Instruct: Given a question, retrieve relevant documents that answer the question.
Query: Does melioidosis affect humans?
A definite history of contact with soil may not be elicited, as melioidosis can be dormant for many years before manifesting. Attention should be paid to a history of travel to endemic areas in returned travellers. Some authors recommend considering possibility of melioidosis in every febrile patient with a history of traveling to and/or staying at endemic areas.
Based on whole genome sequencing, humans may play a role in moving "B. pseudomallei" from place to place.
Plasmodium falciparum is a unicellular protozoan parasite of humans, and the deadliest species of "Plasmodium" that cause malaria in humans. It is transmitted through the bite of a female "Anopheles" mosquito. It is responsible for roughly 50% of all malaria cases. It causes the disease's most dangerous form called falciparum malaria. It is therefore regarded as the deadliest parasite in humans, causing 435,000 deaths in 2017. It is also associated with the development of blood cancer (Burkitt's lymphoma) and is classified as Group 2A carcinogen.
Leptospirosis is a water contract disease caused by bacteria of the genus Leptospirabacterial. It is a disease that affects both humans and animals. The number of leptospirosis cases had steadily increased from 2011 (2,268 cases with 55 death) to 2015 (8,291 cases with 78 death) and 5,284 cases with 52 death in 2016. Leptospirosis can have important health impact and is a burden to the nation if not well controlled. Addressing leptospisoris includes maintain a clean environment and by not swimming or wading in water that might be contaminated with animal urine, or eliminating contact with potentially infected animals.
Pathologist Alfred Whitmore and assistant Krishnaswami first reported the disease among beggars and morphine addicts at autopsy in Rangoon, present-day Myanmar, in a report published in 1912. They distinguished it from glanders, a disease of humans and animals that is similar in presentation, but caused by a different micro-organism. "B. pseudomallei", also known as the Whitmore bacillus, was identified in 1917 in Kuala Lumpur. Arthur Conan Doyle may have read the 1912 report before writing a short story that involved the fictitious tropical disease "tapanuli fever" in a Sherlock Holmes adventure.
"O. tsutsugamushi" causes a complex and dangerous infection scrub typhus. Infection starts when chiggers bite on the skin during their feeding. The bacteria are deposited at the site of feeding (inoculation), where they multiply. They cause progressive tissue damage (necrosis). Necrosis progresses to inflammation of the blood vessels called vasculitis. This in turn causes inflammation of the lymph nodes, called lymphadenopathy. Within a few days, vasculitis extends to various organs including liver, brain, kidney, meninges and the lung. The disease is responsible for nearly a quarter of all the febrile (high fever) illness in endemic areas. Mortality in severe case or due to improper treatment or misdiagnosis may be as high as 30-70%. About 6% of infected people die untreated, and 1.4% of the patients die even with medical treatment. Moreover, death rate can be as high as 13% where medical treatment is not properly handled. In cases of misdiagnosis and failure of treatment, systemic complications rapidly develop including acute respiratory distress syndrome, acute kidney failure, encephalitis, gastrointestinal bleeding, hepatitis, meningitis, myocarditis, pancreatitis, pneumonia, septic shock, sub-acute thyroiditis, and multi-organ dysfunctions. Harmful symptoms involving multiple organ failure and neurological impairment are difficult to treat, and can be lifelong debilitation or directly fatal. The central nervous system is often affected and result in various complications including cerebellitis, cranial nerve palsies, meningoencephalitis, plexopathy, transverse myelitis, neuroleptic malignant syndrome, and Guillan-Barré syndrome. Death rates due to complications can be up to 14% in brain infections, and 24% with multiple organ failure. It is the major cause of acute encephalitis syndrome in India, where viral infection Japanese encephalitis has been regarded as the main factor.
