A Study to Determine Susceptibility to Hepatitis A of Travelers from South Africa.

Hepatitis A is an important cause of acute hepatitis in travelers to developing countries. In 1991, 33 million persons living in industrialized countries traveled to developing countries where hepatitis A is highly endemic (World Tourism Organization, unpublished data, 1993). Reports indicate that 40-50% of cases of hepatitis A infection in the United Kingdom,1 Switzerland2 and Sweden3 are associated with recent international travel. The disease is usually benign, but the severity increases with age.4 Because the disease is enterically transmitted, occurrence is related to water quality and level of sanitation. In developing countries, with poor water quality and sanitation, especially in the tropics where hepatitis A is endemic, exposure is virtually universal before the age of 10 years.4 In developed countries with good food and water hygiene, the rate of exposure to hepatitis A in children is low. The rate of seropositivity increases slowly during early adulthood and reaches moderate levels during late adulthood.5 Studies have demonstrated the higher prevalence among people who live in poor, overcrowded conditions.6 Travelers going from low incidence countries to endemic areas are particularly at risk for acquiring hepatitis A, especially if they stay for extended periods.7 The risk that Danish travelers to North Africa would acquire hepatitis A was estimated to be 3.5 per 10,000, and this population accounted for at least 20% of all cases of hepatitis in Denmark. Similarly, Germans traveling or living in tropical countries have a 40 times higher risk of acquiring hepatitis than do groups living at home.8 The pattern in South Africans ranges from minimal exposure to hepatitis A in childhood in populations with good water quality and sanitation (mainly white), to high exposure in those exposed to poor water quality and sanitation in childhood (mainly black). Hepatitis A vaccine has been found to be effective in reducing the incidence of infection in travelers. After the introduction of hepatitis A vaccine into Switzerland in 1992, there has been a reduction by 15% in the cases of imported hepatitis A.9 Hepatitis A vaccine should be offered to South African travelers to high risk areas.10,11 However for the vaccine to be the most cost-effective, it would be important to identify groups of travelers who would benefit from empiric vaccination as opposed to other groups who should undergo screening prior to vaccination. This study was undertaken to establish the seroprevalence of hepatitis A in the South African traveler and to identify groups of travelers that should be vaccinated.