Cholera is a severe form of bacterial dysentery that can thrive under conditions of squalor and poor sanitation.
In its most severe form, cholera causes profuse watery diarrhea and vomiting. In turn, these symptoms can lead to dehydration, collapse of the circulatory system and death within a few hours of onset.
Death rates of 50 percent have been recorded in epidemics.
But if fluid loss is promptly corrected intravenously or by drinking oral rehydration solutions, the death rate falls to less than 1 percent.
Cholera vaccines offer protection in only about 50 percent of people and are of little practical value in controlling an epidemic. The most effective methods of prevention are standard hygiene measures such as washing hands, boiling water, improving sanitation and disinfection.
But such steps can be nearly impossible to take when hordes of people invade and camp out in an area where water, food and sanitation are scarce.