Hepatitis B surface antigen in menstrual blood and semen.

There is considerable epidemiologic evidence that hepatitis B surface antigen (HBsAg) may be transmitted sexually. With the reverse passive hemagglutination method, HBsAg was found in six (12%) of 50 male and four (8%) of 50 female Nigerians attending a family planning unit. HBsAg was detected in samples of semen in three (6%) male HBsAg carriers and in menstrual blood in four (8%) female carriers. Five (10%) women admitted to having sexual intercourse during menstruation. The presence of HBsAg in blood or semen does not appear to influence the sperm density or motility index. It is suggested that sexual intercourse may be one of the routines of HBsAg transmission in Nigeria.