Population-based survey of hepatitis A virus infection in the Republic of San Marino

In 1990–1991, the prevalence of antibodies to hepatitis A virus infection (anti-HAV) was assayed by the ELISA method among 1528 apparently healthy subjects, 20–85 years old in the Republic of San Marino. Subjects were selected from the list of residents by a random stratified sampling procedure with a proportional allocation by age, sex and district of residence. The overall anti-HAV prevalence was 64.7%; it increased from 28.6% in subjects 20–30 years old to 97% in those > 60 years (p < 0.01). No gender difference was observed. At the multivariate analysis age > 40 years (OR: 39.5; 95% CI: 12.4–126) and lowest level of schooling (OR: 1.8; 95% CI: 1.1–2.9), which is a good indirect indicator of socio-economic status, resulted both independent predictors of anti-HAV seroposi-tivity. These findings reflect the improved sanitation standards in this area and indicate that the proportion of non-immune adults is increasing with a higher risk of symptomatic infection in the near future.