Epidemiology of hepatitis A and hepatitis E infection and their determinants in adult Chinese community in Hong Kong

Current epidemiology of hepatitis A virus (HAV) and hepatitis E virus (HEV) in Hong Kong was evaluated in 936 adult Chinese subjects recruited through a telephone interview in 2001. Some 15% of the subjects had IgG antibodies to both HAV and HEV while 665 (71.0%) and 176 (18.8%) had anti-HAV and anti-HEV, respectively. Age was the most significant independent factor. Six hundred thirty-eight (79.8%) and 165 (20.7%) subjects aged >30 had anti-HAV and anti-HEV, respectively, as compared with 27 (19.7%) and 11 (8.0%) in people aged <30. The corresponding adjusted Odds ratio (OR) was 14.94 (95% CI: 9.13-24.44; P < 0.001) for anti-HAV positivity and 2.99 (95% CI: 1.58-5.67; P = 0.001) for anti-HEV positivity. Subjects born outside Hong Kong were more likely to have anti-HAV (adjusted OR: 3.41; 95% CI: 2.21-5.26; P < 0.001) but not anti-HEV. Non-labour work people were less likely to have anti-HAV-adjusted OR, 0.40 (95% CI: 0.26-0.62; P < 0.001). Age-specific HAV prevalence right shifted in the last 20 years. Anti-HAV positivity was less frequent, across all age groups, in subjects >21-years-old in the present study than another study done in 1987-89 (P < 0.001). HAV prevalence only increased slightly in every 10-year age groups of people aged 21-50 when compared with their corresponding 10-year-younger age groups (P = 0.11), suggesting an ageing cohort effect with no major infections in the last decade. For HEV, both the overall and age-specific prevalence decreased over the last decade (P < 0.001). The increasing proportion of susceptible population to enterically transmitted viral hepatitis has implications to future prevention and control programmes, including vaccination strategies. (C) 2004 Wiley-Liss, Inc.