Search

To investigate HBV transmission in families on three islands in Okinawa, Japan, prevalence of HBV markers in two groups of inhabitants was determined. One group consisted of members of families in which there was at least one HBsAg carrier (carrier families); the other group consisted of members of families in which there were no HBsAg carriers (non-carrier families). A total of 3,261 serum samples were collected from subjects on Iriomote Island, Hateruma Island, and Yonaguni Island. These samples were tested for HBsAg by reversed passive hemagglutination (RPHA) and for antibody to hepatitis B core antigen (anti-HBc) by radioimmunoassay. Overall prevalences of HBsAg and anti-HBc were 8.2 and 65.8 per cent respectively. The prevalence of anti-HBC among members of carrier families (80.8%) was significantly higher than that among members of non-carrier families (61.6%) (P less than 0.001). The prevalence of anti-HBc among members of carrier families was higher in all age groups, and was particularly so in children. Within carrier families, the prevalence of anti-HBc was significantly higher in families in which there was at least one HBsAg carrier with HBeAg (94.5%) than in families with no HBeAg-positive carriers (76.1%). This difference was especially marked in young children. These data suggest that in families with HBsAg carrier(s), the risk of transmitting HBV to members, particularly to young children, is higher than in families without carriers, and that the risk is further increased in families with HBeAg-positive carrier(s).

Two separate studies were carried out between 1968 and 1984; a total of 2,021 serum samples from healthy subjects were collected in two districts of Okinawa-on Iriomote Island and in Ishigaki City. The first samples were collected in 1970 on Iriomote Island and in 1968 in Ishigaki City. The second samples were collected after an interval of 13 years in Ishigaki City and after an interval of 15 years on Iriomote Island. These serum samples were tested for the presence of antibody to adult T-cell leukemia-associated antigen (anti-ATLA). The overall prevalence of anti-ATLA in both areas combined was 9.9% from 1968 to 1970 and that from 1981 to 1984 was 8.9%. At both times, anti-ATLA prevalence increased with age and was higher in females than in males. No significant changes in anti-ATLA prevalence was observed: after intervals of 13 and 15 years, the prevalence decreased from 10.2 to 9.9% in Ishigaki City and from 9.4 to 8.2% on Iriomote Island. These data suggest that there has been no significant change in the rate of infection with adult T-cell leukemia virus in recent years in the areas studied.