Australia antigen (HB Ag) in genitourinary secretions of Nigerians.

: HB Ag was determined in blood and urogenital fluids of Nigerians attending a clinic for sexually transmitted diseases. The antigen was found in 10 (5.43%) of 184 blood samples and in two of 72 urine samples. 189 samples of seminal fluid and vaginal secretions were negative. The antigenemia was similar to that reported in blood donors. The low frequency of the HB Ag in genito-urinary secretions may be due to intermittent excretion. Sexual intercourse may not be an important route of transmission in Nigeria.