Cholera is an infection in the small intestine caused by the bacterium Vibrio cholerae. The main symptoms are profuse, watery diarrhea and vomiting. Transmission occurs primarily by drinking water or eating food that has been contaminated by the feces of an infected person, including one with no apparent symptoms.
A person can get cholera by drinking water or eating food contaminated with the cholera bacterium. Large epidemics are often related to fecal contamination of water supplies or street vended foods. The disease is occasionally transmitted through eating raw or undercooked shellfish that are naturally contaminated.
Cholera is characterized in its most severe form by a sudden onset of acute watery diarrhoea that can lead to death by severe dehydration. The extremely short incubation period - two hours to five days - enhances the potentially explosive pattern of outbreaks, as the number of cases can rise very quickly.
About 75% of people infected with cholera do not develop any symptoms. However, the pathogens stay in their faeces for 7 to 14 days and are shed back into the environment, possibly infecting other individuals. Cholera is an extremely virulent disease that affects both children and adults. Unlike other diarrhoeal diseases, it can kill healthy adults within hours.
Modern sewage and water treatment have virtually eliminated cholera in industrialized countries. The last major outbreak in the United States occurred in 1911. But cholera is still present in Asia, the Middle East, Latin America, India and sub-Saharan Africa. The risk of cholera epidemic is highest when poverty, war or natural disasters force people to live in crowded conditions without adequate sanitation.
Approximately 5-10% of persons will have severe cholera which in the early stages includes: profuse watery diarrhea, sometimes described as “rice-water stools,” vomiting, rapid heart rate, loss of skin elasticity, dry mucous membranes, low blood pressure, thirst, muscle cramps, and restlessness or irritability. Persons with severe cholera can develop acute renal failure, severe electrolyte imbalances and coma. If untreated, severe dehydration can rapidly lead to shock and death.
Cholera is easily treated. Death results from severe dehydration that can be prevented with a simple and inexpensive rehydration solution.
Brackish and marine waters are a natural environment for the etiologic agents of cholera, Vibrio cholerae O1 or O139. There are no known animal hosts for Vibrio cholerae, however, the bacteria attach themselves easily to the chitin-containing shells of crabs, shrimps, and other shellfish, which can be a source for human infections when eaten raw or undercooked.
Large population migrations into urban centers in developing countries are straining existing water and sanitation infrastructure and increasing disease risk. Epidemics are a marker for poverty and lack of basic sanitation. Multiple routes of transmission mean that successful prevention may require different specific measures in different areas. Natural infection and currently available vaccines offer incomplete protection of relatively short duration; no multivalent vaccines are available for O139 infections.
Haiti dodged a bullet when Tropical Storm Tomas, once a hurricane, did minimal damage to the country's earthquake-ravaged capital of Port-au-Prince, where 1.5 million people are still homeless after the Jan. 12, 2010, cataclysm; in the outlying provinces, eight people were killed. But another storm, invisible to weather radar, may now be gaining strength: cholera.
Haiti has not had an outbreak of cholera in a century, and the source of the contamination remains a mystery. The CDC says that cholera in Haiti matches strains commonly found in South Asia. This news intensified concerns that a U.N. base housing Nepalese peacekeepers in Artibonite was the source.