who have never worn shoes
Infection typically occurs from moist walking surfaces such as showers or swimming pools. The virus can survive many months without a host, making it highly contagious to people who habitually wear shoes.
Plantar warts are benign epithelial tumors caused by infection by human papilloma virus types 1, 2, 4, or 63. These types are classified as clinical (visible
Varicella zoster virus (VZV) is one of eight herpes viruses known to infect humans and other vertebrates. It commonly causes chicken-pox in children and adults and herpes zoster (shingles) in adults and rarely in children.
Varicella-zoster virus is known by many names, including: chickenpox virus, varicella virus, zoster virus, and human herpes virus type 3 (HHV-3).
Primary VZV infection results in chickenpox (varicella), which may rarely result in complications including encephalitis or pneumonia. Even when clinical symptoms of chickenpox have resolved, VZV remains dormant in the nervous system of the infected person (virus latency), in the trigeminal and dorsal root ganglia. In about 10–20% of cases, VZV reactivates later in life producing a disease known as shingles or herpes zoster. VZV is more likely to reactivate in patients with severely compromised immune systems, such as AIDS patients. Serious complications of shingles include postherpetic neuralgia, zoster multiplex, myelitis, herpes ophthalmicus, or zoster sine herpete. Ramsay Hunt syndrome; VZV rarely effects the geniculate ganglion giving lesions that follow specific branches of the facial nerve. Symptoms may include
The viral hemorrhagic (or haemorrhagic) fevers (VHFs) are a diverse group of animal and human illnesses that may be caused by five distinct families of RNA viruses: the families Arenaviridae, Filoviridae, Bunyaviridae, Flaviviridae, and Rhabdoviridae. All types of VHF are characterized by fever and bleeding disorders and all can progress to high fever, shock and death in many cases. Some of the VHF agents cause relatively mild illnesses, such as the Scandinavian nephropathia epidemica, while others, such as the African Ebola virus, can cause severe, life-threatening disease.
Five families of RNA viruses have been recognised as being able to cause this syndrome.
Signs and symptoms of VHFs include (by definition) fever and bleeding diathesis. Manifestations of VHF often also include flushing of the face and chest, petechiae, frank bleeding, edema, hypotension, and shock. Malaise, myalgias, headache, vomiting, and diarrhea occur frequently. Definitive diagnosis is usually made at a reference laboratory with advanced biocontainment capabilities.
The findings of laboratory investigation vary somewhat between the viruses but in general there is a decrease in the total white cell count
Leptospirosis (also known as Weil's syndrome, canicola fever, canefield fever, nanukayami fever, 7-day fever, Rat Catcher's Yellows, Fort Bragg fever, black jaundice, and Pretibial fever) is caused by infection with bacteria of the genus Leptospira and affects humans as well as other animals.
Leptospirosis is among the world's most common diseases transmitted to people from animals. The infection is commonly transmitted to humans by allowing water that has been contaminated by animal urine to come in contact with unhealed breaks in the skin, the eyes, or with the mucous membranes. Outside of tropical areas, leptospirosis cases have a relatively distinct seasonality with most cases occurring in spring and autumn.
Leptospirosis is caused by a spirochaete bacterium called Leptospira spp. There are at least five serotypes of importance in the United States and Canada, all of which cause disease in dogs (Icterohaemorrhagiae, Canicola, Pomona, Grippotyphosa, and Bratislava).
There are other (less common) infectious strains. Genetically different leptospira organisms may be identical serologically and vice versa. Hence, an argument exists on the basis of strain identification. The
Typhoid fever, also known as typhoid, is a common worldwide bacterial disease, transmitted by the ingestion of food or water contaminated with the feces of an infected person, which contain the bacterium Salmonella typhi, serotype Typhi.
The disease has received various names, such as gastric fever, abdominal typhus, infantile remittant fever, slow fever, nervous fever or pythogenic fever. The name "typhoid" means "resembling typhus" and comes from the neuropsychiatric symptoms common to typhoid and typhus. Despite this similarity of their names, typhoid fever and typhus are distinct diseases and are caused by different species of bacteria.
The impact of this disease fell sharply with the application of 20th century sanitation techniques.
Classically, the course of untreated typhoid fever is divided into four individual stages, each lasting approximately one week. In the first week, the temperature rises slowly and fever fluctuations are seen with relative bradycardia, malaise, headache, and cough. A bloody nose (epistaxis) is seen in a quarter of cases and abdominal pain is also possible. There is leukopenia, a decrease in the number of circulating white blood cells, with
Diphyllobothriasis is the infection caused by the tapeworm Diphyllobothrium.
Diphyllobothriasis occurs in areas where lakes and rivers coexist with human consumption of raw or undercooked freshwater fish. Such areas are found in Europe, newly independent states of the former Soviet Union, North America, Asia, Uganda, Peru (because of Ceviche), and Chile. It is particularly common in Japan, because of Sushi or Sashimi.
Around the middle of the 20th century in Japan, before advancements in refrigeration, many sushi/sashimi connoisseurs suffered great morbidity and mortality from Diphyllobothrium after eating unrefrigerated sashimi. Through research in parasitology, scientists came to realize that the primary cause was the relatively favorable parasite-breeding conditions that raw fish offered.
The disease is rare in the United States. It was, however, once more common and was referred to as "Jewish housewife's disease" because Jewish housewives preparing the traditional "gefilte fish" frequently tasted the fish before it was cooked.
Diphyllobothriasis can last for decades if untreated. Most infections are asymptomatic. Manifestations may include abdominal discomfort, diarrhea,
Ecthyma gangrenosum is an infection of the skin typically caused by Pseudomonas aeruginosa. It presents as a round or oval lesion, 1 cm to 15 cm in diameter, with a halo of erythema. A necrotic center is usually present with a surrounding erythematous edge, representing where the organism invaded blood vessels and caused infarctions. These ulceritic lesions are single or multiple and heal with scar formation. The mechanism of tissue destruction is Pseudomonas exotoxin A, a toxin similar to Corynebacterium diphtheriae toxin that causes inactivation of elongation factor 2, although sepsis resulting from other gram negative bacteria can also cause this condition.
Dukes' disease or fourth disease is an exanthem.
It is named after Clement Dukes and is also known as Filatov’s disease (after Nil Filatov)
Some of these eruptions are characteristic of the causative virus, but in most cases one must be satisfied with the diagnosis of viral rash.
It was never associated with a specific pathogen, and the terms "fourth disease" and "Dukes' disease" are rarely used today.
In 1979 Keith Powell proposed equating it with the condition currently known as Staphylococcal scalded skin syndrome.
Signs and symptoms may include fever, nausea, vomiting, and diarrhea, along with typical viral symptoms of photophobia, lymphadenopathy, sore throat, and possibly encephalitis. The rash may appear at any time during the illness. It is usually generalised. The rash consists of erythematous maculopapules with areas of confluence. They may be urticarial, vesicular, or sometimes petechial. The palms and soles may be involved. The eruptions are more common in children than in adults. Usually, the rash fades without pigmentation or scaling.
Pasteurella multocida is a Gram-negative, nonmotile, penicillin-sensitive coccobacillus belonging to the Pasteurellaceae family. It can cause avian cholera in birds and a zoonotic infection in humans, which typically is a result of bites or scratches from domestic pets. Many mammals and fowl harbor it as part of their normal respiratory microbiota, displaying asymptomatic colonization.
Pasteurella multocida was first found in 1878 in cholera-infected birds. However, it was not isolated until 1880, by Louis Pasteur - the man in whose honor Pasteurella is named.. The bacterium is found in many environments, but the associated cholera outbreaks are usually found in central California, the Midwest, and Texas.
P. multocida causes disease in wild and domesticated animals, as well as humans. The bacterium can be found in fowl, felines, canines, rabbits, cattle and pigs. In birds, P. multocida causes avian cholera; the disease has been shown to follow migration routes, especially of snow geese. The P. multocida serotype-1 is most associated with avian cholera in North America, but the bacterium does not linger in wetlands for extended periods of time. . P. multocida causes atrophic
Pseudomembranous colitis, a cause of antibiotic-associated diarrhea (AAD), is an inflammation of the colon. It is often, but not always, caused by the bacterium Clostridium difficile. Because of this, the informal name C. difficile colitis is also commonly used. The illness is characterized by offensive-smelling diarrhea, fever, and abdominal pain. In severe cases, life-threatening complications can develop, such as toxic megacolon.
As noted above, pseudomembranous colitis is characterized by diarrhea, abdominal pain, and fever. Usually, the diarrhea is non-bloody, although blood may be present if the affected individual is taking blood thinners or has an underlying lower bowel condition such as hemorrhoids. Abdominal pain is almost always present and may be severe. So-called "peritoneal" signs (e.g., rebound tenderness) may be present. "Constitutional" signs such as fever, fatigue, and loss of appetite are prominent. In fact, one of the main ways of distinguishing pseudomembranous colitis from other antibiotic-associated diarrheal states is that patients with the former are sick. That is, they are often prostrate, lethargic, and in general look unwell. Their "sick" appearance
Tinea capitis (also known as "Herpes tonsurans", "Ringworm of the hair," "Ringworm of the scalp," "Scalp ringworm", and "Tinea tonsurans") is a superficial fungal infection (dermatophytosis) of the scalp. The disease is primarily caused by dermatophytes in the Trichophyton and Microsporum genera that invade the hair shaft. The clinical presentation is typically a single or multiple patches of hair loss, sometimes with a 'black dot' pattern (often with broken-off hairs), that may be accompanied by inflammation, scaling, pustules, and itching. Uncommon in adults, tinea capitis is predominantly seen in pre-pubertal children, more often in boys than girls.
At least eight species of dermatophytes are commonly associated with tinea capitis. Cases of Trichophyton infection predominate from Central America to the United States and in parts of Western Europe. Infections due to Microsporum species are mainly seen in South America, Southern and Central Europe, Africa and the Middle East. The disease is infectious and can be transmitted by humans, animals, or objects that harbor the fungus. Carrier states also exist where the fungus is present on the scalp but there are no clinical signs or
Hepatitis B is an infectious inflammatory illness of the liver caused by the hepatitis B virus (HBV) that affects hominoidea, including humans. Originally known as "serum hepatitis", the disease has caused epidemics in parts of Asia and Africa, and it is endemic in China. About a third of the world population has been infected at one point in their lives, including 350 million who are chronic carriers.
The virus is transmitted by exposure to infectious blood or body fluids such as semen and vaginal fluids, while viral DNA has been detected in the saliva, tears, and urine of chronic carriers. Perinatal infection is a major route of infection in endemic (mainly developing) countries. Other risk factors for developing HBV infection include working in a healthcare setting, transfusions, dialysis, acupuncture, tattooing, extended overseas travel, and residence in an institution. However, Hepatitis B viruses cannot be spread by holding hands, sharing eating utensils or drinking glasses, kissing, hugging, coughing, sneezing, or breastfeeding.
The acute illness causes liver inflammation, vomiting, jaundice and, rarely, death. Chronic hepatitis B may eventually cause cirrhosis and liver
Subacute sclerosing panencephalitis (SSPE) is a rare chronic, progressive encephalitis that affects primarily children and young adults, caused by a persistent infection measles virus (which can be a result of a mutation of the virus itself). No cure for SSPE exists, but the condition can be managed by medication if treatment is started at an early stage. Much of the work on SSPE has been performed by the National Institute of Neurological Disorders and Stroke (NINDS).
SSPE is also known as Dawson Disease, Dawson encephalitis and measles encephalitis. It should not be confused with acute disseminated encephalomyelitis which has a similar etiology but very different timing and course.
Characterized by a history of primary measles infection usually before the age of 2 years, followed by several asymptomatic years (6–15 on average), and then gradual, progressive psychoneurological deterioration, consisting of personality change, seizures, myoclonus, ataxia, photosensitivity, ocular abnormalities, spasticity, and coma.
A large number of nucleocapsids are produced in the neurons and the glial cells. In these cells the viral genes that encode envelope proteins have restricted expression.
Bacteremia (also bacteraemia or bacteræmia) is the presence of bacteria in the blood. The blood is normally a sterile environment, so the detection of bacteria in the blood (most commonly accomplished by blood cultures) is always abnormal.
Bacteria can enter the bloodstream as a severe complication of infections (like pneumonia or meningitis), during surgery (especially when involving mucous membranes such as the gastrointestinal tract), or due to catheters and other foreign bodies entering the arteries or veins (including intravenous drug abuse).
Bacteremia can have several consequences. The immune response to the bacteria can cause sepsis and septic shock, which has a relatively high mortality rate. Bacteria can also use the blood to spread to other parts of the body (which is called hematogenous spread), causing infections away from the original site of infection. Examples include endocarditis or osteomyelitis. Treatment is with antibiotics, and prevention with antibiotic prophylaxis can be given in situations where problems are to be expected.
Bacteremia is the presence of viable bacteria in the blood stream.
Bacteremia is different from sepsis (so-called blood poisoning or
Bovine spongiform encephalopathy (BSE), commonly known as mad cow disease, is a fatal neurodegenerative disease (encephalopathy) in cattle that causes a spongy degeneration in the brain and spinal cord. BSE has a long incubation period, about 30 months to 8 years, usually affecting adult cattle at a peak age onset of four to five years, all breeds being equally susceptible. In the United Kingdom, the country worst affected, more than 180,000 cattle have been infected and 4.4 million slaughtered during the eradication program.
