Cholera is an acute illness characterized by watery diarrhea. The toxin released by the bacteria causes increased secretion of water and chloride ions in the intestine, which can produce massive diarrhea. Death can result from the severe dehydration brought on by the diarrhea.

Cholera occurs in epidemics when conditions of poor sanitation, crowding, war, and famine are present. Endemic areas include India, Asia, Africa, the Mediterranean, and more recently, South and Central America, and Mexico. The infection is acquired by ingesting contaminated food or water.

A type of Vibrio bacteria also has been associated with shellfish, especially raw oysters. Risk factors include residence or travel in endemic areas and exposure to contaminated or untreated drinking water.