On Cholera Worldwide

November 1, 2010

Though the last major outbreak in the United States occurred in 1911, cholera remains a persistent health concern in many parts of the world, including Asia, the Middle East, Latin America, and sub-Saharan Africa. Recent outbreaks have been seen in Nigeria,  where cholera has killed more than 1,500 people this year, and in Haiti, where survivors of the massive January earthquake have been affected by an outbreak that has infected an estimated 2,300 people and killed at least 200. Due to cholera, there are an estimated three to five million new cases reported worldwide and between 100,000 and 120,000 deaths each year. Like other diarrheal illnesses, cholera is easily treatable and can be prevented through the provision of safe water, improved sanitation services, and education about the importance of hygiene.

Cholera

Cholera is an acute diarrheal infection caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae. Though three-quarters of individuals infected with V. cholerae do not exhibit any symptoms, they may shed the bacteria in their stool for seven to 14 days, potentially infecting others. While V. cholerae is the direct source of cholera infection, the deadly effects of the disease are caused by a toxin called CTX, that the bacteria produce in the small intestine of the host. CTX binds to the intestinal walls and interferes with the normal flow of sodium and chloride, causing the body to secrete large amounts of water and leading to diarrhea accompanied by dehydration. In individuals exhibiting the severe form of the disease, the rapid loss of fluids can lead to dehydration and shock, and without treatment death can occur within hours. Approximately one in 20 individuals infected with the bacteria develops symptoms associated with cholera, which include: severe, watery diarrhea; nausea and vomiting; muscle cramps; dehydration; and shock.

The rapid loss of fluids in a short period of time – often as much as a quart in an hour – associated with diarrhea due to cholera, makes the disease particularly deadly. In order to replenish the fluids and electrolytes that an individual with severe cholera has lost, Oral Rehydration Salts (ORS) must be administered. If a pre-formulated solution is not available, experts suggest combining one-half teaspoon salt, one-half teaspoon baking soda, and three tablespoons sugar in one liter of safe drinking water. With the prompt delivery of ORS, up to 80 percent of people can be treated successfully, with a fatality rate below one percent. Antibiotics may be used in conjunction with ORS to shorten the course and lessen the severity of the illness, however their delivery is less critical to cholera patients than rehydration. To help control the spread of the disease, two types of oral cholera vaccines are also available, but according to experts they provide only a short-term effect and should be administered in areas where ongoing water and sanitation improvement programs are in place.

Despite the simplicity of the cure, thousands of people die each year in regions that lack effective sanitation and water purification systems. Following man-made or natural disasters, the risk of an initial outbreak of cholera growing into an epidemic is greatly increased. As seen recently following floods in Pakistan and Nigeria, the spread of cholera becomes a major public health concern when there is a lack of clean water. By providing treatment as well as information about the importance of boiling water before drinking and maintaining personal hygiene, it may be possible to slow or even stop the spread of cholera and other communicable diseases.

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