Cholera is contracted when people drink water or eat food that has been fecally contaminated by the bacteria.
The most common sources are:
- Surface or well water. Cholera bacteria can lie dormant in water for long periods, and contaminated public wells are frequent sources of large-scale cholera outbreaks. Cholera outbreaks are most likely to occur in communities where there is no adequate sanitation, areas affected by natural disasters or war. Overcrowded refugee camps are also a risk.
- Seafood. Eating raw or uncooked seafood especially shellfish from certain locations can expose you to cholera. Most cases of cholera in the US since 1970s have been traced to oysters and crab and seafood smuggled or transported from cholera endemic countries. Shellfish filter large amounts of water, concentrating the levels of cholera bacteria.
- Raw fruits and vegetables. Raw, unpeeled fruits and vegetables are a source of infection on areas where cholera is endemic. In developing nations, uncomposted manure fertilizers or irrigation water containing raw sewage can contaminate produce in the field. They may also become tainted with cholera during harvesting or processing.
- Grains. In cholera endemic regions grains such as rice and millet are contaminated after cooking and allowed to remain at room temperature for several hours become a medium for the growth of bacteria.