Sexual transmission of hepatitis B in Mwanza, Tanzania.

ABSTRACT

PIP: To investigate the role of sexual transmission of hepatitis B virus (HBV) in East Africa, a cross-sectional serosurvey was conducted in 3 populations with potentially divergent exposure to sexually acquired pathogens. Included were 253 voluntary blood donors (predominantly secondary school students), 952 relative blood donors, and 1025 patients with sexually transmitted diseases (STDs) from Mwanza, Tanzania. The overall prevalence of hepatitis B surface antigen (HBsAg)--a measure of current infection--was 9.9% in voluntary donors, 11.2% in relative donors, and 8.1% in STD patients, with a 2.2:1 carrier ratio of men to women. The prevalences of human immunodeficiency virus (HIV), anti-hepatitis B core antigen (anti-HBc), and past or recent syphilis were significantly lower among voluntary donors than in the other 2 groups. Evidence of past infection with HBV (anti-HBc) was associated with recent syphilis in both men and women (odds ratios (ORs), 1.91 and 2.34, respectively) and with HIV in men (OR, 1.93). Current infection with HBV (HBsAg) was associated with recent syphilis in men (OR, 2.13). In STD patients, current HBV was associated with Trichomonas vaginalis in women (OR, 3.57) and recent syphilis in men (OR, 3.46). There was no significant association between HBV and gonorrhea. Based on the association between syphilis and HBV, the population attributable fraction for sexual acquisition of HBV is estimated at 7.2% in men and 3.0% in women. Overall, these findings suggest that the sexual acquisition of HBV occurs at low levels in Mwanza. Improved vaccination strategies, early detection and treatment of syphilis, and programs aimed at reducing HIV transmission should enhance the control of HBV.