It's the first outbreak in the western hemisphere in 20 years.
Cholera has struck more than 1,500people in Haiti. 142 have died.
Dirty water flowing through the country's streets during the rainy season is spreading the disease.
Cholera is a bacterial infection that causes diarrhea and dehydration so severe victims can lose more than a quart of water in one hour. It can kill patients in one day.
World Health Officials say they have enough medicine to treat 100,000 cases, but there are question as to whether they can reach the people in time.