Hepatitis B in the rural tropics.

The prevalence of HBSAg in a cross-sectional serosurvey of a rural Thai village was nearly 8%. The corresponding antibody prevalence was approximately 35%. The prevalence of antigenaemia was significantly higher for adult males than for adult females. Possible dynamics of hepatitis B virus transmission in this rural village are explored, but tend to rely on a differential handling of antigenaemia by males and females. A considerable proportion of the hepatitis B virus exposure appears to be associated with malaria prophylaxis programmes.