Bovine spongiform encephalopathy (BSE), commonly known as "mad cow disease", is a fatal, neurodegenerative disease of cattle, which infects by a mechanism that surprised biologists upon its discovery in the late 20th century. In the UK, the country worst affected, 179,000 cattle were infected and 4.4 million killed as a precaution. The disease can be transmitted to human beings who eat or inhale material from infected carcasses. In humans, it is known as new variant Creutzfeldt–Jakob disease (vCJD or nvCJD), and by June 2007, it had killed 165 people in Britain, and six elsewhere with the number expected to rise because of the disease's long incubation period. 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.
The causative pathogen was first identified by Naosuke Hayashi in 1920. Confident that the organism was a protozoan, Hayashi concluded, stating, "I have reached the conclusion that the virus of the disease is the species of "Piroplasma" [protozoan] in question... I consider the organism in Tsutsugamushi disease as a hitherto undescribed species, and at the suggestion of Dr. Henry B. Ward designate it as "Theileria tsutsugamushi"." Discovering the similarities with the bacterium "Rickettsia prowazekii", Mataro Nagayo and colleagues gave a new classification with the name "Rickettsia orientalis" in 1930. ("R. prowazekii" is a causative bacterium of epidemic typhus first discovered by American physicians Howard Taylor Ricketts and Russell M. Wilder in 1910; and described by a Brazilian physician Henrique da Rocha Lima in 1916.)
Swimming in the pool at the bottom of the falls is discouraged. This is due both to occasional rockfalls and to the bacterial disease called Leptospirosis, which causes severe flu-like symptoms. Leptospirosis is found in freshwater and is common in tropical climates. In Hawaii, rats and mice often carry the disease and can easily transfer it to humans through their urine.
A few strains from organisms genetically identified as other "Clostridium" species have caused human botulism: "C. butyricum" has produced type E toxin and "C. baratii" had produced type F toxin. The ability of "C. botulinum" to naturally transfer neurotoxin genes to other clostridia is concerning, especially in the food industry, where preservation systems are designed to destroy or inhibit only "C. botulinum" but not other "Clostridium" species.
Plasmodium vivax is a protozoal parasite and a human pathogen. This parasite is the most frequent and widely distributed cause of recurring (Benign tertian) malaria, "P. vivax" is one of the five species of malaria parasites that commonly infect humans. Although it is less virulent than "Plasmodium falciparum", the deadliest of the five human malaria parasites, "P. vivax" malaria infections can lead to severe disease and death, often due to splenomegaly (a pathologically enlarged spleen). "P. vivax" is carried by the female "Anopheles" mosquito; the males do not bite.
Mosquito-borne diseases or mosquito-borne illnesses are diseases caused by bacteria, viruses or parasites transmitted by mosquitoes. They can transmit disease without being affected themselves. Nearly 700 million people get a mosquito-borne illness each year resulting in over one million deaths.
Some golden jackals carry diseases and parasites harmful to human health. These include rabies, and Donovan's "Leishmania" that is harmless to jackals but may cause leishmaniasis in people. Jackals in southwestern Tajikistan can carry up to 16 species of parasitic cestodes (flatworm), roundworms, and acanthocephalans (thorny-headed worms), these are: "Sparganum mansoni", "Diphyllobothrium mansonoides", "Taenia hydatigena", "T.pisiformis", "T.ovis", "Hydatigera taeniaeformis", "Dipylidium caninum", "Mesocestoides lineatus", "Ancylostoma caninum", "Uncinaria stenocephala", "Dioctophyma renale", "Toxocara canis", "Toxascaris leonina", "Dracunculus medinensis", "Filariata" and "Macracanthorhynchus catulinum". Jackals infected with "Dracunculus medinensis" can infect bodies of water with their eggs, which cause dracunculiasis in people who drink from them. Jackals may also play a large part in spreading coenurosis in sheep and cattle, and canine distemper in dogs. In Tajikistan, jackals may carry up to 12 tick species (which include "Ixodes", "Rhipicephalus turanicus", "R.leporis", "R.rossicus", "R. sanguineus", "R.pumilio", "R.schulzei", "Hyalomma anatolicum", "H.scupense" and "H.asiaticum"), four flea species ("Pulex irritans", "Xenopsylla nesokiae", "Ctenocephanlides canis" and "C.felis"), and one species of louse ("Trichodectes canis").
