Non-ulcerative sexually transmitted diseases as risk factors for HIV-1 transmission in women: results from a cohort study.

ABSTRACT

PIP: There is only a small probability that HIV-1 will be transmitted via any single sexual contact. The risk of transmission, however, during such an act may be greatly increased by the presence of ulcerative genital sexually transmitted disease (STD). Little evidence is published on whether infection with non-ulcerative STD facilitates the transmission of HIV-1. The authors therefore investigated whether treatable STD enhanced the sexual transmission of HIV-1 in a cohort of female prostitutes in Kinshasa, Zaire. 431 initially HIV-1-seronegative women were followed prospectively in this nested case-control study for a mean duration of two years in monthly STD check-ups and three-monthly HIV-1 serology. The 68 women who seroconverted were compared against the 126 women who remained HIV-1-seronegative for the incidence of STD and sexual exposure during the presumed period of HIV-1 acquisition. There was a 9.8% annual incidence of HIV-1 in this cohort of subjects. Seroconverters were of mean age 24.6 years compared to 26.8 years for the HIV-seronegative women. During the period of HIV-1 acquisition, cases had a much higher incidence of gonorrhea, chlamydial infection, and trichomoniasis, and engaged in unprotected sex with clients and partners more frequently than controls. After controlling for sexual exposure by multivariate analysis, adjusted odds ratio for seroconversion were 4.8 for gonorrhea, 3.6 for chlamydial infection, and 1.9 for trichomoniasis. Genital ulcers were more frequent in cases than controls, but much less common than other STD. These findings therefore suggest that non-ulcerative STDs were risk factors for the sexual transmission of HIV-1 in these women. Such STD may be a considerable population-attributable risk in the transmission of HIV-1 worldwide given the high prevalence of non-ulcerative STDs in some populations.