Hepatitis A virus infection in the United States: serologic results from the Third National Health and Nutrition Examination Survey.

To determine the prevalence of hepatitis A virus (HAV) infection in the general U.S. population, sera from participants in the Third National Health and Nutrition Examination Survey (NHANES III) conducted in 1988-1994 were tested for antibody to HAV (anti-HAV). Among 21,260 participants aged > or = 6 years tested, the overall prevalence of infection was 31.3%, and increased markedly with age. The age-adjusted prevalence was significantly higher among foreign- compared to U.S.-born participants, and was highest among Mexican-Americans and lowest among non-Hispanic whites. Among U.S.-born children, only Mexican-American ethnicity and income below the poverty level were associated with HAV infection in a multivariate model. During this period before hepatitis A vaccination, age, ethnicity and birthplace were the most important determinants of HAV infection in the United States.