Canine distemper is caused by a single-stranded RNA virus of the family "Paramyxoviridae" (the same family of the viruses that causes measles, mumps, and bronchiolitis in humans). The disease is highly contagious via inhalation. Morbidity and mortality may vary greatly among animal species, with up to 100% mortality in unvaccinated populations of ferrets. In domestic dogs, while the acute generalized form of distemper has a high mortality rate, disease duration and severity depends mainly on the animal's age and immune status and virulence of the infecting strain of the virus. Despite extensive vaccination in many regions, it remains a major disease of dogs, and was the leading cause of infectious disease death in dogs, prior to a vaccine becoming available.
Klebs made some significant errors about infectious diseases. He believed, for example, that malaria was caused by a bacterium. In 1879, Corrado Tommasi-Crudeli and he claimed that they isolated a bacterium from the waters of Pontine Marshes in Roman Campagna. They concluded that the bacterium was the pathogen for malaria as they discovered it from damp soil in the region of malaria epidemics. They gave it the name "Bacillus malariae". They further experimented with the bacterial isolate which they injected into rabbits. They observed that infected rabbits developed fever and enlarged spleen, characteristics of malaria. They proposed that the malarial bacterium was transmitted by drinking contaminated water or inhalation from air. Klebs reported that antimalarial drug quinine killed the germ. The discovery was supported by leading malariologists of the time. It was then declared that the malaria problem was solved. When a French Army physician Charles Alphonse Laveran correctly discovered in 1880 that malaria was caused by a protozoan parasite (which he called "Oscillaria malariae", now "Plasmodium falciparum"), the discovery was ignored in preference of the bacillus theory of Klebs and Tommasi-Crudeli. An American physician, though, George Miller Sternberg, proved that the bacillus did not cause specific symptoms of malaria in 1881. The bacillus theory was eventually proved wrong by the experimental demonstration of the mosquito-malaria theory in 1898.
Humans become infected through contact with water, food, or soil that contains urine from these infected animals. This may happen by swallowing contaminated food or water or through skin contact. The disease is not known to spread between humans, and bacterial dissemination in convalescence is extremely rare in humans. Leptospirosis is common among water-sport enthusiasts in specific areas, as prolonged immersion in water promotes the entry of this bacterium. Surfers and whitewater paddlers are at especially high risk in areas that have been shown to contain these bacteria, and can contract the disease by swallowing contaminated water, splashing contaminated water into their eyes or nose, or exposing open wounds to infected water.
In tropical and semi tropical areas, like South and South-east Asia the disease is increasingly seen as epidemics after heavy rains, sometimes after flooding. Periods of heavy rain followed by days of little or no rain seemed to be the setting for leptospirosis epidemics in this part of the world. Most cases seemed to occur by cutaneous exposure of the legs while walking in stagnant water or moist soil. The presence of wounds or fissures on the legs are a risk factor for acquiring the infection.
The botulinum toxin can cause a severe flaccid paralytic disease in humans and other animals and is the most potent toxin known to mankind, natural or synthetic, with a lethal dose of 1.3–2.1 ng/kg in humans.
Botulinum toxin produced by "Clostridium botulinum" is the cause of botulism. Humans most commonly ingest the toxin from eating improperly-canned foods in which "C. botulinum" has grown. However, the toxin can also be introduced through an infected wound. In infants, the bacteria can sometimes grow in the intestines and produce botulinum toxin within the intestine and can cause a condition known as floppy baby syndrome. In all cases, the toxin can then spread, blocking nerves and muscle function. In severe cases, the toxin can block nerves controlling the respiratory system or heart, resulting in death.
The disease has been notifiable in the EU since 1993 but unlike BSE there was no evidence as of 1999 to suggest that scrapie is a risk to human health. In July 2003, a Canadian Food Inspection Agency officer said that while scrapie shows up every year on Canadian farms, "We've had a lot of experience with scrapie and there's never been a link between scrapie and human illness." As of 2004, the USDA made no mention of scrapie in its "Sheep and Goats Death Loss" circular.
