HBV exposure and HBsAg positivity rates in schistosomiasis japonica: study in a Philippine community endemic for both infections.

HBV exposure and HBsAg positivity rate were examined in 561 residents of an area endemic for S. japonicum and 22 additional cases with severe HSS japonica were also included. The differences in HBV exposure and HBsAg positivity rates among the groups without the parasitism, with schistosomiasis japonica and with HSS (53 cases) were not statistically significant. Comparison of the same parameters between those with and without S. japonicum infection according to sex and age groupings did not also show significant differences. Increasing intensity of S. japonicum infection was not associated with either increasing or decreasing HBV exposure and HBsAg positivity. It is postulated that HBV infection does not contribute to the production of HSS japonica mainly because HBV infection occurs at a much earlier age than S. japonicum infection.