cholera (redirected from epidemic cholera)

cholera (kŏl`ərə) or Asiatic cholera, acute infectious disease caused by strains of the bacterium Vibrio cholerae that have been infected by bacteriophages. The bacteria, which are found in fecal-contaminated food and water and in raw or undercooked seafood, produce a toxin that affects the intestines causing diarrhea, vomiting, and severe fluid and electrolyte loss. This overwhelming dehydration is the outstanding characteristic of the disease and is the main cause of death. Cholera has a short incubation period (two or three days) and runs a quick course. In untreated cases the death rate is high, averaging 50%, and as high as 90% in epidemics, but with effective treatment the death rate is less than 1%. The intravenous and oral replacement of body fluids and essential electrolytes and the restoration of kidney function are more important in therapy than the administration of antibacterial drugs. In regions of Asia, Africa, and South America where public sanitation is poor the disease is still endemic or epidemic; vaccination is recommended for people living in those areas. A theory of evolutionary biologists holds that the cystic fibrosis gene, a common but lethal recessive gene carried by approximately one in twenty Caucasians, affords those carriers partial protection against cholera.

Bibliography

See C. E. Rosenberg, The Cholera Years (1962).

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cholera

Acute bacterial infection with Vibrio cholerae, causing massive diarrhea with severe depletion of body fluids and salts. (See bacterial disease.) Cholera often occurs in epidemics, spreading in contaminated water or food. The bacteria secrete a toxin that causes the diarrhea, which along with vomiting leads to dehydration, with severe muscle cramps and intense thirst. Stupor and coma may precede death by shock. With fluid and salt replacement, the disease passes in two to seven days, sooner if antibiotics are taken the first day. Prevention requires good sanitation, especially clean drinking water.

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cholera

an acute intestinal infection characterized by severe diarrhoea, cramp, etc.: caused by ingestion of water or food contaminated with the bacterium Vibrio comma

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cholera [′käl·ə·rə]

(medicine)

An acute, infectious bacterial disease of humans caused byVibrio comma;characterized by diarrhea, delirium, stupor, and coma.

Any condition characterized by profuse vomiting and diarrhea.

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cholera [′käl·ə·rə]

(medicine)

An acute, severe gastroenteritis.

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Cholera

A severe diarrheal disease caused by infection of the small bowel of humans with Vibrio cholerae, a facultatively anaerobic, gram-negative, rod-shaped bacterium. Cholera is transmitted by the fecal-oral route. Cholera has swept the world in seven pandemic waves. These involved the Western Hemisphere several times in the 1800s, and again in Peru in 1991. Whereas previous cholera outbreaks were associated with high mortality rates, through understanding of its pathophysiology it can now be said that no one should die of cholera who receives appropriate treatment soon enough.

Cholera produces a secretory diarrhea caused by the protein cholera enterotoxin (CTX). The toxin causes hypersecretion of chloride and bicarbonate and inhibition of sodium absorption in host membranes leading to the secretion of the large volumes of isotonic fluid which constitute the diarrhea of severe cholera. Treatment consists of replacing the fluids and electrolytes lost in the voluminous cholera stool. This can be done intravenously or orally. Appropriate antibiotics can also be used. The incubation period may be less than one day or up to several days; properly treated, the patient should recover in 4 or 5 days. The disease produces immunization, and convalescents rarely get cholera again.

Despite the fact that the cholera bacteria were first discovered by Robert Koch in 1883 and a cholera vaccine was introduced 3 years later, there is still no effective, economical, and nonreactogenic vaccine. Use of a killed whole-cell vaccine administered parenterally (via injection) was eliminated because of expense, reactogenicity, and lack of efficacy. Experimental vaccines currently being evaluated include genetically engineered living attentuated preparations administered orally (or intranasally), killed whole-cell vaccines administered orally, and conjugated vaccines (polysaccharide and toxin antigens) administered parenterally. Efforts are also being made to include cholera antigens transgenically in edible plants.

A complicating feature is the fact that of approximately 150 recognized serogroups of V. cholerae, until 1992 only two, classical (first described by Koch) and El Tor (recognized later), of serogroup O1 have been responsible for all epidemic cholera. In 1992 a recently recognized serogroup, O139, caused epidemic cholera in India and Bangladesh and, for a time, replaced the resident El Tor vibrios. O139 and El Tor are antigenically distinct, so a new vaccine will be required for O139. The emergence of O139 raises the specter that other serogroups of V. cholerae may acquire virulence and epidemicity.

The best ways to avoid cholera are by chlorination of water, sanitary disposal of sewage, and avoidance of raw or improperly cooked seafood, which may have become infected by ingesting infected plankton in epidemic areas.