RESUMO
BACKGROUND: The level of endemicity and modes of transmission of hepatitis B virus infection may change over time. AIMS: To assess prevalence of and risk factors for hepatitis B infection in the general population. SUBJECTS: A total of 1352 subjects residing in a Southern Italian town in the year 1996. METHODS: Subjects were selected from the census by a systematic 1:4 random sampling procedure. Hepatitis B surface antigen and antibodies to hepatitis B core antigen were detected by ELISA. The association (Odds Ratio) linking hepatitis B seropositivity to potential risk factors was estimated by univariate and multivariate analysis. RESULTS: The participation rate was 96.6%. The overall prevalence of hepatitis B surface antigen and antibodies to hepatitis B core antigen were 0.8% and 21.5%, respectively. Hepatitis B surface antigen prevalence was 0.2% in subjects younger than 30 years, peaked to 2.5% in the age-group 40-49 years, and decreased to 0.3% in those 60 years and older. Antibodies to hepatitis B core antigen positivity linearly increased from 6.2% in subjects < 30 years of age to 37.1% in those 60 years or older (p < 0.01). The results of multiple logistic regression analysis showed that age > 45 years (Odds Ratio = 1.9; Confidence Intervals 95% = 1.2-3.0), use of glass syringes (Odds Ratio = 2.2; Confidence Intervals 95% = 1.5-3.4), surgical intervention (Odds Ratios = 1.8; Confidence Intervals: 95% = 1.3-2.6), and positivity for antibodies to hepatitis C virus infection (Odds Ratios = 2.6; Confidence Intervals 95% = 1.5-4.3) were all independent predictors of the likelihood of hepatitis B positivity. CONCLUSIONS: Given that a significant proportion of the general population undergoes surgical intervention, the association found between hepatitis B positivity and this exposure highlights the importance of further developing efficient procedures for the sterilization of instruments as well as the use of disposable materials to control the spread of infection.