Baseline seroepidemiology of hepatitis A virus infection among children and teenagers in Italy.

During the period from May 1987 through November 1989, the prevalence of antibodies to hepatitis A virus infection (anti-HAV) was assayed by the ELISA method in the serum samples of 5,507 (54% males, 46% females) apparently healthy subjects three to 19 years old in Italy. Subjects were selected by a systematic cluster sampling in five different geographical areas of Italy. The overall prevalence of anti-HAV was 9.5%; it increased from 2.3% among children three to five-years-old to 16.3% in teenagers 17 to 19 years old (p less than 0.001). A slight preponderance of females was observed (10% versus 9.1%), but the difference was not statistically significant. The prevalence was significantly higher in Southern Italy than in Northern Italy (27.4% versus 4.8%; p less than 0.01). The prevalence of anti-HAV was inversely related to the fathers' years of schooling (O.R. 3.3; 95% C.I. = 2.5-4.2) and positively related to the family size (O.R. 2.4; 95% C.I. = 1.9-3.1). These findings indicate that, today, exposure to HAV infection at a young age in Italy is very low. However, sociodemographic factors are still important determinants in the spread of this infection.