A French Army physician Charles Louis Alphonse Laveran discovered that malaria was caused by microscopic parasite (now called "Plasmodium falciparum") in 1880. But scientists were sceptical until Golgi intervened. It was Golgi who helped him prove that malarial parasite was a microscopic protozoan. From 1885, Golgi studied the malarial parasite and its transmission. He established two types of malaria, tertian and quartan fevers caused by "Plasmodium vivax" and "Plasmodium malariae" respectively. In 1886, he discovered that malarial fever (paroxysm) was produced by the asexual stage in the human blood (called erythocytic cycle, or Golgi cycle). In 1889-1890, Golgi and Ettore Marchiafava described the differences between benign tertian malaria and malignant tertian malaria (the latter caused by "P. falciparum"). By 1898, along with Giovanni Battista Grassi, Amico Bignami, Giuseppe Bastianelli, Angelo Celli and Marchiafava, he confirmed that malaria was transmitted by "Anopheline" mosquito.
Leptospirosis, also known as field fever is an infection caused by "Leptospira". Symptoms can range from none to mild such as headaches, muscle pains, and fevers; to severe with bleeding from the lungs or meningitis. "Leptospira" is transmitted by both wild and domestic animals, most commonly by rodents. It is often transmitted by animal urine or by water or soil containing animal urine coming into contact with breaks in the skin, eyes, mouth, or nose.
The countries with the highest reported incidence are located in the Asia-Pacific region (Seychelles, India, Sri Lanka and Thailand) with incidence rates over 10 per 1000,000 people s well as in Latin America and the Caribbean (Trinidad and Tobago, Barbados, Jamaica, El Salvador, Uruguay, Cuba, Nicaragua and Costa Rica) However, the rise in global travel and eco-tourism has led to dramatic changes in the epidemiology of leptospirosis, and travelers from around the world have become exposed to the threat of leptospirosis. Despite decreasing prevalence of leptospirosis in endemic regions, previously non-endemic countries are now reporting increasing numbers of cases due to recreational exposure International travelers engaged in adventure sports are directly exposed to numerous infectious agents in the environment and now comprise a growing proportion of cases worldwide.
"B. pseudomallei" infection in humans is called melioidosis; its mortality is 20 to 50% even with treatment.
In up to 25% of patients, no focus of infection is found and the diagnosis is usually made on blood cultures or throat swab. Melioidosis is said to be able to affect any organ in the body except the heart valves (endocarditis). Although meningitis has been described secondary to ruptured brain abscesses, primary meningitis has not been described. Less common manifestations include intravascular infection, lymph node abscesses (1.2–2.2%), pyopericardium and myocarditis, mediastinal infection, and thyroid and scrotal abscesses and ocular infection.
A complete screen (blood culture, sputum culture, urine culture, throat swab, and culture of any aspirated pus) should be performed on all patients with suspected melioidosis (culture on blood agar as well as Ashdown's medium). A definitive diagnosis is made by growing "B. pseudomallei" from any site. A throat swab is not sensitive, but is 100% specific if positive, and compares favourably with sputum culture. The sensitivity of urine culture is increased if a centrifuged specimen is cultured, and any bacterial growth should be reported (not just growth above 10 organisms/ml which is the usual cutoff). Very occasionally, bone marrow culture may be positive in patients who have negative blood cultures for "B. pseudomallei", but these are not usually recommended. A common error made by clinicians unfamiliar with melioidosis is to send a specimen from only the affected site (which is the usual procedure for most other infections) instead of sending a full screen.
The single most important risk factor for developing melioidosis is diabetes mellitus, followed by hazardous alcohol use, chronic kidney disease, and chronic lung disease. Other risk factors include thalassaemia, occupation (rice paddy farmers), and cystic fibrosis. The mode of infection is believed to be through either a break in the skin, or the inhalation of aerosolized "B. pseudomallei" cells. Person-to-person spread has been described, but is extremely unusual. HIV infection does not predispose to melioidosis.