INCIDENCE OF HEPATITIS A VIRUS-INFECTION AMONG AN ITALIAN MILITARY POPULATION

In 1990, a prospective serological survey to estimate the rate of clin ical and inapparent infection with hepatitis A virus (HAV) was perform ed in a cohort of 1,268 soldiers, 18-24 years old, during an 8 month p eriod in the Campania region in Italy. At the time of enrollment 318 ( 25%) of the 1,268 soldiers were positive for total antibodies to HAV ( anti-HAV). None of them was positive for IgM anti-HAV. Among the 950 s usceptible subjects who were followed up for 8 months, eight (0.8%) la ter seroconverted to anti-HAV positivity. This figure corresponds to a n incidence of 1.3/100 person/years (eight seroconversions during 633. 3 years of observation). There were two clinical (with presence of IgM -antiHAV) and six inapparent infections. The clinical/subclinical HAV ratio was 1:3. These findings indicate that the risk of HAV infection among soldiers residing in this area is not negligible.