Although the causes of cholera are generally well known, it continues to be a problem in some parts of the world. Cholera is an intestinal disease caused by the Vibrio cholerae bacteria that can contaminate water, uncooked fruits and vegetables and raw shellfish. Infection can cause serious diarrhea, which in turn can lead to potentially lethal dehydration. Cholera bacteria occur naturally in coastal waters and spread via their host crustaceans that move about following the algae on which they feed.
Eating raw or undercooked seafood, especially shellfish from certain areas, is one of the causes of cholera. Since the 1970s, most cases of cholera in the United States were found to be the result of eating oysters and crabs harvested in the Gulf of Mexico or imported from countries where cholera is a widespread and ongoing problem. Shellfish are more likely to be infected with cholera bacteria than other types of seafood because they must filter large amounts of water in order to extract food; this action concentrates the bacteria in their bodies. The problem is worse during seasons when ocean water is warm and bacteria proliferate.
Drinking unpurified water is another of the primary causes of cholera, and probably the best known. Public wells and other water supplies are likely to become contaminated following wars or natural disasters. In 2010, an outbreak of cholera occurred in Haiti following an earthquake in January and flooding in later months. The inadequate sanitation and crowded living conditions that inevitably follow such catastrophic events put people at risk for the disease. Any water supply, however, may become contaminated if it is not protected from sewage.
One of the least discussed causes of cholera is normally healthful fruits and vegetables that become contaminated in the fields where they grow. In regions of the world where cholera is endemic, raw, unpeeled fruits and vegetables are a common source of infection. Developing nations may use manure fertilizers that have not gone through the composting process and may irrigate crops with water tainted by raw sewage. Such produce can be the source of a cholera outbreak.
Scientists and medical personnel understand the mechanism by which cholera kills; however, other people may not. V. cholerae, the bacteria that causes the disease, produces a powerful toxin that binds to the walls of the small intestine and disrupts the normal flow of sodium and chloride. The body begins to secrete huge amounts of water causing diarrhea so severe that it upsets the body’s electrolyte balance, which is essential for normal functioning of cells and organs. Untreated, cholera can cause death within hours.
