[Asymptomatic hepatitis B virus infection among the elderly].

The hepatitis B virus (HBV) infection usually occurs during infancy and children. To elucidate how the infection changes during the elderly life, 2233 residents were surveyed and among them 440 individuals with the age of 60-96 years were centered for analysis. The infection in the elderly was decreasing. HBsAg prevalence (5.0%) and titer (3.5 +/- 2.3) were getting lower, nearly all HBeAg seroconverted to anti-HBe, and the infection might be cleared at last. However, the HBV antibody prevalence steadily maintained, implying frequent HBV exposure and antibody responses during aging in the endemic area. Among them no fresh HBsAg were detected at one year follow-up, but antibodies developed in 10.8% of 65 individuals without HBV markers initially, and more, in 79 with single anti-HBs or anti-HBc 6.3% developed another antibody in a year. Therefore, the elderly population might be in a hypo-infection and dynamic hyperimmune status of the hepatitis B virus.