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While a safe water source is important to prevent the transmission of cholera, a recent outbreak in the Marshall Islands shows that handling and storing the water safely is also critical.
Cholera, an infectious disease that produces severe diarrhea, is caused by a microbe that can contaminate water supplies. Although adding chlorine to the water can kill the microorganism, in the current study, the outbreak occurred despite the use of this cleansing measure.
In December 2000, the first known outbreak of cholera in the Republic of the Marshall Islands was reported on Ebeye Island. A new study of the outbreak, reported in the medical journal Clinical Infectious Diseases, focuses on 53 patients with cholera and 104 similar subjects without the disease.
In tracking down the source of the outbreak, Dr. Mark E. Beatty, from the Centers for Disease Control and Prevention in Atlanta, and colleagues found that cholera patients were eight times more likely than unaffected people to have drunk water that was transported to Ebeye from a U.S. military installation on a nearby island.
Interestingly, the military water came from a chlorinated source that was considered to be safe from cholera contamination. Moreover, none of the residents on the island where the water originated developed cholera. These findings led researchers to consider that contamination occurred while the water was being sent to Ebeye.
In support of this hypothesis, the authors found that drinking water transported in a cooler with a tight-fitting lid reduced the risk of cholera infection, presumably because the secure seal slowed the loss of chlorine that occurs with evaporation. Other factors tied to a reduced risk of infection included drinking bottled water, boiled water, or water mixed with powdered flavorings.
"Providing a safe water source can be insufficient to prevent cholera transmission if the means for safe transport and storage of water are not available," the investigators emphasize.