Cholera

Description

Cholera is an acute intestinal infection caused by toxigenic Vibrio cholerae O-group 1 or O-group 139. The infection is often mild and self limited or subclinical. Patients with severe cases respond dramatically to simple fluid- and electrolyte-replacement therapy. Infection is acquired primarily by ingesting contaminated water or food; person-to-person transmission is rare.

Occurrence

Since 1961, V. cholerae has spread from Indonesia through most of Asia into Eastern Europe and Africa, and from North Africa to the Iberian Peninsula. In 1991, an extensive epidemic began in Peru and spread to neighboring countries in the Western Hemisphere. In 2003, 111,575 cases from 45 countries were reported to the WHO.

Risk for Travellers

Travellers who follow usual tourist itineraries and who observe food safety recommendations while in countries reporting cholera have virtually no risk. Risk increases for those who drink untreated water or eat poorly cooked or raw seafood in disease-endemic areas.

Prevention

Vaccine

The risk of cholera to U.S. travellers is so low that vaccination is of questionable benefit. The manufacture and sale of the only cholera vaccine licensed in the United States (by Wyeth Ayerst) have been discontinued. The vaccine is not recommended for travellers because of the brief and incomplete immunity it confers.

Two recently developed oral vaccines for cholera are licensed and available in other countries (Dukoral from Biotec AB and Mutacol from Berna). Both vaccines appear to provide somewhat better immunity and have fewer adverse effects than the previously available vaccine. However, CDC does not recommend either of these two vaccines for most travellers, nor are they available in the United States. Further information on these vaccines can be obtained from the manufacturers: Dukoral, Active Biotec AB, P.O. Box 724, SE-220 07, Lund, Sweden; telephone: 46 46 19 20 00; fax: 46 46 19 20 50; e-mail: info@activebiotech.com; and website: http://www.activebiotech.com; and Mutacol, Berna, Switzerland Division, P.O. Box CH-3001, Bern, Switzerland; telephone: 41 31 981 22 11; fax: 41 31 981 20 66. E-mail information is available at http://www.bernaproducts.com/contact.cfm and from the website http://www.bernaproducts.com.

Currently, no country or territory requires vaccination against cholera as a condition for entry. Local authorities, however, may continue to require documentation of this vaccination. In such cases, a single dose of either oral vaccine is sufficient to satisfy local requirements, or the traveller may request a medical waiver from a physician.

Other

Travellers to cholera-affected areas should be advised to avoid eating high-risk foods, especially fish and shellfish. Food that is cooked and served hot, fruits and vegetables peeled by the traveller personally, beverages and ice that are made from boiled or chlorinated water, or carbonated beverages are usually safe. (See Risks from Food and Water, for additional information.) Chemoprophylaxis is almost never indicated.

Treatment

Rehydration is the cornerstone of therapy for cholera; antibiotics are an adjunct useful in severe cases only. Oral rehydration salts, and when necessary intravenous fluids and electrolytes, if administered in a timely manner and in adequate volumes, will reduce case-fatality rates to well under 1%.

Bibliography
  • Cholera, 2003. Weekly Epidemiologic Record. 2004;31:281-8.
  • Steinberg EB, Greene KD, Bopp CA, Cameron DN, Wells JG, Mintz ED. Cholera in the United States, 1995-2000: trends at the end of the milennium. J Infect Dis. 2001;184:799-802.
  • World Health Organization. Guidelines for cholera control. Geneva, Switzerland: World Health Organization; 1993.

- Eric Mintz

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