"Vibrio cholerae, the bacterium responsible for cholera, may have been dormant in water until weather-related conditions caused it to multiply enough to constitute an infective dose if ingested by humans," said David Sack, a cholera specialist at Johns Hopkins University Bloomberg School of Public Health, United States

Medically, cholera is easy to prevent and treat. But in Haiti, it is proving impossible to control. What Haiti needs to combat cholera is a functioning water and sewage system.