Incidence Rates of Hepatitis B and C Virus Infections among Blood Donors in Hiroshima, Japan, during 10 Years from 1994 to 2004

Abstract

Objective: Although prevalence rates of hepatitis B virus (HBV) and hepatitis C virus (HCV) infections have kept decreasing in blood donors, there is little information on incidence rates of these hepatitis viruses in Japan. Methods: During 10 years from June 1994 through April 2004, 418,269 inhabitants of Hiroshima, Japan, donated blood (1,409,465 units in total). They were screened for serum markers of HBV and HCV infections, and individuals who developed de novo infections were identified. Results: Infection with HBV occurred at a rate of 2.78 per 100,000 person-years (95% confidence interval: 1.78–4.14/100,000 person-years) and that with HCV at a rate of 1.86 per 100,000 person-years (95% confidence interval: 1.06–3.01/100,000 person-years). Residual risks of transmission by transfusions, based on the relationship risk [window period (estimated at 0.15 and 0.03 years in chimpanzees inoculated with minimum infectious doses for HBV and HCV, respectively) × incidence], were 1/243,000 for HBV and 1/1,960,000 for HCV infections. Conclusion: At present, incidence rates of HBV and HCV infections are extremely low in Japan.