The disease may be most easily transmitted to human beings by eating food contaminated with the brain, spinal cord or digestive tract of infected carcasses. However, it should also be noted that the infectious agent, although most highly concentrated in nervous tissue, can be found in virtually all tissues throughout the body, including blood. In humans, it is known as new variant Creutzfeldt–Jakob disease (vCJD or nvCJD), and by October 2009, it had killed 166 people in the United Kingdom, and 44 elsewhere. Between 460,000 and 482,000 BSE-infected animals had entered the human food chain before controls on high-risk offal were introduced in 1989.
Crimean–Congo hemorrhagic fever (CCHF) is a widespread tick-borne viral disease, a zoonosis of domestic animals and wild animals, that may affect humans. The pathogenic virus, especially common in East and West Africa, is a member of the Bunyaviridae family of RNA viruses. Clinical disease is rare in infected mammals, but commonly severe in infected humans, with a 30% mortality rate. Outbreaks of illness are usually attributable to handling infected animals or people.
Typically, after a 1–3 day incubation period following a tick bite (5–6 days after exposure to infected blood or tissues), flu-like symptoms appear, which may resolve after one week. In up to 75% of cases, however, signs of hemorrhage appear within 3–5 days of the onset of illness in case of bad containment of the first symptoms: first mood instability, agitation, mental confusion and throat petechiae, then soon nosebleeds, bloody urine and vomiting, and black stools. The liver becomes swollen and painful. Disseminated intravascular coagulation may occur as well as acute kidney failure and shock, and sometimes acute respiratory distress syndrome. Patients usually begin to show signs of recovery after 9–10 days from
Granuloma inguinale is a bacterial disease caused by Klebsiella granulomatis characterized by ulcerative genital lesions. It is endemic in many less developed regions. It is also known as donovanosis, granuloma genitoinguinale, granuloma inguinale tropicum, granuloma venereum, granuloma venereum genitoinguinale, lupoid form of groin ulceration, serpiginous ulceration of the groin, ulcerating granuloma of the pudendum and ulcerating sclerosing granuloma.
The disease often goes untreated because of the scarcity of medical treatment in the countries in which it is found. In addition, the painless genital ulcers can be mistaken for syphilis. The ulcers ultimately progress to destruction of internal and external tissue, with extensive leakage of mucus and blood from the highly vascular lesions. The destructive nature of donovanosis also increases the risk of superinfection by other pathogenic microbes.
The first known name for this condition was "serpiginous ulcer", which dates to 1882. The proper clinical designation for donovanosis is now "granuloma inguinale". A granuloma is a nodular type of inflammatory reaction, and inguinale refers to the inguinal region, which is commonly
Gnathostomiasis (also known as larva migrans profundus) is the human infection by the nematode (roundworm) Gnathostoma spinigerum and/or Gnathostoma hispidum, which infects vertebrates.
The following are commonly used terms when referring to gnathostomiasis
The first case of Gnathostoma was identified by Sir Richard Owen when inspecting the stomach of a young tiger that had died at London Zoo from a ruptured aorta. However it was not until 1889 that the first human case was described by Levison when he found the gnathostoma larva in an infested Thai woman. This delay in identification of the parasite in humans is due to the fact that humans are not a definitive host for this parasite making infection from this parasite rare. Gnathostomiasis infection is rare because the parasite must be digested when it has reached its third larvae stage, providing only a short time frame in which the parasite is capable of infecting humans. It is uncommon for the larvae to penetrate the skin of individuals exposed to contaminated food or water without ingestion.
Human gnathostomiasis is infection by the migrating third-stage larvae of any of five species of Gnathostoma, which is type of worm (more
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs. Meningitis can be life-threatening because of the inflammation's proximity to the brain and spinal cord; therefore the condition is classified as a medical emergency.
The most common symptoms of meningitis are headache and neck stiffness associated with fever, confusion or altered consciousness, vomiting, and an inability to tolerate light (photophobia) or loud noises (phonophobia). Children often exhibit only nonspecific symptoms, such as irritability and drowsiness. If a rash is present, it may indicate a particular cause of meningitis; for instance, meningitis caused by meningococcal bacteria may be accompanied by a characteristic rash.
A lumbar puncture diagnoses or excludes meningitis. A needle is inserted into the spinal canal to extract a sample of cerebrospinal fluid (CSF), that envelops the brain and spinal cord. The CSF is examined in a medical laboratory. The first treatment in acute meningitis consists of promptly
Miliary tuberculosis (also known as "disseminated tuberculosis", "tuberculosis cutis acuta generalisata", and "Tuberculosis cutis disseminata") is a form of tuberculosis that is characterized by a wide dissemination into the human body and by the tiny size of the lesions (1–5 mm). Its name comes from a distinctive pattern seen on a chest X-ray of many tiny spots distributed throughout the lung fields with the appearance similar to millet seeds—thus the term "miliary" tuberculosis. Miliary TB may infect any number of organs, including the lungs, liver, and spleen. It is a complication of 1–3% of all TB cases.
Miliary tuberculosis is a form of tuberculous infection in the lung that is the result of erosion of the infection into a pulmonary vein. Once the bacteria reach the left side of the heart and enter the systemic circulation, the result may be to seed organs such as the liver and spleen with said infection. Alternatively, the bacteria may enter the lymph node(s), drain into a systemic vein and eventually reach the right side of the heart. From the right side of the heart, the bacteria may seed—or re-seed as the case may be—the lungs, causing the eponymous "miliary" appearance.
The simian foamy virus (SFV) is a spumavirus closely related to the Human Immunodeficiency Virus, HIV, the virus that can lead to AIDS. Its discovery in primates has led to some speculation that HIV may have been spread to the human species in Africa through contact with blood from apes, monkeys, and through hunting bushmeat.
About 70–90% of non-human primates born in captivity have SFV. Animals with SFV do not display symptoms or become ill. However, recent research suggests that some primates that contract SFV would become pre-disposed to other viruses. People who have had contact with non-human primates can become infected with SFV.
Although the simian foamy virus is endemic in African apes and monkeys, there is not enough evidence that it causes any harm to the population. Its ability to cross over to humans was proven in 2004 by a joint United States and Cameroonian team which found the retrovirus in gorillas, mandrills and guenons; unexpectedly they also found it in 10 of 1,100 local Cameroon residents. Of those found infected the majority are males who had been bitten by a non-human primate.
While this only accounts for 1% of the population, this detail is alarming to some
Chlamydia infection (from the Greek, χλαμύδα meaning "cloak") is a common sexually transmitted infection (STI) in humans caused by the bacterium Chlamydia trachomatis. The term Chlamydia infection can also refer to infection caused by any species belonging to the bacterial family Chlamydiaceae. C. trachomatis is found only in humans. Chlamydia is a major infectious cause of human genital and eye disease. Chlamydia infection is one of the most common sexually transmitted infections worldwide; it is estimated that about 1 million individuals in the United States are infected with chlamydia.
C. trachomatis is naturally found living only inside human cells. Chlamydia can be transmitted during vaginal, anal, or oral sex, and can be passed from an infected mother to her baby during vaginal childbirth. Between half and three-quarters of all women who have a chlamydia infection of the cervix (cervicitis) have no symptoms and do not know that they are infected. In men, infection of the urethra (urethritis) is usually symptomatic, causing a white discharge from the penis with or without pain on urinating (dysuria). Occasionally, the condition spreads to the upper genital tract in women
Rheumatic fever is an inflammatory disease that occurs following a Streptococcus pyogenes infection, such as streptococcal pharyngitis or scarlet fever. Believed to be caused by antibody cross-reactivity that can involve the heart, joints, skin, and brain, the illness typically develops two to three weeks after a streptococcal infection. Acute rheumatic fever commonly appears in children between the ages of 6 and 15, with only 20% of first-time attacks occurring in adults. The illness is so named because of its similarity in presentation to rheumatism.
Modified Jones criteria were first published in 1944 by T. Duckett Jones, MD. They have been periodically revised by the American Heart Association in collaboration with other groups. According to revised Jones criteria, the diagnosis of rheumatic fever can be made when two of the major criteria, or one major criterion plus two minor criteria, are present along with evidence of streptococcal infection: elevated or rising antistreptolysin O titre or DNAase. Exceptions are chorea and indolent carditis, each of which by itself can indicate rheumatic fever.
Rheumatic fever is a systemic disease affecting the peri-arteriolar connective
Tuberculosis, MTB, or TB (short for tubercle bacillus) is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis typically attacks the lungs, but can also affect other parts of the body. It is spread through the air when people who have an active TB infection cough, sneeze, or otherwise transmit their saliva through the air. Most infections are asymptomatic and latent, but about one in ten latent infections eventually progresses to active disease which, if left untreated, kills more than 50% of those so infected.
The classic symptoms of active TB infection are a chronic cough with blood-tinged sputum, fever, night sweats, and weight loss (the latter giving rise to the formerly prevalent term "consumption"). Infection of other organs causes a wide range of symptoms. Diagnosis of active TB relies on radiology (commonly chest X-rays), as well as microscopic examination and microbiological culture of body fluids. Diagnosis of latent TB relies on the tuberculin skin test (TST) and/or blood tests. Treatment is difficult and requires administration of multiple antibiotics over a long period of
Zika fever is an illness caused by the Zika virus, a member of the family Flaviviridae. The fever and virus are named after the Ugandan forest where the virus was first isolated. The virus is commonly found in Africa but has also been found in Malaysia and Micronesia, including Yap Island. Symptoms are similar to dengue fever, but are milder in form and usually last four to seven days. Hemorrhagic manifestations have been documented in only one instance, hematospermia (red–brown fluid in ejaculate). Common symptoms include a maculopapular skin rash that starts on the face or trunk before moving to the rest of the body, conjunctivitis, joint pain, low-grade fevers and headache. It is generally believed that the virus is spread by mosquitoes, making vector control an essential element to disease control. A single instance of sexual transmission of Zika virus between humans was reported in April, 2011 by a university biologist bitten by mosquitoes while performing research in Senegal who after returning to the US unknowingly transmitted the Zika virus to his wife by vaginal intercourse before he became symptomatic.
Bacterial meningitis refers to meningitis that is caused by bacterial infection.
Bacterial meningitis is often associated with elevated levels of CSF total protein.
Bacterial meningitis may initially appear aseptic. Even though true aseptic meningitis cannot be caused by pyogenic bacteria, broad-spectrum antibiotic cover should be started as the consequences of misdiagnosing a bacterial meningitis are dire, and relatively easily avoided. For non-pyogenic bacteria, local sensitivities should be taken into account, but generally broad-spectrum is best. Some bacteria are normally sensitive to certain drugs - for example, rifampicin is good for Brucella.
While the choice of antibiotic sometimes differs based on the offending pathogen, treatment for bacterial meningitis always includes antibiotic drugs, often given intravenously. Dexamethasone has been proposed as a possible adjunct to treatment.
The common cold (also known as nasopharyngitis, rhinopharyngitis, acute coryza, or a cold) is a viral infectious disease of the upper respiratory tract which affects primarily the nose. Symptoms include coughing, sore throat, runny nose, and fever which usually resolve in seven to ten days, with some symptoms lasting up to three weeks. Well over 200 viruses are implicated in the cause of the common cold; the rhinoviruses are the most common.
Upper respiratory tract infections are loosely divided by the areas they affect, with the common cold primarily affecting the nose, the throat (pharyngitis), and the sinuses (sinusitis). Symptoms are mostly due to the body's immune response to the infection rather than to tissue destruction by the viruses themselves. The primary method of prevention is by hand washing with some evidence to support the effectiveness of wearing face masks.
No cure for the common cold exists, but the symptoms can be treated. It is the most frequent infectious disease in humans with the average adult contracting two to three colds a year and the average child contracting between six and twelve. These infections have been with humanity since antiquity.
Acute prostatitis is a serious bacterial infection of the prostate gland. This infection is a medical emergency. It should be distinguished from other forms of prostatitis such as chronic bacterial prostatitis and chronic pelvic pain syndrome (CPPS).
Men with this disease often have chills, fever, pain in the lower back and genital area, urinary frequency and urgency often at night, burning or painful urination, body aches, and a demonstrable infection of the urinary tract, as evidenced by white blood cells and bacteria in the urine. Acute prostatitis may be a complication of prostate biopsy.
Acute prostatitis is relatively easy to diagnose due to its symptoms that suggest infection. The organism may be found in blood or urine, and sometimes in both. Common bacteria are Escherichia coli, Klebsiella, Proteus, Pseudomonas, Enterobacter, Enterococcus, Serratia, and Staphylococcus aureus. This can be a medical emergency in some patients and hospitalization with intravenous antibiotics may be required. A complete blood count reveals increased white blood cells. Sepsis from prostatitis is very rare, but may occur in immunocompromised patients; high fever and malaise generally prompt
Coccidioidomycosis ( /kɒkˌsɪdiɔɪdoʊmaɪˈkoʊsɪs/, commonly known as "Valley fever", as well as "California fever", "Desert rheumatism", and "San Joaquin Valley fever") is a fungal disease caused by Coccidioides immitis or C. posadasii. It is endemic in certain parts of Arizona, California, Nevada, New Mexico, Texas, Utah and northwestern Mexico.
C. immitis resides in the soil in certain parts of the southwestern United States, northern Mexico, and parts of Central and South America. It is dormant during long dry spells, then develops as a mold with long filaments that break off into airborne spores when the rains come. The spores, known as arthroconidia, are swept into the air by disruption of the soil, such as during construction, farming, or an earthquake.
Infection is caused by inhalation of the particles. The disease is not transmitted from person to person. The infection ordinarily resolves leaving the patient with a specific immunity to re-infection.C. immitis is a dimorphic saprophytic organism that grows as a mycelium in the soil and produces a spherule form in the host organism.
