Age-specific prevalence of hepatitis A virus infection among teenagers in Sardinia.

In 1989, the prevalence of antibodies to hepatitis A virus (anti-HAV) in a sample of 1350 Sardinian teenagers aged 14 to 19 years was estimated by Elisa method. The overall anti-HAV prevalence was 20%; it increased from 12.3% among 14-16 year old subjects to 27.4% in subjects aged 17-19 years (P less than 0.01). A slight female preponderance was observed (22.1% versus 17.9) but no statistically significant difference was attained. Compared with the corresponding figure (71.6% of prevalence rate) observed in North Sardinia in 1980, the results of the present study show a dramatic reduction in anti-HAV prevalence among teenagers. A significant association was found with sociodemographic factors: subjects whose fathers had less than six years of schooling, had a 2.1-fold risk (C.I. 95% = 1.5-3.1) and subjects belonging to a household of 6 or more under one roof had a 1.7-fold risk (C.I. 95% = 1.2-2.3) of previous exposure to hepatitis A virus (HAV) infection. These findings indicate that exposure to HAV in Sardinia is decreasing, probably because of improvements in socio-economic conditions during recent years. However, overcrowding and short paternal education appear to be important determinants of infection.