Trichomonas vaginalis infection and human immunodeficiency virus acquisition in African women.

BACKGROUND: Trichomoniasis vaginalis is the most common nonviral sexually transmitted infection (STI) worldwide, with a particularly high prevalence in regions of human immunodeficiency virus (HIV) endemicity. However, its impact as a cofactor for HIV acquisition is poorly understood.
METHODS: Samples from 213 women who experienced HIV seroconversion (cases) during a longitudinal study involving 4450 women in Uganda and Zimbabwe were matched with samples from HIV-uninfected women (controls). All samples underwent polymerase chain reaction (PCR) analysis for Trichomonas vaginalis DNA. For cases, analyzed samples were from the visit in which HIV seroconversion was detected and the visit preceding detection of seroconversion; for controls, one analyzed sample was from the visit matched by follow-up duration to the cases' seroconversion visit, and the other sample was from the visit immediately preceding the matched visit.
RESULTS: The prevalence of T. vaginalis infection before HIV infection was 11.3% in cases and 4.5% in controls (P = .002). In multivariable analysis controlling for hormonal contraception, other STIs, behavioral, and demographic factors, the adjusted odds ratio for HIV acquisition was 2.74 (95% confidence interval, 1.25-6.00) for T. vaginalis-positive cases. The presence of behavioral risk factors for HIV infection, study recruitment from a referral population at high-risk for HIV, primary sex partner-associated risk for HIV infection, and herpes simplex virus type 2 seropositivity were also predictive of incident HIV infection.
CONCLUSIONS: T. vaginalis infection is strongly associated with an increased risk for HIV infection in this general population of African women. Given the high prevalence of T. vaginalis infection in HIV-endemic areas, T. vaginalis control may have a substantial impact on preventing HIV acquisition among women.