The disease is usually mild, with flu-like symptoms and rashes. The Mayo Clinic estimates that
Human respiratory syncytial virus (RSV) is a virus that causes respiratory tract infections. It is a major cause of lower respiratory tract infections and hospital visits during infancy and childhood. A prophylactic medication (not a vaccine) exists for preterm birth (under 35 weeks gestation) infants and infants with a congenital heart defect (CHD) or bronchopulmonary dysplasia (BPD). Treatment is limited to supportive care, including oxygen therapy.
In temperate climates there is an annual epidemic during the winter months. In tropical climates, infection is most common during the rainy season.
In the United States, 60% of infants are infected during their first RSV season, and nearly all children will have been infected with the virus by 2–3 years of age. Of those infected with RSV, 2–3% will develop bronchiolitis, necessitating hospitalization. Natural infection with RSV induces protective immunity which wanes over time—possibly more so than other respiratory viral infections—and thus people can be infected multiple times. Sometimes an infant can become symptomatically infected more than once, even within a single RSV season. Severe RSV infections have increasingly been found
La Crosse encephalitis is an encephalitis caused by an arbovirus (the La Crosse virus) which has a mosquito vector (Ochlerotatus triseriatus synonym Aedes triseriatus).
La Crosse encephalitis virus (LACV) is one of a group of mosquito-transmitted viruses that can cause encephalitis, or inflammation of the brain. LAC encephalitis is rare; in the United States, about 80-100 LACV disease cases are reported each year.
The La Crosse encephalitis virus is a bunyavirus.
Most cases of LAC encephalitis occur in children under 16 years of age. LAC virus is a zoonotic pathogen cycled between the daytime-biting treehole mosquito, Aedes triseriatus, and vertebrate amplifier hosts (chipmunks, tree squirrels) in deciduous forest habitats. The virus is maintained over the winter by transovarial transmission in mosquito eggs. If the female mosquito is infected, she may lay eggs that carry the virus, and the adults coming from those eggs may be able to transmit the virus to chipmunks and to humans.
Anyone bitten by a mosquito in an area where the virus is circulating can get infected with LACV. The risk is highest for people who live, work or recreate in woodland habitats, because of greater
Laryngeal papillomatosis, also known as recurrent respiratory papillomatosis or glottal papillomatosis, is a rare medical condition (2 per 100,000 adults and 4.5 per 100,000 children), caused by a HPV infection of the throat. Laryngeal papillomatosis causes assorted tumors or papillomas to develop over a period. Without treatment it is potentially fatal as uncontrolled growths could obstruct the airway. Laryngeal papillomatosis is caused by HPV types 6 and 11, in which benign tumors form on the larynx or other areas of the respiratory tract. These tumors can recur frequently, may require repetitive surgery, and may interfere with breathing. The disease can be treated with surgery and antivirals.
In general, doctors are not sure what causes some people to contract laryngeal papillomatosis while others who have been exposed to HPV types 6 and 11 do not contract the disease. Since the disease is most commonly found in children the disease may be caused by an infant contracting HPV from the mother during vaginal child birth . There is no evidence that it is transmitted through oral sex, and it is not considered a sexually transmitted disease.
In adults the symptoms Laryngeal
Nanobacterium (NAH-no-bak-TEER-ee-əm, pl. nanobacteria NAH-no-bak-TEER-ee-uh) is the unit or member name of a proposed class of living organisms, specifically cell-walled microorganisms with a size much smaller than the generally accepted lower limit for life (about 200 nanometres for bacteria). Originally based on observed nano-scale structures in geological formations (including one meteorite), the status of nanobacteria has been controversial, with some researchers suggesting they are a new class of living organism capable of incorporating radiolabeled uridine, and others attributing to them a simpler, abiotic nature. One skeptic dubbed them "the cold fusion of microbiology", in reference to a notorious episode of supposed erroneous science. The term "calcifying nanoparticles" (CNPs) has also been used as a conservative name regarding their possible status as a life form.
Research tends to agree that these structures exist, and appear to replicate in some way. However, the idea that they are living entities has now largely been discarded, and the particles are instead believed to be nonliving crystallizations of minerals and organic molecules. In medicine, they have been
Tick-borne encephalitis (TBE) is a viral infectious disease involving the central nervous system. The disease most often manifests as meningitis, encephalitis, or meningoencephalitis. Although TBE is most commonly recognized as a neurological disorder, mild fever can also occur. Long-lasting or permanent neuropsychiatric sequelae are observed in 10-20% of infected patients.
The number of reported cases has been increasing in most countries.
The tick-borne encephalitis virus is known to infect a range of hosts including ruminants, birds, rodents, carnivores, horses and humans. The disease can also be zoonotic, with ruminants and dogs providing the principal source of infection for humans.
The virus can infect the brain (encephalitis), the meninges (meningitis) or both (meningoencephalitis). In general, mortality is 1% to 2%, with deaths occurring 5 to 7 days after the onset of neurologic signs.
In dogs, the disease also manifests as a neurological disorder with signs varying from tremors to seizures and death.
In ruminants, neurological disease is also present, and animals may refuse to eat, appear lethargic, and also develop respiratory signs.
It is transmitted by the bite of
Tinea manuum is a fungal infection of the hand. It is typically more aggressive than tinea pedis but similar in look. Itching, burning, cracking, and scaling are observable and may be transmitted sexually or otherwise, whether or not symptoms are present.
It can usually be treated with long term use of a topical antifungal cream such as selenium sulfide shampoo. However, in some cases an oral antifungal such as griseofulvin may have to be prescribed.
Trichuriasis is a parasitic infection primarily in the tissue of the cecum, appendix, colon and rectum that is caused by Trichuris trichiura (whipworm), an intestinal parasitic nematode (roundworm).
The phylum of Trichuris trichiura is Aschelminthes, while its class is Adenophorea, its order is Stichosmida, and its family is Trichocephaloidea. Its genus, Trichocephalus, was recorded as a more accurate name, however the generic name trichuris, which means “hair tail” (which implies that the posterior end of the worm is the attenuated section), remains the dominant name form used today.
Human Whipworm, Trichocephaliasis, and Tricuriasis are all synonyms for Trichuriasis, human infection of the Trichuris trichiura intestinal nematode. In Spanish, trichuriasis is called “Tricuriasis,” while in it is known as “Trichuriose” in French and “Peitschenwurmbefall” in German.
The first written record of Trichuris trichiura was made by Morgani, an Italian scientist, who identified the presence of the parasite in a case of worms residing in the colon in 1740. Exact Morphological description and figures were first recorded in 1761 by Roedere, a German physicist. Soon after morphology and visual
Tropical ulcer (also known as "Aden ulcer," "Jungle rot," "Malabar ulcer," and "Tropical phagedena") is a lesion occurring in cutaneous leishmaniasis. It is caused by a variety of microorganisms, including mycobacteria. It is common in tropical climates.
Ulcers occur on exposed parts of the body, primarily on anterolateral aspect of the lower limbs and may erode muscles and tendons, and sometimes, the bones. These lesions may frequently develop on preexisting abrasions or sores sometimes beginning from a mere scratch.
The vast majority of the tropical ulcers occur below the knee, usually around the ankle. They are often initiated by minor trauma, and subjects with poor nutrition are at higher risk. Once developed, the ulcer may become chronic and stable, but also it can run a destructive course with deep tissue invasion, osteitis, and risk of amputation. Unlike Buruli ulcer, tropical ulcers are very painful. Lesions begin with inflammatory papules that progress into vesicles and rupture with the formation of an ulcer.
There is no single agreed causative organism for tropical ulcer, although early lesions may be colonized or infected by Bacillus fusiformis (Vincent's organism),
Yersiniosis is an infectious disease caused by a bacterium of the genus Yersinia. In the United States, most yersiniosis infections among humans are caused by Y. enterocolitica. Yersiniosis is mentioned as a specific zoonotic disease to prevent outbreaks in European Council Directive 92/117/EEC.
Infection with Y. enterocolitica occurs most often in young children. The infection is thought to be contracted through the consumption of undercooked meat products, unpasteurized milk, or water contaminated by the bacteria. It has been also sometimes associated with handling raw chitterlings.
Infection with Y. enterocolitica can cause a variety of symptoms depending on the age of the person infected, therefore it's often referred to as "monkey of diseases". Common symptoms in children are fever, abdominal pain, and diarrhea, which is often bloody. Symptoms typically develop 4 to 7 days after exposure and may last 1 to 3 weeks or longer. In older children and adults, right-sided abdominal pain and fever may be the predominant symptoms, and may be confused with appendicitis. In a small proportion of cases, complications such as skin rash, joint pains, or the spread of bacteria to the
Bolivian hemorrhagic fever (BHF), also known as black typhus or Ordog Fever, is a hemorrhagic fever and zoonotic infectious disease originating in Bolivia after infection by Machupo virus.
BHF was first identified in 1959 by a research group led by Karl Johnson, an ambisense RNA virus of the Arenaviridae family. The mortality rate is estimated at 5 to 30 percent. Due to its pathogenicity, Machupo virus requires Biosafety Level Four conditions, the highest level.
In February and March 2007, some 20 suspected BHF cases (3 fatal) were reported to the El Servicio Departamental de Salud (SEDES) in Beni Department, Bolivia, and in February 2008, at least 200 suspected new cases (12 fatal) were reported to SEDES. In November 2011, a SEDES expert involved in a serosurvey to determine the extent of Machupo virus infections in the Department after the discovery of a second confirmed case near the departmental capital of Trinidad in November, 2011, expressed concern about expansion of the virus' distribution outside the endemic zone in Mamoré and Iténez provinces.
The vector is the vesper mouse Calomys callosus, a rodent indigenous to northern Bolivia. Infected animals are asymptomatic and
Cryptosporidiosis, also known as crypto, is a parasitic disease caused by Cryptosporidium, a protozoan parasite in the phylum Apicomplexa. It affects the intestines of mammals and is typically an acute short-term infection. It is spread through the fecal-oral route, often through contaminated water; the main symptom is self-limiting diarrhea in people with intact immune systems. In immunocompromised individuals, such as AIDS patients, the symptoms are particularly severe and often fatal.
Cryptosporidium is the organism most commonly isolated in HIV positive patients presenting with diarrhea. Treatment is symptomatic, with fluid rehydration, electrolyte correction and management of any pain. Despite not being identified until 1976, it is one of the most common waterborne diseases and is found worldwide. The parasite is transmitted by environmentally hardy microbial cysts (oocysts) that, once ingested, exist in the small intestine and result in an infection of intestinal epithelial tissue.
The organism was first described in 1907 by Tyzzer, who recognised it was a coccidian.
Cryptosporidium is a protozoan pathogen of the Phylum Apicomplexa and causes a diarrheal illness called
Pott's disease or Pott disease is a presentation of extrapulmonary tuberculosis that affects the spine, a kind of tuberculous arthritis of the intervertebral joints. It is named after Percivall Pott (1714–1788), a London surgeon who trained at St Bartholomew's Hospital, London. The lower thoracic and upper lumbar vertebrae are the areas of the spine most often affected. Scientifically, it is called tuberculous spondylitis and it is most commonly localized in the thoracic portion of the spine. Pott’s disease results from haematogenous spread of tuberculosis from other sites, often pulmonary. The infection then spreads from two adjacent vertebrae into the adjoining intervertebral disc space. If only one vertebra is affected, the disc is normal, but if two are involved, the disc, which is avascular, cannot receive nutrients and collapses. The disc tissue dies and is broken down by caseation, leading to vertebral narrowing and eventually to vertebral collapse and spinal damage. A dry soft tissue mass often forms and superinfection is rare.
- CBC : leukocytisis – elevated erythrocyte sedimentation rate >100 mm/h
- Tuberculin skin test (purified protein derivative [PPD]) results are
Chronic recurrent multifocal osteomyelitis (CRMO) ("multifocal" because it can erupt in different sites, primarily bones; "osteomyelitis" because it is very similar to that disease but appears to be without any infection), also known as chronic recurring multifocal osteomyelitis, is a rare condition (1:1,000,000), in which the bones have lesions, inflammation, and pain. Its definition is evolving. Many doctors and articles described CRMO as an autoimmune disease that has symptoms similar to osteomyelitis, but without the infection. Some doctors thought CRMO was related to SAPHO syndrome. Cutting edge research now classifies CRMO as an inherited autoinflammatory disease but have yet to isolate the exact gene responsible for it. Some specialists believe they have discovered a link between CRMO with a rare allele of marker D18S60, resulting in a haplotype relative risk (HRR) of 18. Other experts found that "mutations in LPIN2 cause a syndromic form of chronic recurrent multifocal osteomyelitis known as Majeed syndrome, while mutations in pstpip2 cause a murine form of the disorder. The roles played by LPIN2 and the human homolog of pstpip2, PSTPIP2, in the etiology of chronic
Colorado tick fever (CTF) (also called Mountain tick fever, American tick fever, and "American mountain tick fever") is an obtuse viral infection transmitted from the bite of an infected tick (Dermacentor andersoni). It should not be confused with the bacterial tick-borne infection, Rocky Mountain spotted fever.
The type species of the genus Coltivirus, Colorado tick fever virus (CTFV) infects haemopoietic cells, particularly erythrocytes, which explains how the virus is transmitted by ticks and also accounts for the incidence of transmission via blood transfusion.
The disease develops from March to September, with the highest infections occurring in June. The disease is found almost exclusively in the western United States and Canada, mostly in high mountain areas such as Colorado and Idaho. The CTFV was first isolated from human blood in 1944.
