Decrease of hepatitis A and B virus infections in the population of Okinawa, Japan.

In 1988 1282 serum samples were collected from healthy Japanese persons living on Hateruma Island (574 samples) and Iriomote Island (708 samples) in Okinawa, Japan. Serological markers of hepatitis B virus (HBV) infection [hepatitis B surface antigen (HBsAg), antibody to hepatitis B core antigen (anti-HBc) were investigated and the findings compared with samples taken in 1980 on Hateruma Island and in 1970 and 1980 on Iriomote Island. The samples collected in 1988 on Iriomote Island were also tested for antibody to hepatitis A virus (anti-HAV) and the findings compared with the results of the 1970 and 1980 surveys. The overall prevalence of HBsAg and anti-HBc was 3.7 and 64.8% for Hateruma Island and 3.8 and 44.9% for Iriomote Island. In both areas the overall prevalence of anti-HBc was lower than in 1980, the decrease being significant for the 10-19 year age group on Hateruma Island and the age groups under 39 years on Iriomote Island. The overall prevalence of anti-HAV had fallen to 50.9%. This remarkable decrease had occurred in children and young adults. These data suggest that Virus A (HAV) and HBV infections have dramatically decreased among children in Okinawa within the past 2 decades.