Incidence rates of hepatitis B and C virus infections among blood donors in Hiroshima, Japan, during 10 years from 1994 to 2004

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) x 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. Copyright (c) 2008 S. Karger AG, Basel.