CHOLERA

acute bacterial infection of the small intestine, caused by Vibrio cholerae and characterized by massive diarrhea with rapid and severe depletion of body fluids and salts. Cholera often rises to epidemic proportions in Southeast Asia, particularly in India and Pakistan, having been responsible for at least 370,000 deaths in India in the period from 1898 to 1907. In the 1980s and 1990s cholera spread among the crowded refugee camps and city slums of famine-stricken countries in Africa, particularly Ethiopia and The Sudan. Following a 70-year absence from the Western Hemisphere, there was a major outbreak of cholera in Peru in 1991. The vibrio enters the body via the mouth, usually in contaminated water or foods, and causes an infection in the mucous membranes lining the lumen of the small intestine. The diarrhea is caused by the action of the Vibrio cholerae toxin in the intestine. This toxin combines with a substance in the cells of the intestinal wall, activating an enzyme system that causes the rapid excretion of body fluids containing bicarbonate and sodium. After an incubation period of 12 to 28 hours, the disease usually starts with an abrupt, painless, watery diarrhea that may amount to a volume of 15 to 20 litres (3 to 4 gallons) or more in 24 hours. This purging diarrhea is soon followed by vomiting, and the patient rapidly becomes dehydrated; the skin becomes cold and withered, and the face is drawn; the blood pressure falls, and the pulse becomes faint; muscular cramps may be severe, and thirst intense. As dehydration increases, the person becomes stuporous and comatose and may die in shock. The disease ordinarily runs its course in two to seven days. With prompt fluid and salt repletion, which is accomplished by the oral or intravenous administration of an alkaline solution of sodium chloride, recovery can be remarkably rapid; but if therapy is inadequate, the mortality rate is high. The administration of antibiotics during the first day of treatment usually shortens the period of diarrhea and decreases the requirement for fluid replacement. The prevention of cholera outbreaks rests upon better sanitation, particularly the use of clean drinking water. Immunization with a vaccine of killed vibrio bacteria provides partial protection in individuals for a limited time, but its use on a massive scale does not prevent the spread of infection. This can be accomplished only by attacking the source of the infection, usually the water supply.