The virus particle, like other Coltiviruses, is ~80 nm in diameter and is generally nonenveloped. The double-stranded RNA viral genome is ~20,000bp long and is divided into 11 segments, which are termed Seg-1 to Seg-12. Viral replication in infected cells is associated with characteristic cytoplasmic granular matrices. Evidence suggests
Diphtheria (Greek διφθέρα (diphthera) "pair of leather scrolls") is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic, Gram-positive bacterium. It is characterized by sore throat, low fever, and an adherent membrane (a pseudomembrane) on the tonsils, pharynx, and/or nasal cavity. A milder form of diphtheria can be restricted to the skin. Less common consequences include myocarditis (about 20% of cases) and peripheral neuropathy (about 10% of cases).
Diphtheria is a contagious disease spread by direct physical contact or breathing the aerosolized secretions of infected individuals. Historically quite common, diphtheria has largely been eradicated in industrialized nations through widespread vaccination. In the United States, for example, there were 52 reported cases of diphtheria between 1980 and 2000; between 2000 and 2007, there were only three cases as the diphtheria–pertussis–tetanus (DPT) vaccine is recommended for all school-age children. Boosters of the vaccine are recommended for adults, since the benefits of the vaccine decrease with age without constant re-exposure; they are particularly recommended for those traveling to
Epidermodysplasia verruciformis (also called Lewandowsky-Lutz dysplasia or Lutz-Lewandowsky epidermodysplasia verruciformis) is an extremely rare autosomal recessive genetic hereditary skin disorder associated with a high risk of carcinoma of the skin. It is characterized by abnormal susceptibility to human papillomaviruses (HPVs) of the skin. The resulting uncontrolled HPV infections result in the growth of scaly macules and papules, particularly on the hands and feet. It is typically associated with HPV types 5 and 8, which are found in about 80% of the normal population as asymptomatic infections, although other types may also contribute.
The condition usually has an onset of between the ages of 1–20, but can occasionally present in middle-age. It is named after the physicians who first documented it, Felix Lewandowsky and Wilhelm Lutz.
The cause of the condition is an inactivating HP mutation in either the EVER1 or EVER2 genes, which are located adjacent to one another on chromosome 17. The precise function of these genes is not yet fully understood, but they play a role in regulating the distribution of zinc in the cell nucleus. It has been shown that zinc is a necessary
Influenza, commonly known as the flu, is an infectious disease of birds and mammals caused by RNA viruses of the family Orthomyxoviridae, the influenza viruses. The most common symptoms are chills, fever, sore throat, muscle pains, headache (often severe), coughing, weakness/fatigue and general discomfort. Although it is often confused with other influenza-like illnesses, especially the common cold, influenza is a more severe disease caused by a different type of virus. Influenza may produce nausea and vomiting, particularly in children, but these symptoms are more common in the unrelated gastroenteritis, which is sometimes inaccurately referred to as "stomach flu" or "24-hour flu".
Flu can occasionally lead to pneumonia, either direct viral pneumonia or secondary bacterial pneumonia, even for persons who are usually very healthy. In particular it is a warning sign if a child (or presumably an adult) seems to be getting better and then relapses with a high fever as this relapse may be bacterial pneumonia. Another warning sign is if the person starts to have trouble breathing. A 2009 New England Journal of Medicine article stated that it is difficult to tell bacterial from viral
Lemierre's syndrome (or Lemierre's disease, also known as postanginal sepsis and human necrobacillosis) is a form of thrombophlebitis usually caused by the bacterium Fusobacterium necrophorum, and occasionally by other members of the genus Fusobacterium (F. nucleatum, F. mortiferum and F. varium etc.) and usually affects young, healthy adults. Lemierre's syndrome develops most often after a sore throat caused by some bacterium of the Streptococcus genus has created a peritonsillar abscess, a pocket filled with pus and bacteria near the tonsils. Deep in the abscess, anaerobic bacteria (microbes that do not require oxygen) like Fusobacterium necrophorum can flourish. The bacteria penetrate from the abscess into the neighboring jugular vein in the neck and there they cause an infected clot (thrombosis) to form, from which bacteria are seeded throughout the body by the bloodstream (bacteremia). Pieces of the infected clot break off and travel to the lungs as emboli blocking branches of the pulmonary artery bringing deoxygenated blood from the heart to the lungs. This causes shortness of breath, chest pain and severe pneumonia. Fusobacteria are a normal part of the oropharyngeal flora.
Orbital cellulitis is an inflammation of eye tissues posterior to the orbital septum. It most commonly refers to an acute spread of infection into the eye socket from either the adjacent sinuses or through the blood. When it affects the rear of the eye, it is known as retro-orbital cellulitis.
It should not be confused with periorbital cellulitis, which refers to cellulitis anterior to the septum.
Patients commonly complain of pain when moving the eye, sudden loss of vision, bulging of the eye or eyes that are infected and limited eye movement. Along with these symptoms, patients typically have redness and swelling of the eyelid, pain, discharge, inability to open the eye, occasional fever and lethargy. It is usually caused by a previous sinusitis. Other causes include infection of nearby structures, trauma and previous surgery.
Orbital cellulitis occurs commonly from bacterial infection spread by the paranasal sinuses. Other ways in which orbital cellulitis may occur is from infection in the blood stream and from an eyelid skin infection. Upper respiratory infection, sinusitis, trauma to the eye, ocular or periocular infection and systemic infection all increase one’s risk of
Osteomyelitis (osteo- derived from the Greek word osteon, meaning bone, myelo- meaning marrow, and -itis meaning inflammation) simply means an infection of the bone or bone marrow. It can be usefully subclassified on the basis of the causative organism (pyogenic bacteria or mycobacteria), the route, duration and anatomic location of the infection.
In general, microorganisms may infect bone through one or more of three basic methods: via the bloodstream, contiguously from local areas of infection (as in cellulitis), or penetrating trauma, including iatrogenic causes such as joint replacements or internal fixation of fractures or root-filled teeth. Once the bone is infected, leukocytes enter the infected area, and, in their attempt to engulf the infectious organisms, release enzymes that lyse the bone. Pus spreads into the bone's blood vessels, impairing their flow, and areas of devitalized infected bone, known as sequestra, form the basis of a chronic infection. Often, the body will try to create new bone around the area of necrosis. The resulting new bone is often called an involucrum. On histologic examination, these areas of necrotic bone are the basis for distinguishing between
Septicemic (or septicaemic) plague is a deadly blood infection, one of the three main forms of plague. It is caused by Yersinia pestis, a gram-negative bacterium.
Like some other forms of gram-negative sepsis, septicemic plague can cause disseminated intravascular coagulation, and is almost always fatal without treatment (the mortality rate in medieval times was 99-100 percent). Septicemic plague is the rarest of the three plague varieties; the other forms are bubonic and pneumonic plague.
The disease is contracted primarily through the bite of an infected rodent or insect, but like bubonic plague can very rarely be contracted through an opening in the skin or by cough from another infected human. After initial infection, the bacteria multiply in the blood, causing bacteremia and severe sepsis. In septicemic plague, bacterial endotoxins cause disseminated intravascular coagulation (DIC), where tiny blood clots form throughout the body, possibly resulting in ischemic necrosis (tissue death due to lack of circulation/perfusion to that tissue).
DIC results in depletion of the body's clotting resources, so that it can no longer control bleeding. Consequently, there is bleeding into the
The Buruli ulcer (also known as the Bairnsdale ulcer or Searls ulcer) is an infectious disease caused by Mycobacterium ulcerans. The genus also includes the causative agents of tuberculosis and leprosy (M. tuberculosis and M. leprae, respectively). The early stage of infection is characterised by a painless nodule, with non-pyogenic, necrotising lesions developing in the skin, and occasionally in adjacent bone, as the disease progresses. M. ulcerans secretes a lipid toxin, mycolactone, which functions as an immune suppressant, necrotising agent and activator of cellular apoptosis in mammalian tissues.
James Augustus Grant, in his book A Walk across Africa (1864), describes how his leg became grossly swollen and stiff with later a copious discharge. This was almost certainly the severe oedematous form of the disease, and is the first known description of the infection. Buruli ulcer disease was identified in 1897 by Sir Albert Cook, a British physician, at Mengo Hospital in Kampala, Uganda. A detailed description of the disease was written in 1948 by Professor Peter MacCallum and his colleagues, who were treating patients from the Bairnsdale district, near Melbourne, Australia. They
Chancroid (also known as soft chancre and "ulcus molle") is a bacterial sexually transmitted infection characterized by painful sores on the genitalia. Chancroid is known to spread from one individual to another solely through sexual contact.
After an incubation period of one day to two weeks, chancroid begins with a small bump that becomes an ulcer within a day of its appearance. The ulcer characteristically:
In more specific terms, the CDC's standard clinical definition for a probable case of chancroid includes all of the following:
About half of infected men have only a single ulcer. Women frequently have four or more ulcers, with fewer symptoms. The ulcers appear in specific locations, such as the coronal sulcus of the uncircumcised glans penis in men, or the fourchette and labia minora in women.
In women, the most common location for ulcers is the labia majora. "Kissing ulcers" may develop. These are ulcers that occur on opposing surfaces of the labia. Other areas such as the labia minora, perineal area, and inner thighs may also be involved. The most common symptoms in women are dysuria (pain with urination) and dyspareunia (pain with intercourse).
The initial ulcer may be
Herpes simplex (Greek: ἕρπης herpēs, "creeping" or "latent") is a viral disease from the herpesviridae family caused by both Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2). Infection with the herpes virus is categorized into one of several distinct disorders based on the site of infection. Oral herpes, the visible symptoms of which are colloquially called cold sores or fever blisters, is an infection of the face or mouth. Oral herpes is the most common form of infection. Genital herpes, known simply as herpes, is the second most common form of herpes. Other disorders such as herpetic whitlow, herpes gladiatorum, ocular herpes, cerebral herpes infection encephalitis, Mollaret's meningitis, neonatal herpes, and possibly Bell's palsy are all caused by herpes simplex viruses.
Herpes viruses cycle between periods of active disease—presenting as blisters containing infectious virus particles—that last 2–21 days, followed by a remission period. Genital herpes, however, is often asymptomatic, though viral shedding may still occur. After initial infection, the viruses are transported along sensory nerves to the sensory nerve cell bodies, where they become latent and reside lifelong.
Lyme disease, Lyme borreliosis is an emerging infectious disease caused by at least three species of bacteria belonging to the genus Borrelia. Borrelia burgdorferi sensu stricto is the main cause of Lyme disease in North America, whereas Borrelia afzelii and Borrelia garinii cause most European cases. The disease is named after the town of Old Lyme, Connecticut, USA, where a number of cases were identified in 1975. Although Allen Steere realized that Lyme disease was a tick-borne disease in 1978, the cause of the disease remained a mystery until 1981, when B. burgdorferi was identified by Willy Burgdorfer.
Lyme disease is the most common tick-borne disease in the Northern Hemisphere. Borrelia is transmitted to humans by the bite of infected ticks belonging to a few species of the genus Ixodes ("hard ticks"). Early symptoms may include fever, headache, fatigue, depression, and a characteristic circular skin rash called erythema migrans (EM). Left untreated, later symptoms may involve the joints, heart, and central nervous system. In most cases, the infection and its symptoms are eliminated by antibiotics, especially if the illness is treated early. Delayed or inadequate treatment
Multi-drug-resistant tuberculosis (MDR-TB) is defined as tuberculosis that is resistant to at least isoniazid (INH) and rifampicin (RMP), the two most powerful first-line treatment anti-TB drugs. Isolates that are multiply resistant to any other combination of anti-TB drugs but not to INH and RMP are not classed as MDR-TB.
MDR-TB develops during treatment of fully sensitive TB when the course of antibiotics is interrupted and the levels of drug in the body are insufficient to kill 100% of bacteria. This can happen for a number of reasons: Patients may feel better and halt their antibiotic course, drug supplies may run out or become scarce, or patients may forget to take their medication from time to time. MDR-TB is spread from person to person as readily as drug-sensitive TB and in the same manner.
MDR-TB most commonly develops in the course of TB treatment, and is most commonly due to doctors giving inappropriate treatment, or patients missing doses or failing to complete their treatment. MDR-TB strains are often less fit and less transmissible, and outbreaks occur more readily in people with weakened immune systems (e.g., patients with HIV). Outbreaks among non immunocompromised
Periorbital cellulitis, also known as preseptal cellulitis (and not to be confused with orbital cellulitis, which is behind the septum), is an inflammation and infection of the eyelid and portions of skin around the eye, anterior to the orbital septum. It may be caused by breaks in the skin around the eye, and subsequent spread to the eyelid; infection of the sinuses around the nose (sinusitis); or from spread of an infection elsewhere through the blood.
Periorbital cellulitis must be differentiated from orbital cellulitis, which is an emergency and requires intravenous (IV) antibiotics. In contrast to orbital cellulitis, patients with periorbital cellulitis do not have bulging of the eye (proptosis), limited eye movement (ophthalmoplegia), pain on eye movement, or loss of vision. If any of these features is present, one must assume that the patient has orbital cellulitis and begin treatment with IV antibiotics. CT scan may be done to delineate the extension of the infection.
It can be caused by sleeping overnight with make-up on the eyes. This can lead to microscopic pieces of make-up in the eyelid for days causing infection.
Affected individuals may experience the following;
Relapsing fever is an infection caused by certain bacteria in the genus Borrelia. It is a vector-borne disease transmitted through the bites of lice or soft-bodied ticks.
Along with Rickettsia prowazekii and Bartonella quintana, Borrelia recurrentis is one of three pathogens of which the body louse (Pediculus humanus humanus) is a vector. Louse-borne relapsing fever is more severe than the tick-borne variety.
