BASE-LINE SEROEPIDEMIOLOGY OF HEPATITIS-B VIRUS-INFECTION IN CHILDREN AND TEENAGERS IN ITALY - A SURVEY BEFORE MASS HEPATITIS-B VACCINATION

During the period May 1987 to November 1989, the prevalence of hepatitis B virus (HBV) markers was determined by ELISA in serum samples of 7405 (55% male, 45% female) apparently healthy persons 3-19 years of age in Italy. Earlier studies of adults there had shown an intermediate degree of HBV endemicity (hepatitis B surface antigen carrier rate > 2%). Persons were selected by systematic cluster sampling in five different geographical areas of Italy. The overall prevalence of hepatitis B surface antigen (HBsAg) was 0·6 %. The overall prevalence of at least one marker of HBV was 2·8%; it increased from 1·7 % among children 3-5 years of age to 4·5 % in teenagers 17-19 years of age (P < 0·001). The prevalence of any HBV marker was higher in southern then in northern areas (3·5% vs. 1·8%, P < 0·001). A significant association was found with sociodemographic features. Persons whose fathers had less than 6 years of schooling had a 2·3-fold risk (C. I. 95% = 1·5-3·4) while those belonging to a household of six or more under one roof had a 1·7-fold risk (C. I. 95% = 1·2-2·4) of previous exposure to HBV infection. These findings indicate that, today in Italy, exposure to HBV infection at a young age is very low and suggest a shift towards a low degree of endemicity following improvements in socio-economic conditions, decreased family size and increasing use of disposable syringes during recent years. This survey, conducted before mass hepatitis B immunisation in Italy, provides up-to-date prevalence figures as reference data available for evaluating the effectiveness of future vaccination programmes. © 1991 The British Society for the Study of Infection.