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''Vibrio cholerae'' is a Gram-negative, comma-shaped bacterium. Initial isolates are slightly curved, whereas they can appear as straight rods upon laboratory culturing. The bacterium's natural habitat is brackish or saltwater. Some strains of ''V. cholerae'' cause the disease cholera. ''V. cholerae'' is a facultative anaerobic organism〔(【引用サイトリンク】url=http://www.cdc.gov/cholera/pdf/laboratory-methods-for-the-diagnosis-of-vibrio-cholerae-chapter-6.pdf )〕 and has a polar flagellum at one cell pole as well as pili. ''V. cholerae'' can undergo respiratory and fermentative metabolism. It is one of the most devastating human diseases, with a rapid onset of diarrhea and vomiting within several hours to 2-3 days of ingestion. Due to massive fluid losses (15-20 liters/day), the untreated mortality rate is in excess of sixty percent. However, rehydration therapy brings the mortality rate to below one percent. ''V. cholerae'' was first isolated as the cause of cholera by Italian anatomist Filippo Pacini in 1854,〔See: * Filippo Pacini (1854) ("Osservazioni microscopiche e deduzioni patologiche sul cholera asiatico" ) (Microscopic observations and pathological deductions on Asiatic cholera), ''Gazzetta Medica Italiana: Toscana'', 2nd series, 4 (50) : 397-401 ; 4 (51) : 405-412. The term "vibrio cholera" appears on page 411. * Reprinted (more legibly) as a (pamphlet. )〕 but his discovery was not widely known until Robert Koch, working independently 30 years later, publicized the knowledge and the means of fighting the disease. ==Pathogenesis== ''V. cholerae'' pathogenicity genes code for proteins directly or indirectly involved in the virulence of the bacteria. During infection, ''V. cholerae'' secretes cholera toxin, a protein that causes profuse, watery diarrhea. Colonization of the small intestine also requires the toxin coregulated pilus (TCP), a thin, flexible, filamentous appendage on the surface of bacterial cells. ''V. cholerae'' can cause syndromes ranging from asymptomatic to cholera gravis.〔 In endemic areas, 75% of cases are asymptomatic, 20% are mild to moderate, and 2-5% are severe forms such as cholera gravis.〔 Symptoms include abrupt onset of watery diarrhea (a grey and cloudy liquid), occasional vomiting, and abdominal cramps.〔〔 Dehydration ensues, with symptoms and signs such as thirst, dry mucous membranes, decreased skin turgor, sunken eyes, hypotension, weak or absent radial pulse, tachycardia, tachypnea, hoarse voice, oliguria, cramps, renal failure, seizures, somnolence, coma, and death.〔 Death due to dehydration can occur in a few hours to days in untreated children. The disease is also particularly dangerous for pregnant women and their fetuses during late pregnancy, as it may cause premature labor and fetal death.〔 In cases of cholera gravis involving severe dehydration, up to 60% of patients can die; however, less than 1% of cases treated with rehydration therapy are fatal. The disease typically lasts 4–6 days.〔 Worldwide, diarrhoeal disease, caused by cholera and many other pathogens, is the second-leading cause of death for children under the age of 5 and at least 120,000 deaths are estimated to be caused by cholera each year. In 2002, the WHO deemed that the case fatality ratio for cholera was about 3.95%.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「vibrio cholerae」の詳細全文を読む スポンサード リンク
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