Louse-borne relapsing fever occurs in epidemics amid poor living conditions, famine and war in the developing world. It is currently prevalent in Ethiopia and Sudan.
Mortality rate is 1% with treatment and 30-70% without treatment. Poor prognostic signs include severe jaundice, severe change in mental status, severe bleeding and a prolonged QT interval on ECG.
Lice that feed on infected humans acquire the Borrelia organisms that then multiply in the gut of the louse. When an infected louse feeds on an uninfected human, the organism gains access when the victim crushes the louse or scratches the area where the louse is feeding. B. recurrentis infects the person via mucous membranes and then invades the bloodstream. No animal reservoir exists.
Tick-borne relapsing fever is found
Sodoku is a bacterial zoonotic disease. It is caused by outnumbered spirochaete Spirillum minus. It is a form of rat-bite fever (RBF).
The infections are acquired through rat bites or scratches. It can occur as nosocomial infections (i.e., acquired from hospitals), or due to exposure or close associations with animals preying on rats, mice, squirrels etc. Sodoku is mostly seen in Asia. The incubation period is 4 to 28 days.
The initial scratch or wound caused by a bite from a carrier rodent will result in mild inflammatory reactions and ulcerations. The wounds may heal initially, but reappear with the onset of symptoms. The symptoms include recurring fever, with body temperature 101–104 °F (38–40°C). The fever lasts for 2–4 days but recur generally at 4–8 weeks. This cycle may continue for months or years together. The other symptoms include regional lymphadenitis, malaise and headache. The complications include myocarditis, endocarditis, hepatitis, splenomegaly and meningitis.
Mortality ranges from 6-10%.
Tropical spastic paraparesis (TSP), also known as HTLV-associated myelopathy or chronic progressive myelopathy, is an infection of the spinal cord by Human T-lymphotropic virus resulting in paraparesis, weakness of the legs. As the name suggests, it is most common in tropical regions, including the Caribbean and Africa.
For several decades, the term tropical spastic paraparesis was used to describe a chronic and progressive clinical syndrome that affected adults living in equatorial areas of the world. This condition was initially thought to be associated with infectious agents (such as Treponema pertenue and Treponema pallidum, which cause inflammation of the central nervous system) and with chronic nutritional deficiencies (such as avitaminosis) or exposure to potentially toxic foods (such as bitter cassava). Neurological and modern neuroepidemiological studies found that in some individuals no single cause could explain the progressive weakness, sensory disturbance, and sphincter dysfunction that affected individuals with TSP. In spite of public health programs created to eradicate the above-mentioned infectious and nutritional conditions in the tropics, large numbers of people
Extensively drug-resistant tuberculosis (XDR-TB) is a form of tuberculosis caused by bacteria that are resistant to some of the most effective anti-TB drugs. XDR-TB strains have arisen after the mismanagement of individuals with multidrug-resistant TB (MDR-TB).
One in three people in the world is infected with TB bacteria. Only when the bacteria become active do people become ill with TB. Bacteria become active as a result of anything that can reduce the person’s immunity, such as HIV, advancing age, or some medical conditions. TB can usually be treated with a course of four standard, or first-line, anti-TB drugs. If these drugs are misused or mismanaged, multidrug-resistant TB (MDR-TB) can develop. MDR-TB takes longer to treat with second-line drugs, which are more expensive and have more side-effects. XDR-TB can develop when these second-line drugs are also misused or mismanaged and therefore also become ineffective.
XDR-TB raises concerns of a future TB epidemic with restricted treatment options, and jeopardizes the major gains made in TB control and progress on reducing TB deaths among people living with HIV/AIDS. It is therefore vital that TB control be managed properly and
Histoplasmosis (also known as "Cave disease," "Darling's disease," "Ohio valley disease," "Reticuloendotheliosis," "Spelunker’s Lung" and Caver's disease) is a disease caused by the fungus Histoplasma capsulatum. Symptoms of this infection vary greatly, but the disease primarily affects the lungs. Occasionally, other organs are affected; this is called disseminated histoplasmosis, and it can be fatal if left untreated. Histoplasmosis is common among AIDS patients because of their suppressed immune system. Histoplasmosis is generally contracted from contact to microscopic bacteria borne from decomposing biological fluids, most notably human excretions like urine, vomit, and feces. Cases of histoplasmosis have declined acutely since the Industrial Revolution as quality of life improved dramatically and humans were no longer living in their own squalor. Unfortunately, it is still a major killer in third world countries and can be contracted easily in the first world by living among the aforementioned human fluids.
If symptoms of histoplasmosis infection occur, they will start within 3 to 17 days after exposure; the average is 12–14 days. Most affected individuals have clinically
Leishmaniasis is a disease caused by protozoan parasites that belong to the genus Leishmania and is transmitted by the bite of certain species of sand fly (subfamily Phlebotominae). Although the majority of the literature mentions only one genus transmitting Leishmania to humans (Lutzomyia) in America, a 2003 study by Galati suggested a new classification for American sand flies, elevating several subgenera to the genus level. Elsewhere in the world, the genus Phlebotomus is considered the vector of leishmaniasis.
Most forms of the disease are transmissible only from animals (zoonosis), but some can be spread between humans. Human infection is caused by about 21 of 30 species that infect mammals. These include the L. donovani complex with three species (L. donovani, L. infantum, and L. chagasi); the L. mexicana complex with four main species (L. mexicana, L. amazonensis, and L. venezuelensis); L. tropica; L. major; L. aethiopica; and the subgenus Viannia with four main species (L. (V.) braziliensis, L. (V.) guyanensis, L. (V.) panamensis, and L. (V.) peruviana). The different species are morphologically indistinguishable, but they can be differentiated by isoenzyme analysis, DNA
An overwhelming post-splenectomy infection (OPSI) is a rare but rapidly fatal infection occurring in individuals following removal of the spleen. The infections are typically characterized by either meningitis or sepsis, and are caused by encapsulated organisms including Streptococcus pneumoniae.
The risk of OPSI is 0.23–0.42 percent per year, with a lifetime risk of 5 percent. Most infections occur in the first few years following splenectomy, but the risk of OPSI is lifelong. OPSI is nearly uniformly fatal without treatment, and modern treatment has decreased the mortality to approximately 40–70 percent. Individuals with OPSI are most commonly treated with antibiotics and supportive care. Measures to prevent OPSI include vaccination and prophylactic antibiotics.
The spleen contains many macrophages (part of the reticuloendothelial system), which are immune cells that phagocytose (eat) and destroy bacteria. In particular, these macrophages are activated when bacteria are bound by IgG antibodies (IgG1 or IgG3) or the complement component C3b. These types of antibodies and complements are immune substances called opsonizers, molecules that bind to the surface of bacteria to
Pertussis — commonly called whooping cough ( /ˈhuːpɪŋ kɒf/ or /ˈhwuːpɪŋ kɒf/) — is a highly contagious bacterial disease caused by Bordetella pertussis. In some countries, this disease is called the 100 days' cough or cough of 100 days.
Symptoms are initially mild, and then develop into severe coughing fits, which produce the namesake high-pitched "whoop" sound in infected babies and children when they inhale air after coughing. The coughing stage lasts approximately six weeks before subsiding.
Prevention by vaccination is of primary importance because treatment is of little benefit to the person infected. However, antibiotics shorten the duration of infectiousness and are thus recommended. It is estimated that the disease currently affects 48.5 million people yearly, resulting in nearly 295,000 deaths.
The classic signs of pertussis are a paroxysmal cough, inspiratory whoop, and vomiting after coughing. The cough from pertussis has been documented to cause subconjunctival hemorrhages, rib fractures, urinary incontinence, hernias, post-cough fainting, and vertebral artery dissection. If there is vomiting after a coughing spell or an inspiratory whooping sound on coughing, the
Annual ryegrass toxicity (ARGT) is the poisoning of livestock from toxin contained in bacterially infected annual ryegrass. The toxin is produced by the bacterium Rathayibacter toxicus (formerly Clavibacter toxicus), which is carried into the ryegrass by the nematode Anguina funesta.
ARGT was first recorded in vicinity of Black Springs, South Australia, in the 1950s and then near Gnowangerup, Western Australia, in the 1960s. The disease has spread rapidly and approximately 40,000 to 60,000 square kilometres of farmland in Western Australia, and similar areas in South Australia are now infested by the ARGT-causing organisms. Most ARGT-related livestock losses occur during October to January, but losses have been recorded as late as April.
Herbicide applications aimed to reduce ryegrass population have been successful in reducing the risk of ARGT but have undesirable effects such as rapid reduction in pasture productivity and increase in ryegrass herbicide resistance.
A recently released biological control agent, the twist fungus, has been demonstrated to be effective in reducing the risk ARGT without the need of controlling ryegrass. The first use of the twist fungus inoculum was in
Blastomycosis (also known as "North American blastomycosis," "Blastomycetic dermatitis," and "Gilchrist's disease") is a fungal infection caused by the organism Blastomyces dermatitidis. Endemic to portions of North America, blastomycosis causes clinical symptoms similar to histoplasmosis.
Blastomycosis can present in one of the following ways:
Infection occurs by inhalation of the fungus from its natural soil habitat. Once inhaled in the lungs, they multiply and may disseminate through the blood and lymphatics to other organs, including the skin, bone, genitourinary tract, and brain. The incubation period is 30 to 100 days, although infection can be asymptomatic.
Once suspected, the diagnosis of blastomycosis can usually be confirmed by demonstration of the characteristic broad based budding organisms in sputum or tissues by KOH prep, cytology, or histology. Tissue biopsy of skin or other organs may be required in order to diagnose extra-pulmonary disease. Blastomycosis is histologically associated with granulomatous nodules. Commercially available urine antigen testing appears to be quite sensitive in suggesting the diagnosis in cases where the organism is not readily detected.
Dental caries, also known as tooth decay or a cavity, is an infection, bacterial in origin, that causes demineralization and destruction of the hard tissues (enamel, dentin and cementum), usually by production of acid by bacterial fermentation of the food debris accumulated on the tooth surface. If demineralization exceeds saliva and other remineralization factors such as from calcium and fluoridated toothpastes, these hard tissues progressively break down, producing dental caries (cavities, holes in the teeth). The bacteria most responsible for dental cavities are the mutans streptococci, most prominently Streptococcus mutans and Streptococcus sobrinus, and lactobacilli. If left untreated, the disease can lead to pain, tooth loss and infection. Today, caries remain one of the most common diseases throughout the world. Cariology is the study of dental caries.
The presentation of caries is highly variable. However the risk factors and stages of development are similar. Initially it may appear as a small chalky area (smooth surface caries), which may eventually develop into a large cavitation. Sometimes caries may be directly visible. However other methods of detection such as X-rays
A pinworm infection or enterobiasis is a human parasitic disease and one of the most common childhood parasitic worm infections in the developed world. It is caused by infestation with the parasitic roundworm Enterobius vermicularis, commonly called the human pinworm. Infection usually occurs through the ingestion of pinworm eggs, either through contaminated hands, food, or less commonly, water. The chief symptom is itching in the anal area. The incubation time from ingestion of eggs to the first appearance of new eggs around the anus is 4 to 6 weeks. Pinworms are usually considered a nuisance rather than a serious disease. Treatment is straightforward in uncomplicated cases, however, elimination of the parasite from a family group or institution often poses significant problems—either due to an incomplete cure or reinfection. Pinworm infection has no association with any socioeconomic level, race or culture.
One third of individuals with pinworm infection are totally asymptomatic. The main symptoms are pruritus ani and perineal pruritus, i.e., itching in and around the anus and around the perineum. The itching occurs mainly during the night, and is caused by the female pinworms
Legionellosis is a potentially fatal infectious disease caused by gram negative, aerobic bacteria belonging to the genus Legionella. Over 90% of legionellosis cases are caused by Legionella pneumophila, a ubiquitous aquatic organism that thrives in temperatures between 25 and 45 °C (77 and 113 °F), with an optimum temperature of 35 °C (95 °F).
Legionellosis takes two distinct forms:
Legionnaires' disease acquired its name in July 1976 when an outbreak of pneumonia occurred among people attending a convention of the American Legion at the Bellevue-Stratford Hotel in Philadelphia. On January 18, 1977 the causative agent was identified as a previously unknown strain of bacteria, subsequently named Legionella. Some people can be infected with the Legionella bacteria and have only mild symptoms or no illness at all.
Outbreaks of Legionnaires' disease receive significant media attention. However, this disease usually occurs as single, isolated cases not associated with any recognized outbreak. When outbreaks do occur, they are usually in the summer and early autumn, though cases may occur at any time of year. Most infections occur in those who are middle-age or older.
Pogosta disease is a viral disease, established to be identical with other diseases, Karelian fever and Ockelbo disease. The names are derived from the words Pogosta, Karelia and Ockelbo, respectively.
It has long been suspected that the disease is caused by a Sindbis-like virus, a positive-stranded RNA virus belonging to the Alphavirus genus and family Togaviridae. In 2002 a strain of Sindbis was isolated from patients during an outbreak of the Pogosta disease in Finland, confirming the hypothesis.
This disease is mainly found in the Eastern parts of Finland; a typical Pogosta disease patient is a middle-aged person who has been infected through a mosquito bite while picking berries in the autumn. The prevalence of the disease is about 100 diagnosed cases every year, with larger outbreaks occurring in 7-year intervals.
The symptoms of the disease include usually rash, as well as mild fever and other flu-like symptoms; in most cases the symptoms last less than 5 days. However, in some cases, the patients develop a painful arthritis. There are no known chemical agents available to treat the disease.
