Cholera

In the United States, sewage treatment and water purification plants are ubiquitous, and consequently, the incidence of cholera is low. Almost all cases of cholera in the U.S. are caused by improperly cooked shellfish. Experts recommend that all shellfish be boiled for 10 minutes; steaming does not kill V. cholerae. Raw shellfish should be avoided.

Another way to prevent cholera is to identify and treat cholera carriers in areas where cholera is endemic. Treating carriers would eliminate a major route of cholera transmission.

Currently, several cholera vaccines are being developed, but only one is likely to be effective. Injectable vaccines are impractical in many areas. Oral vaccines are more easily delivered to the population, but are not nearly as effective. A genetically engineered vaccine that consists of an altered V. cholerae organism appears to stimulate an immune response in a small number of volunteers. Larger vaccine trials in endemic populations are necessary, however, to determine the efficacy of this vaccine. Currently available vaccines confer only partial, short-term immunity, and therefore are not being recommended for most travelers. Instead, preventive measures are advised. For cholera endemic areas, suggestions include drinking only boiled or chlorine- or iodine-treated water; avoiding ice; avoiding fruits and vegetables unless cooked thoroughly or peeled; eating only very thoroughly cooked seafood.