Cholera is an acute, diarrheal illness caused by infection of the intestine with the bacterium Vibrio cholerae. The infection is often mild or without symptoms, but sometimes it can be severe. Approximately one in 20 infected persons has severe disease characterized by profuse watery diarrhea, vomiting, and leg cramps. In these persons, rapid loss of body fluids leads to dehydration and shock. Without treatment, death can occur within hours.

Spread by contaminated water. The bacteria appears in feces of infected persons. Inadequate sewage and drinking water treatment can spread the disease quickly.

6,000 died in 60 days in New Orleans from Cholera in 1832. Many of these were Irish immigrants living in the Irish Channel.

Fear of a cholera outbreak after the Katrina flooding was a significant contributor to the decision for mandatory evacuations after the storm.