Yersinia pestis (formerly Pasteurella pestis) is a Gram-negative rod-shaped bacterium. It is a facultative anaerobe that can infect humans and other animals.
Human Y. pestis infection takes three main forms: pneumonic, septicemic, and the notorious bubonic plagues. All three forms are widely believed to have been responsible for a number of high-mortality epidemics throughout human history, including the Plague of Justinian in 542 and the Black Death that accounted for the death of at least one-third of the European population between 1347 and 1353. It has now been shown conclusively that these plagues originated in rodent populations in China. More recently, Y. pestis has gained attention as a possible biological warfare agent and the CDC has classified it as a category A pathogen requiring preparation for a possible terrorist attack.
Y. pestis was discovered in 1894 by Alexandre Yersin, a Swiss/French physician and bacteriologist from the Pasteur Institute, during an epidemic of plague in Hong Kong. Yersin was a member of the Pasteur school of thought. Kitasato Shibasaburō, a German-trained Japanese bacteriologist who practiced Koch's methodology, was also engaged at the time in
Dengue fever (UK /ˈdɛŋɡeɪ/ or US /ˈdɛŋɡiː/), also known as breakbone fever, is an infectious tropical disease caused by the dengue virus. Symptoms include fever, headache, muscle and joint pains, and a characteristic skin rash that is similar to measles. In a small proportion of cases the disease develops into the life-threatening dengue hemorrhagic fever, resulting in bleeding, low levels of blood platelets and blood plasma leakage, or into dengue shock syndrome, where dangerously low blood pressure occurs.
Dengue is transmitted by several species of mosquito within the genus Aedes, principally A. aegypti. The virus has four different types; infection with one type usually gives lifelong immunity to that type, but only short-term immunity to the others. Subsequent infection with a different type increases the risk of severe complications. As there is no vaccine, prevention is sought by reducing the habitat and the number of mosquitoes and limiting exposure to bites.
Treatment of acute dengue is supportive, using either oral or intravenous rehydration for mild or moderate disease, and intravenous fluids and blood transfusion for more severe cases. The incidence of dengue fever has
Filariasis (philariasis) is a parasitic disease (usually an infectious tropical disease) that is caused by thread-like nematodes (roundworms) belonging to the superfamily Filarioidea, also known as "filariae". These are transmitted from host to host by blood-feeding arthropods, mainly black flies and mosquitoes.
Eight known filarial nematodes use humans as their definitive hosts. These are divided into three groups according to the niche within the body they occupy: 'lymphatic filariasis', 'subcutaneous filariasis', and 'serous cavity filariasis'.
The adult worms, which usually stay in one tissue, release early larvae forms known as microfilariae into the host's bloodstream. These circulating microfilariae can be taken up with a blood meal by the arthropod vector; in the vector they develop into infective larvae that can be transmitted to a new host.
Individuals infected by filarial worms may be described as either "microfilaraemic" or "amicrofilaraemic", depending on whether or not microfilaria can be found in their peripheral blood. Filariasis is diagnosed in microfilaraemic cases primarily through direct observation of microfilaria in the peripheral blood. Occult filariasis is
Pneumonic plague, a severe type of lung infection, is one of three main forms of plague, all of which are caused by the bacterium Yersinia pestis. It is more virulent and rare than bubonic plague. The difference between the versions of plague is simply the location of the infection in the body; the bubonic plague is an infection of the lymphatic system, the pneumonic plague is an infection of the respiratory system, and the septicemic plague is an infection in the blood stream.
Typically, pneumonic form is due to a spread from infection of an initial bubonic form. Primary pneumonic plague results from inhalation of fine infective droplets and can be transmitted from human to human without involvement of fleas or animals. Untreated pneumonic plague has a very high fatality rate.
Since 2002, the World Health Organization (WHO) has reported seven plague outbreaks, though some may go unreported because they often happen in remote areas. Between 1998 and 2009, nearly 24,000 cases have been reported, including about 2,000 deaths, in Africa, Asia, the Americas and Eastern Europe. 98 percent of the world's cases occur in Africa. May cause AIDS.
Pneumonic plague can be caused in two ways:
The Sin Nombre virus (in Spanish, "the nameless virus") (SNV) is the prototypical etiologic agent of hantavirus cardiopulmonary syndrome (HCPS).
Its original name was "Four Corners virus" or "Navajo Flu", but the name was changed after local residents raised objections.
It was first isolated from rodents collected near the home of one of the initial patients with hantavirus pulmonary syndrome (HPS) in the Four Corners region of the western United States. Isolation was achieved through blind passage in Peromyscus maniculatus (deer mouse) and subsequent adaptation to growth in Vero E6 cells. Additional viral strains have also been isolated from P. maniculatus associated with a fatal case in California and P. leucopus from the vicinity of probable infection of a New York case. Black Creek Canal virus was isolated from S. hispidus collected near the residence of a human case in Dade County, Florida. Another etiologic agent of HCPS, Bayou virus, was first isolated from the vicinity of Monroe, Louisiana.
SNV occurs wherever its reservoir rodent carrier, (the deer mouse Peromyscus maniculatus) is found, which includes essentially the entire United States except for the far southeastern
Bartonellosis is an infectious disease produced by bacteria of the genus Bartonella. Bartonella cause diseases such as Carrión´s disease, trench fever, cat-scratch disease, bacillary angiomatosis, peliosis hepatis, chronic bacteremia, endocarditis, chronic lymphadenopathy, and neurological disorders.
The disease was named after medical student Daniel Alcides Carrión from Cerro de Pasco, Peru. Carrión described the disease after being inoculated at his request by Doctor Evaristo M. Chávez, a close friend and coworker in Dos de Mayo National Hospital. Carrión kept a meticulous clinical history until the disease rendered him incapable of the task. Carrión proved that "Oroya fever" and "Verruga Peruana" were two stages of the same disease, not two different diseases as was thought at the time.
Carrión was inoculated with the pus of the purple lesion from a patient (Carmen Paredes) in 1885. He developed the disease three weeks after the inoculation and died several weeks later. Bartonella bacilliformis is considered the most deadly bartonella to date, with a death rate of up to 90% during the acute phase. His sacrifice demonstrated the connection between the two phases of the disease.
Ehrlichiosis is a tickborne bacterial infection, caused by bacteria of the family Anaplasmataceae, genera Ehrlichia and Anaplasma. These obligate intracellular bacteria infect and kill white blood cells.
The average reported annual incidence is 0.7 cases per million population.
Five (see note below) species have been shown to cause human infection:
The latter two infections are not well studied.
Note: In 2008, human infection by Panola Mountain (Georgia, USA) Ehrlichia species was reported. On August 3, 2011, infection by a yet-unnamed bacterium in the genus Ehrlichia carried by deer ticks that has caused flu-like symptoms in at least 25 people in Minnesota and Wisconsin was reported; human ehrlichiosis was thought to be very rare or absent in Minnesota and Wisconsin. The new species, which is very similar genetically to an Ehrlichia species found in Eastern Europe and Japan called E. muris, was identified at Mayo Clinic Health System's Eau Claire hospital.
Ehrlichia are transported between cells through the host cell filopodia during initial stages of infection, whereas, in the final stages of infection the pathogen ruptures the host cell membrane.
The most common symptoms include
Human papillomavirus (HPV) is a virus from the papillomavirus family that is capable of infecting humans. Like all papillomaviruses, HPVs establish productive infections only in keratinocytes of the skin or mucous membranes. While the majority of the known types of HPV cause no symptoms in most people, some types can cause warts (verrucae), while others can – in a minority of cases – lead to cancers of the cervix, vulva, vagina, penis, oropharynx and anus. Recently, HPV has been linked with an increased risk of cardiovascular disease. In addition, HPV 16 and 18 infections are strongly associated with an increased odds ratio of developing oropharyngeal (throat) cancer.
More than 30 to 40 types of HPV are typically transmitted through sexual contact and infect the anogenital region. Some sexually transmitted HPV types may cause genital warts. Persistent infection with "high-risk" HPV types — different from the ones that cause skin warts — may progress to precancerous lesions and invasive cancer. HPV infection is a cause of nearly all cases of cervical cancer. However, most infections with these types do not cause disease.
Most HPV infections in young females are temporary and have
Exanthema subitum (meaning sudden rash), also referred to as roseola infantum (or rose rash of infants), sixth disease (as the sixth rash-causing childhood disease), and (confusingly) baby measles, or three-day fever, is a disease of children, generally under two years old, although it has been known to occur in eighteen year olds, whose manifestations are usually limited to a transient rash ("exanthem") that occurs following a fever of about three day's duration.
It is frequently called roseola, although this term could be applied to any rose-colored rash.
It is caused by two human herpesviruses, HHV-6 (Human herpesvirus 6) and HHV-7, which are sometimes referred to collectively as Roseolovirus. There are two variants of HHV-6 (HHV-6a and HHV-6b) and studies in the US, Europe, Dubai and Japan have shown that exanthema subitum is caused by HHV-6b. This form of HHV-6 infects over 90% of infants by age 2. Research has shown that babies can be congenitally infected with HHV-6 via vertical transmission. This has been shown to occur in 1% of births in the United States.
Typically the disease affects a child between six months and two years of age, and begins with a sudden high fever
Smallpox was an infectious disease unique to humans, caused by either of two virus variants, Variola major and Variola minor. The disease is also known by the Latin names Variola or Variola vera, which is a derivative of the Latin varius, meaning "spotted", or varus, meaning "pimple". The term "smallpox" was first used in Britain in the 15th century to distinguish variola from the "great pox" (syphilis). The last naturally occurring case of smallpox (Variola minor) was diagnosed on 26 October 1977.
Smallpox localizes in small blood vessels of the skin and in the mouth and throat. In the skin it results in a characteristic maculopapular rash and, later, raised fluid-filled blisters. V. major produces a more serious disease and has an overall mortality rate of 30–35%. V. minor causes a milder form of disease (also known as alastrim, cottonpox, milkpox, whitepox, and Cuban itch) which kills about 1% of its victims. Long-term complications of V. major infection include characteristic scars, commonly on the face, which occur in 65–85% of survivors. Blindness resulting from corneal ulceration and scarring, and limb deformities due to arthritis and osteomyelitis are less common
Trichinosis, also called trichinellosis, or trichiniasis, is a parasitic disease caused by eating raw or undercooked pork or wild game infected with the larvae of a species of roundworm Trichinella spiralis, commonly called the trichina worm. There are eight Trichinella species; five are encapsulated and three are not. Only three Trichinella species are known to cause trichinosis: T. spiralis, T. nativa, and T. britovi.
Between 2002-2007, 11 cases were reported to CDC each year on average in the United States which were mostly the result of eating undercooked game, bear meat, or home-reared pigs. It is common in developing countries where meat fed to pigs is raw or undercooked, but many cases also come from developed countries in Europe and North America, where raw or undercooked pork and wild game may be consumed as delicacies.
The disease-causing agents include the eight species of Trichinella, but T. spiralis is the most important to humans due to its worldwide distribution and high pathogenicity.
The circumstances surrounding the first observation and identification of Trichinella spiralis are controversial due to a lack of medical records. In 1835, James Paget, a first-year
Paratyphoid fevers are a group of enteric illnesses caused by serotypic strains of the Salmonella genus of bacteria, S. Paratyphi.
There are three serovars of the species of S. enterica that cause paratyphoid: S. Paratyphi A, S. Paratyphi B (S. schottmuelleri and S. pullorum), and S. Paratyphi C (S. hirschfeldii).
They are transmitted by means of contaminated water or food.
The paratyphoid bears similarities with typhoid fever, and the two are referred to by the common name enteric fever. The course of paratyphoid is more benign.
Factors outside the household like unclean food from street vendors and flooding help distribute the disease from person to person. Because of poverty and poor hygiene and sanitary conditions the disease is more common in less-industrialized countries, principally owing to the problem of unsafe drinking-water, inadequate sewage disposal and flooding. Occasionally causing epidemics, paratyphoid fever is found in large parts of Asia, Africa, Central and South America. Many of those infected get the disease in Asian countries. There are about 16 million cases a year, which result in about 25,000 deaths worldwide.
Salmonella Typhi can specifically only attack
Adenovirus serotype 14 (Ad14) is a serovar of adenovirus which, unlike other adenovirus serovars, is known to cause potentially fatal adenovirus infections. According to the United States Centers for Disease Control and Prevention (CDC), as of September 2007, outbreaks have been identified in four states with ten identified deaths since May 2006.
Ad14 is a rare emerging virus that can cause severe respiratory infection, which can sometimes be fatal, even in healthy young adults. Ad14 isolates from all four states where outbreaks occurred were identical, based on DNA sequencing. However, the isolates were distinct from the 1955 Ad14 reference strain. This suggests that a new Ad14 variant is emerging and spreading in the United States.
At least 140 illnesses have been caused by Ad14 in New York, Oregon, Washington, and Texas. Of these patients, 53 were hospitalized, 24 of whom were admitted to intensive-care units. In all reported cases, the isolated Ad14 strain was found to be genetically identical.
The first death was that of a 12-day-old girl, born full-term and healthy, in New York in May 2006. Ad14 was isolated from postmortem swabs. No connection has been made between this case
Bacterial pneumonia is a type of pneumonia caused by bacterial infection.
Streptococcus pneumoniae (J13) is the most common bacterial cause of pneumonia in all age groups except newborn infants. Streptococcus pneumoniae is a Gram-positive bacterium that often lives in the throat of people who do not have pneumonia.
Other important Gram-positive causes of pneumonia are Staphylococcus aureus (J15.2) and Bacillus anthracis.
