Trichomonas vaginalis Incidence Associated with Hormonal Contraceptive Use and HIV Infection among Women in Rakai, Uganda.

Background. Data on the incidence of Trichomonas vaginalis and use of hormonal contraception (HC) are limited. Methods. 2,374 sexually active women aged 15-49 years from cohort surveys in Rakai, Uganda, were included. Incidence of T. vaginalis was estimated per 100 person years (py) and association between HC (DMPA, Norplant, and oral contraceptives) and T. vaginalis infection was assessed by incidence rate ratios (IRR), using Poisson regression models. Results. At baseline, 34.9% had used HC in the last 12 months, 12.8% HIV+, 39.7% with high BV-scores (7-10), and 3.1% syphilis positive. The 12-month incidence of T. vaginalis was 2.4/100 py; CI (1.90, 3.25). When stratified by type of HC used, compared to women who did not use HC or condoms, incidence of T. vaginalis was significantly higher among users of Norplant (adj.IRR = 3.01, CI: 1.07-8.49) and significantly lower among DMPA users (adj.IRR = 0.55, CI: 0.30, 0.98) and women who discontinued HC use at follow-up (adj.IRR = 0.30, CI: 0.09, 0.99). HIV infection was associated with an increase in incidence of T. vaginalis (adj.IRR = 2.34, CI: 1.44, 3.78). Conclusions. Use of Norplant and being HIV+ significantly increased the risk of T. vaginalis, while use of DMPA and discontinuation of overall HC use were associated with a decreased incidence of T. vaginalis.