Long-term epidemiological survey of hepatitis B virus infection in a hyperendemic area (Afragola, southern Italy): results of a pilot vaccination project.

In 1983, a pilot project of universal hepatitis B vaccination was introduced in a hyperendemic area in southern Italy (Afragola) and is ongoing to date. In this area before the start of vaccination, we found significant evidence of HBV endemicity: the acute viral hepatitis B incidence in the general population averaged 63/100,000; the HBsAg and anti-HBc prevalence rates were 13.4% and 66.9%, respectively; there was involvement of hepatitis B virus (HBV) in 48.1% of chronic liver pathologies (46.3%) in chronic viral hepatitis, 49.5% in cirrhosis and 71.7% in hepatocellular carcinoma cases). We studied the acute viral hepatitis incidence during the vaccination period from 1983 to 1997 and compared the HBsAg and anti-HBc prevalences in 1978 to those in 1997, after 15 years of vaccination. The HBV-related chronic pathology prevalence was also studied. We found a remarkable drop in the acute viral hepatitis incidence, from an average annually of 63/100,000 in the five years before vaccination to 3/100,000 in the last five years of vaccination. In addition, the HBsAg carrier prevalence in the general population decreased from 13.4% in 1978 to 3.7% in 1997. The percentage dropped in children and adolescents from 6.8% to 0.7%, in young people from 10.2% to 1.1% and in adults from 15.8% to 4.0%. The anti-HBc carrier prevalence, found to be 66.9% in 1978, was 34.2% in 1997. Finally, we found a much less significant involvement of HBV in chronic liver pathologies; in fact, it was present in only 18.2% of cases in 1997 and in 48.2% in 1982. In the light of the data, we can assert that universal hepatitis B vaccination has had a substantial effect on HBV endemicity in the Afragola area. We believe that the reduction found in the incidence of acute viral hepatitis B and HBV-related chronic liver pathologies is connected to the decrease in HBV carriers in the area, which therefore reduces the risk of contagion for the unvaccinated.