The definitions used in this glossary of terminology either have been provided by the authors of the articles, or have been extracted wholly or in part, or paraphrased from the following sources: The American Medical Association Encyclopedia of Medicine, Charles B. Clayman, MD, Medical Editor, Random House, New York, 1989; Biotechnology from A to Z, 2d Edition, William Bains, Oxford University Press, New York, New York, 2002; A Dictionary of Genetics, 6th Edition, Robert C. King and William D. Stansfield, Oxford University Press, New York, New York, 2002; Dorland's Illustrated Medical Dictionary, 29th and 30th Editions, W. B. Saunders Company, Philadelphia, 2000, 2003; Genes VII, Benjamin Lewin, Oxford University Press, New York, New York, 2000; The Gale Encyclopedia of Genetic Disorders, Volumes I and II, Stacey L. Blachford, Ed., Thomson Learning, New York, New York, 2002; The Merriam-Webster Dictionary, Merriam-Webster, Inc., Springfield, Massachusetts, 1997; Molecular Biology of the Cell, 3rd Edition, Bruce Alberts, et al., Garland Publishing, 1994; The Random House Dictionary of the English Language, Unabridged Edition, 1966; Webster's Ninth New Collegiate Dictionary, 1991.

DEFINITION:

cholera

An infection of the small intestine caused by the bacterium Vibrio Cholerae (a vibrio is a comma-shaped bacterium). Cholera results in profuse watery diarrhea that in severe untreated cases can lead to rapid dehydration and death. Infection is always acquired by swallowing food or water that has been contaminated with the vibrio.

Symptoms
Cholera starts suddenly, between one and five days after infection, with diarrhea, often accompanied by vomiting. Over a pint of fluid may be lost each hour in the diarrhea and, if not replaced, this loss of fluid causes death within a few hours. The fluid loss is brought about by the action of a toxin produced by a bacterium that greatly increases the passage of fluid from the bloodstream into the large and small intestines.

Treatment
Cholera is treated by replacing the lost fluid with drinks of water containing the correct proportions of various salts and sugar. If dehydration develops despite fluid replacement by mouth, the patient may be given extra fluid by means of intravenous infusion. Antibiotics, such as tetracycline hydrochloride, can shorten the period of diarrhea and infectiousness to others.

Given adequate rehydration, patients usually make a full recovery. In major epidemics following natural disasters, sufficient supplies of clean water may not be available---or so many people become ill simultaneously that there are few left to nurse the sick.

Prevention
Worldwide, cholera is controlled by improving sanitation---in particular by ensuring that sewage is not allowed to contaminate water supplies that will later be used for drinking. Travelers to cholera-infected areas should either restrict themselves to bottled drinks or boil all water before drinking.

A vaccine that provides some protection against the disease is advisable when traveling to Africa and to the Middle and Far East. The protection it gives is short-lived (six months) and precautions still must be taken with drinking water. International travelers should check vaccination requirements before departure to cholera-infected areas.