Gram-negative bacteria are seen less frequently: Haemophilus influenzae (J14), Klebsiella pneumoniae (J15.0), Escherichia coli (J15.5), Pseudomonas aeruginosa (J15.1), and Moraxella catarrhalis are the most common.
These bacteria often live in the gut and enter the lungs when contents of the gut (such as vomit or faeces) are inhaled.
"Atypical" bacteria are Coxiella burnetii, Chlamydophila pneumoniae (J16.0), Mycoplasma pneumoniae (J15.7), and Legionella pneumophila.
Many people falsely believe they are called "atypical" because they are uncommon and/or do not respond to common antibiotics and/or cause atypical symptoms. In reality, they are "atypical" because they do not gram stain as well as gram-negative and gram-positive organisms.
Pneumonia caused by Yersinia
Bovine virus diarrhea or bovine viral diarrhea (BVD)or bovine viral diarrhoea (UK English) is a disease of cattle which reduces productivity and increases death loss. It is caused by a Pestivirus from the family Flaviviridae. Classical swine fever (CSF) is also caused by a pestivirus. CSF and BVD are notifiable diseases and eradication programs are administered in many countries worldwide.
The molecular biology of pestiviruses shares many similarities and peculiarities with the human hepaciviruses. Pestiviruses have the ability to establish persistent infection during pregnancy. Persistent infection with pestiviruses often goes unnoticed; for BVDV frequently nonhomologous RNA recombination events lead to the appearance of genetically distinct viruses that are lethal to the host.
There are two recognised genotypes - genotype 1 and genotype 2. These have been subdivided into subtypes: a-p for BVDV-1 and a-c for BVDV-2.
Clinical signs depend on the timing of infection and status of the animal:
If infection is acquired by a cow between 50 and 100 days of gestation, abortion is likely to occur.
Another possible outcome of infection before 120 days of gestation is the production of
Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) of mule deer, whitetailed deer, elk (or "wapiti"), and moose ("elk" in Europe). TSEs are caused by unusual infectious agents known as prions. To date, CWD has been found mainly in cervids (members of the deer family). First recognized as a clinical "wasting" syndrome in 1967 in mule deer in a wildlife research facility in northern Colorado, USA, it was identified as a TSE in 1978 and has spread to a dozen states and two Canadian provinces. CWD is typified by chronic weight loss leading to death. There is no known relationship between CWD and any other TSE of animals or people.
Although there have been reports in the popular press of humans being affected by CWD, a study by the CDC suggests that "[m]ore epidemiologic and laboratory studies are needed to monitor the possibility of such transmissions." The epidemiological study further concludes that, "[a]s a precaution, hunters should avoid eating deer and elk tissues known to harbor the CWD agent (e.g., brain, spinal cord, eyes, spleen, tonsils, lymph nodes) from areas where CWD has been identified."
Most cases of CWD occur in adult animals. The disease
Ehrlichiosis ( /ˌɛərlɨkiˈoʊsɨs/; also known as canine rickettsiosis, canine hemorrhagic fever, canine typhus, tracker dog disease, and tropical canine pancytopenia) is a tick-borne disease of dogs usually caused by the organism Ehrlichia canis. Ehrlichia canis is the pathogen of animals. Humans can become infected by E. canis and other species after tick exposure. German Shepherd dogs are thought to be particularly affected by the disease, other breeds generally have milder clinical signs. Cats can also be infected.
Ehrlichia is a rickettsial bacteria belonging to the family Ehrlichiaceae. There are several species of Ehrlichia, but the one that most commonly affects dogs and causes the most severe clinical signs is Ehrlichia canis. This species infects monocytes in the peripheral blood. The brown dog tick, or Rhipicephalus sanguineous, that passes the organism to the dog is prevalent throughout most of the United States, but most cases tend to occur in the Southwest and Gulf Coast regions where there is a high concentration of the tick. Ehrlichia is found in many parts of the world and was first recognized in Algeria in 1935. During the Vietnam War ehrlichiosis became well known
Garre's sclerosing osteomyelitis is a type of chronic osteomyelitis also called proliferative periostitis.
It is a rare disease. It mainly affects children and young adults. It is associated with a low grade infection, which may be due to dental caries (cavities in the teeth) .
The body of the mandible may show irregular lucent/opaque changes with subperiosteal opaque layering along inferior border. It is a chronic osteomyelitis with subperiosteal bone and collagen deposition.
Glanders (from Middle English glaundres or Old French glandres, both meaning glands) (Latin: Malleus German: Rotz) (also known as "Equinia," "Farcy," and "Malleus") is an infectious disease that occurs primarily in horses, mules, and donkeys. It can be contracted by other animals such as dogs, cats and goats. It is caused by infection with the bacterium Burkholderia mallei, usually by ingestion of contaminated food or water. Symptoms of glanders include the formation of nodular lesions in the lungs and ulceration of the mucous membranes in the upper respiratory tract. The acute form results in coughing, fever and the release of an infectious nasal discharge, followed by septicaemia and death within days. In the chronic form, nasal and subcutaneous nodules develop, eventually ulcerating. Death can occur within months, while survivors act as carriers.
Glanders is endemic in Africa, Asia, the Middle East, Central and South America. It has been eradicated from North America, Australia and most of Europe through surveillance and destruction of affected animals, and import restrictions.
Burkholderia mallei is able to infect humans and is therefore classed as a zoonotic agent.
In medicine (pulmonology), psittacosis — also known as parrot disease, parrot fever, and ornithosis — is a zoonotic infectious disease caused by a bacterium called Chlamydophila psittaci (formerly Chlamydia psittaci) and contracted from parrots, such as macaws, cockatiels and budgerigars, and pigeons, sparrows, ducks, hens, gulls and many other species of bird. The incidence of infection in canaries and finches is believed to be lower than in psittacine birds.
In certain contexts, the word "psittacosis" is used when the disease is carried by any species of bird belonging to the Psittacidae family, whereas "ornithosis" is used when other birds carry the disease.
In humans, after an incubation period of 5–14 days, the symptoms of the disease range from inapparent illness to systemic illness with severe pneumonia. It presents chiefly as an atypical pneumonia. In the first week of psittacosis the symptoms mimic typhoid fever: prostrating high fevers, arthralgias, diarrhea, conjunctivitis, epistaxis and leukopenia. Rose spots can appear and these are called Horder's spots. Splenomegaly is frequent toward the end of first week. Diagnosis can be suspected in case of respiratory infection
Rocky Mountain spotted fever is the most lethal and most frequently reported rickettsial illness in the United States. It has been diagnosed throughout the Americas. Some synonyms for Rocky Mountain spotted fever in other countries include “tick typhus,” “Tobia fever” (Colombia), “São Paulo fever” or “febre maculosa” (Brazil), and “fiebre manchada” (Mexico). It is distinct from the viral tick-borne infection, Colorado tick fever. The disease is caused by Rickettsia rickettsii, a species of bacterium that is spread to humans by Dermacentor ticks. Initial signs and symptoms of the disease include sudden onset of fever, headache, and muscle pain, followed by development of rash. The disease can be difficult to diagnose in the early stages, and without prompt and appropriate treatment it can be fatal.
The name “Rocky Mountain spotted fever” is somewhat of a misnomer. Beginning in the 1930s, it became clear that this disease occurred in many areas of the United States other than the Rocky Mountain region. It is now recognized that this disease is broadly distributed throughout the contiguous United States, and occurs as far north as Canada and as far south as Central America and parts
Tinea corporis (also known as ringworm, tinea circinata, and tinea glabrosa) is a superficial fungal infection (dermatophytosis) of the arms and legs, especially on glabrous skin, however it may occur on any part of the body.
It may have a variety of appearances; most easily identifiable are the enlarging raised red rings with a central area of healing (ringworm). The same appearances of ringworm may also occur on the scalp (tinea capitis), beard area (tinea barbae) or the groin (tinea cruris, known as jock itch or dhobi itch).
Other classic features of tinea corporis include:
Tinea corporis is caused by a tiny fungus known as dermatophyte. These tiny organisms normally live on the superficial skin surface, and when the opportunity is right, they can induce a rash or infection.
The disease can also be acquired by person-to-person transfer usually via direct skin contact with an infected individual. Animal-to-human transmission is also common. Recent fossil evidence suggests that early Homo sapiens may have contracted ringworm from sharing carrion with wolves & dogs. Ringworm commonly occurs on pets (dogs, cats) and the fungus can be acquired while petting or grooming an animal.
Ascariasis is a disease of humans caused by the parasitic roundworm Ascaris lumbricoides. Perhaps as many as one quarter of the world's population are infected, with a prevalence of 45% in Latin America and 95% in parts of Africa. Ascariasis is particularly prevalent in tropical and sub-tropical regions where hygiene is poor. Other species of the genus Ascaris can cause disease in domestic animals, such as Ascaris suum which infects pigs. Some genes have been identified in humans that may increase susceptibility to infection.
Infection occurs by swallowing food contaminated with Ascaris eggs from feces. The larvae hatch in the intestine, burrow through the gut wall, and migrate to the lungs through the blood system. There they break into the alveoli and pass up the trachea and oesophagus where they are coughed up and swallowed. The larvae pass through the stomach for a second time into the intestine where they mature into adult worms. They maintain their position by swimming against the intestinal flow caused by peristalsis. Adult worms have a life-span of 1-2 years which means that individuals may be infected all their lives as worms die and new worms are acquired.
Borna disease is an infectious neurological syndrome of warm-blooded animals, caused by Borna disease virus, which causes abnormal behaviour and fatality.
The causative agent of Borna disease, Borna disease virus (BDV) is a neurotropic virus and is a member of the Bornaviridae family within the Mononegavirales order. Avian bornaviruses, a group of related viruses, have recently been identified as the cause of Proventricular Dilatation Disease, a disease of pet birds.
Although the Borna disease virus is mainly seen as the causative agent of borna disease in horses and other animals, recent findings have implicated that borna virus may play a role in some human neurological and psychiatric conditions including bipolar disorder and depression.
BDV also infects humans and is therefore considered to be a zoonotic agent. The role of BDV in human illness is controversial and it is yet to be established whether BDV causes any overt disease in humans. However, correlative evidence exists linking BDV infection with neuropsychiatric disorders such as bipolar disorder.
The mode of transmission of BDV is unclear but probably occurs through intranasal exposure to contaminated saliva or nasal
Epiglottitis is an inflammation of the epiglottis — the flap at the base of the tongue that keeps food from going into the trachea (windpipe). Due to its place in the airway, swelling of this structure can interfere with breathing, and constitutes a medical emergency. Infection can cause the epiglottis to obstruct or completely close off the windpipe.
With the advent of the Hib vaccine, the incidence of epiglottitis has decreased, but the condition has not been eliminated.
Epiglottitis commonly affects children, and it is associated with fever, difficulty in swallowing, drooling, hoarseness of voice, and typically no stridor. The child often appears acutely ill, anxious, and has very quiet shallow breathing with the head held forward, insisting on sitting up in bed. The early symptoms are insidious but rapidly progressive, and swelling of the throat may lead to cyanosis and asphyxiation.
Epiglottitis is an airway emergency and intubation is required initially. Since the introduction of the Hemophilus influenzae (Hib) vaccination in many Western countries, childhood incidence has decreased while adult incidence has remained the same; the disease is thus becoming relatively more
The Group A β-hemolytic streptococcus (Streptococcus pyogenes, or GAS) is a form of β-hemolytic Streptococcus bacteria responsible for many common infections including "strep throat" and skin infections. There are many other types of Streptococcus including Group B Streptococcus and Streptococcus pneumoniae which cause other types of infections and should not be confused with Group A Strep. Several virulence factors contribute to the pathogenesis of GAS, such as M protein, hemolysins, and extracellular enzymes.
(*Note that menigitis, sinusitis and pneumonia can all be caused by Group A Strep, but are much more commonly associated with Streptococcus pneumoniae and should not be confused.)
Complications of Group A Strep:
Acute rheumatic fever (ARF) is a complication of respiratory infections caused by GAS. The M-protein generates antibodies that cross-react with autoantigens on interstitial connective tissue, in particular of the endocardium and synovium, that can lead to significant clinical illness.
Although common in developing countries, ARF is rare in the United States, possibly secondary to improved antibiotic treatment, with small isolated outbreaks
Kyasanur forest disease (KFD) is a tick-borne viral hemorrhagic fever endemic to South Asia. The disease is caused by a virus belonging to the family flaviviridae, which also includes yellow fever and dengue fever.
The disease was first reported from Kyasanur Forest of Karnataka in India in March 1957. The disease first manifested as an epizootic outbreak among monkeys killing several of them in the year 1957. Hence the disease is also locally known as Monkey Disease or Monkey Fever. The similarity with Russian Spring-summer encephalitis was noted and the possibility of migratory birds carrying the disease was raised. Studies began to look for the possible species that acted as reservoirs for the virus and the agents responsible for transmission. Subsequent studies failed to find any involvement of migratory birds although the possibility of their role in initial establishment was not ruled out. The virus was found to be quite distinctive and not closely related to the Russian virus strains. Antigenic relatedness is however close to many other strains including the Omsk hemorrhagic fever (OHF) and birds from Siberia have been found to show an antigenic response to KFD virus.
Pelvic inflammatory disease (or disorder) (PID) is a term for inflammation of the uterus, fallopian tubes, and/or ovaries as it progresses to scar formation with adhesions to nearby tissues and organs. This can lead to infertility. PID is a vague term and can refer to viral, fungal, parasitic, though most often bacterial infections. PID should be classified by affected organs, the stage of the infection, and the organism(s) causing it. Although an STI is often the cause, many other routes are possible, including lymphatic, postpartum, postabortal (either miscarriage or abortion) or intrauterine device (IUD) related, and hematogenous spread. Two thirds of patients with laparoscopic evidence of previous PID were not aware they had PID.
