Hepatitis A and the American traveler.

Morbidity from hepatitis A in American travelers may be greater than currently recorded. Risks for acquiring hepatitis A are widespread in developing countries, and a single lapse from appropriate hygiene for food or water is sufficient to cause infection. In Peace Corps personnel, a strictly regulated policy of immune serum globulin (ISG) at 4-month intervals reduced the rate of hepatitis A to 0.1-0.3 cases (from 1.6-2.1 cases)/100 persons/year. Data from United States Foreign Service personnel, for whom there is no mandated ISG policy, show hepatitis A to be the most commonly reported immunization-preventable infection; rates are 0.06-0.16/100 person-years, depending on the area of the world. With the availability of a hepatitis A vaccine, frequent travelers or those who stay long-term in hepatitis-endemic areas can attain higher antibody concentrations and much longer protection than is currently available from ISG.