In the United States, more than 750,000 women are affected by PID each year, and the rate is highest with teenagers and first time mothers. PID causes over 100,000 women to become infertile in the US each year. N. gonorrhoea is isolated in 40–60% of women with acute salpingitis. C. trachomatis is estimated to be the cause in about 60% of cases of salpingitis, which may lead to PID. However, not all PID is caused solely by STIs; organisms that are
Progressive outer retinal necrosis, also known as Varicella zoster virus retinitis (VZVR), is an aggressive, necrotizing inflammation of the eye's retina caused by herpes varicella zoster virus. It is typically found in people with advanced AIDS, but has also been reported in those who are severely immunocompromised due to chemotherapy.
The majority of those with progressive outer retinal necrosis develop severe vision loss and blindness. Systemic antiviral drugs may improve the long-term visual outcome in those with the disease.
Scabies (from Latin: scabere, "to scratch"), known colloquially as the seven-year itch, is a contagious skin infection that occurs among humans and other animals. It has been classified by the WHO as a water-related disease. It is caused by a tiny and usually not directly visible parasite, the mite Sarcoptes scabiei, which burrows under the host's skin, causing intense allergic itching. The infection in animals (caused by different but related mite species) is called sarcoptic mange.
The disease may be transmitted from objects but is most often transmitted by direct skin-to-skin contact, with a higher risk with prolonged contact. Initial infections require four to six weeks to become symptomatic. Reinfection, however, may manifest symptoms within as little as 24 hours. Because the symptoms are allergic, their delay in onset is often mirrored by a significant delay in relief after the parasites have been eradicated. Crusted scabies, formerly known as Norwegian scabies, is a more severe form of the infection often associated with immunosuppression.
The characteristic symptoms of a scabies infection include intense itching and superficial burrows. The burrow tracks are often linear,
Scarlet fever is an infectious disease which most commonly affects 4-8 year old children. Symptoms include sore throat, fever and a characteristic red rash. It is usually spread by inhalation. There is no vaccine, but the disease is effectively treated with antibiotics.
Before the availability of antibiotics, scarlet fever was a major cause of death. It could also cause late complications such as glomerulonephritis and endocarditis leading to heart valve disease, all of which were protracted and often fatal afflictions at the time.
Scarlet fever is caused by erythrogenic toxin, a substance produced by the bacterium Streptococcus pyogenes when infected by a certain bacteriophage.
The term scarlatina may be used interchangeably with scarlet fever, though it is most often used to indicate the less acute form of scarlet fever seen since the beginning of the twentieth century.
This disease is most common in 4–8 year olds with males and females being equally affected. By the age of 10 years most children have acquired protective antibodies and scarlet fever at this age or older is rare.
It is usually spread by the aerosol route (inhalation) but may also be spread by skin contact or by
Schistosomiasis (also known as bilharzia, bilharziosis or snail fever) is a parasitic disease caused by several species of trematodes (platyhelminth infection, or "flukes"), a parasitic worm of the genus Schistosoma. Snails serve as the intermediary agent between mammalian hosts. Individuals within developing countries who cannot afford proper water and sanitation facilities are often exposed to contaminated water containing the infected snails.
Although it has a low mortality rate, schistosomiasis often is a chronic illness that can damage internal organs and, in children, impair growth and cognitive development. The urinary form of schistosomiasis is associated with increased risks for bladder cancer in adults. Schistosomiasis is the second most socioeconomically devastating parasitic disease after malaria.
This disease is most commonly found in Asia, Africa, and South America, especially in areas where the water contains numerous freshwater snails, which may carry the parasite.
The disease affects many people in developing countries, particularly children who may acquire the disease by swimming or playing in infected water. When children come into contact with a contaminated
The cottontail rabbit papilloma virus (CRPV), or Shope papilloma virus, is a type I virus under the Baltimore scheme, possessing a nonsegmented dsDNA genome. It infects rabbits, causing keratinous carcinomas, typically on or near the animal’s head. These tumors can become large enough that they interfere with the host’s ability to eat, eventually causing starvation.
Shope papillomavirus provided the first mammalian model of a cancer caused by a virus. It takes its name from Dr. Richard E. Shope, who discovered it in the 1930s. Shope was able to isolate virus particles from tumors on captured animals and use these to inoculate domestic rabbits, which then developed similar tumors. The virus was sequenced in 1984, showing substantial sequence similarities to HPV1a. It has been used as a model for human papillomaviruses both before and after this discovery. The most visible example of this role is the HPV vaccine, which was developed based on and incorporating research done using the virus as a model. Similarly, it has been used to investigate antiviral therapies.
The virus is also a possible source of myths about the jackalope, a rabbit with the antlers of an antelope, and related
Human African trypanosomiasis, sleeping sickness, African lethargy, or Congo trypanosomiasis is a parasitic disease of people and animals, caused by protozoa of the species Trypanosoma brucei and transmitted by the tsetse fly. The disease is endemic in some regions of sub-Saharan Africa, covering areas in about 37 countries containing more than 60 million people. An estimated 50,000 to 70,000 people are currently infected, the number having declined somewhat in recent years. The number of reported cases was below 10,000 in 2009, the first time in 50 years. Many cases are believed to go unreported. About 48,000 people died of it in 2008. Four major epidemics have occurred in recent history: one from 1896–1906 primarily in Uganda and the Congo Basin, two epidemics in 1920 and 1970 in several African countries, and a recent 2008 epidemic in Uganda.
African trypanosomiasis symptoms occur in two stages. The first stage, known as the haemolymphatic phase, is characterized by fever, headaches, joint pains, and itching. Invasion of the circulatory and lymphatic systems by the parasites is associated with severe swelling of lymph nodes, often to tremendous sizes. Winterbottom's sign, the
Southern tick-associated rash illness (STARI) or Masters' disease is an emerging infectious disease related to Lyme disease that occurs in southeastern and south-central United States. It is spread by tick bites, but the organism that causes the infection is unknown.
This illness is a tick-borne disease carried by the Lone Star Tick Amblyomma americanum. This tick was first proposed as a possible vector of disease in 1984, and the illnesses associated with the tick called "Lyme-like disease", but it was not until the late 1990s that it was recognized that this was distinct from Lyme disease.
Several studies have failed to detect Borrelia burgdorferi, which is the causative agent of Lyme disease, in patients from the southern United States. It has therefore been proposed that this disease may be caused by the related bacterium Borrelia lonestari, which is a spirochete that was first isolated in culture in 2004. However, this conclusion is controversial since the spirochete is not detected in all cases of the syndrome, which has led some authors to argue that the illness is not caused by a bacterial pathogen.
The Centers for Disease Control is conducting a study to attempt to culture
Streptococcal pharyngitis, streptococcal tonsillitis, or streptococcal sore throat (known colloquially as strep throat) is a type of pharyngitis caused by a group A streptococcal infection. It affects the pharynx including the tonsils and possibly the larynx. Common symptoms include fever, sore throat, and enlarged lymph nodes. It is the cause of 37% of sore throats among children and 5-15% in adults.
Strep throat is a contagious infection, spread through close contact with an infected individual. A definitive diagnosis is made based on the results of a throat culture. However, this is not always needed as treatment may be decided based on symptoms. In highly likely or confirmed cases, antibiotics are useful to both prevent complications and speed recovery.
The typical symptoms of streptococcal pharyngitis are a sore throat, fever of greater than 38 °C (100 °F), tonsillar exudates (pus on the tonsils), and large cervical lymph nodes.
Other symptoms include: headache, nausea and vomiting, abdominal pain,, muscle pain,, or a scarlatiniform rash or palatal petechiae, the latter being an uncommon but highly specific finding. The incubation period and thus the start of symptoms for
Tanapox (a virus from the genus Yatapoxvirus), was first seen among individuals in the flood plain of the Tana River in Kenya during two epidemics (1957 and 1962) of acute febrile illness accompanied by localized skin lesions.
Human tanapox has been mostly documented in Kenya and Zaire, but it is believed to occur much more widely throughout tropical Africa. All age groups and both sexes appear to be affected by this virus. During the Kenyan epidemics of 1957 and 1962, cases of tanapox were reported more frequently among persons who worked or played close to the river. As a result of this, researchers concluded that tanapox is most likely a zoonosis. However, neither the reservoir host nor the mode of transmission from wild animal to human is known. It is hypothesized that tanapox virus may be transferred from monkeys or another reservoir host to humans by infected arthropods that act as mechanical vectors. Only one case of human to human transmission has been reported.
The incubation period in human cases is unknown, but in a person who underwent voluntary inoculation, erythema and central thickening appeared by the fourth day following infection.
Most patients present a mild
Dermatophytosis or ringworm is a clinical condition caused by fungal infection of the skin in humans, pets such as cats, and domesticated animals such as sheep and cattle. The term "ringworm" is a misnomer, since the condition is caused by fungi of several different species and not by parasitic worms. The fungi that cause parasitic infection (dermatophytes) feed on keratin, the material found in the outer layer of skin, hair, and nails. These fungi thrive on skin that is warm and moist, but may also survive directly on the outsides of hair shafts or in their interiors. In pets, the fungus responsible for the disease survives in skin and on the outer surface of hairs.
It has been estimated that currently up to twenty percent of the population may be infected by ringworm or one of the other dermatophytoses. It is especially common among people who play sports, wrestling in particular. Wrestlers with ringworm may be withheld from competition until their skin condition is deemed non-infectious by the proper authorities.
Misdiagnosis and treatment of ringworm with a topical steroid, a standard treatment of the superficially similar pityriasis rosea, can result in tinea incognito, a
Tinea barbæ (also known as "Barber's itch," "Ringworm of the beard," and "Tinea sycosis") is a fungal infection of the hair. Tinea barbae is due to a dermatophytic infection around the bearded area of men. Generally, the infection occurs as a follicular inflammation, or as a cutaneous granulomatous lesion, i.e. a chronic inflammatory reaction. It is one of the causes of Folliculitis. It is most common among agricultural workers, as the transmission is more common from animal-to-human than human-to-human. The most common causes are T. mentagrophytes and T. verrucosum.
Venezuelan hemorrhagic fever (VHF) is a zoonotic human illness first identified in 1989. The disease is most prevalent in several rural areas of central Venezuela and is caused by the Guanarito (GTOV) arenavirus belonging to the Arenaviridae family. The short-tailed cane mouse (Zygodontomys brevicauda) is the main host for GTOV which is spread mostly by inhalation of aerosolized droplets of saliva, respiratory secretions, urine, or blood from infected rodents . Person-to-person spread is possible, but uncommon.
From September 1989 through December 2006, the State of Portuguesa recorded 618 cases of VHF. Nearly all of the cases were individuals who worked or lived in Guanarito during the time they became infected. The case fatality rate was 23.1% .
Because the virus is contracted by aerosol dissemination, concern arose shortly after the first cases emerged in 1989 due to fear of biological warfare. Potential biological terrorism agents were identified and categorized in 1999 by the Centers for Disease Control and Prevention (CDC) as part of the Congressional initiative to further response capabilities to biological weapons  . Arenaviruses causing hemorrhagic fevers, along with
Verruca plana, also known as a "flat wart", is a reddish-brown or flesh-colored, slightly raised, flat-surfaced, well-demarcated papule of 2 to 5 mm in diameter. Upon close inspection, these lesions have a surface that is "finely verrucous". Most often, these lesions affect the hands or face, and a linear arrangement is not uncommon.
The Western equine encephalomyelitis virus is the causative agent of relatively uncommon viral disease Western equine encephalomyelitis (WEE). An Alphavirus of the family Togaviridae, the WEE virus is an arbovirus (arthropod-borne virus) transmitted by mosquitoes of the genera Culex and Culiseta. WEE is a recombinant virus between two other closely related yet distinct encephalitis viruses. There have been under 700 confirmed cases in the U.S. since 1964.
In the U.S. WEE is seen primarily in states west of the Mississippi River. The disease is also seen in countries of South America. WEE is commonly a subclinical infection; symptomatic infections are uncommon. However, the disease can cause serious sequelae in infants and children. Unlike Eastern equine encephalitis, the overall mortality of WEE is low (approximately 4%) and is associated mostly with infection in the elderly. There is no vaccine for WEE and there are no licensed therapeutic drugs in the U.S. for this infection.
Western equine encephalitis virus was one of more than a dozen agents that the United States researched as potential biological weapons before the nation suspended its biological weapons program.
Yellow fever (also known as Yellow Jack and Bronze John) is an acute viral hemorrhagic disease. The virus is a 40 to 50 nm enveloped RNA virus with positive sense of the Flaviviridae family.
The yellow fever virus is transmitted by the bite of female mosquitoes (the yellow fever mosquito, Aedes aegypti, and other species) and is found in tropical and subtropical areas in South America and Africa, but not in Asia. The only known hosts of the virus are primates and several species of mosquito. The origin of the disease is most likely to be Africa, from where it was introduced to South America through the slave trade in the 16th century. Since the 17th century, several major epidemics of the disease have been recorded in the Americas, Africa, and Europe. In the 19th century, yellow fever was deemed one of the most dangerous infectious diseases.
Yellow fever presents in most cases with fever, nausea, and pain, and it generally subsides after several days. In some patients, a toxic phase follows, in which liver damage with jaundice (inspiring the name of the disease) can occur and lead to death. Because of the increased bleeding tendency (bleeding diathesis), yellow fever belongs to the