Declining Prevalence of Trichomonas vaginalis Diagnosed by Wet Mount in a Cohort of US Women With and Without HIV

Background: Women living with HIV (WLWH) are often coinfected with Trichomonas vaginalis (TV), and annual screening is recommended. Our goal was to assess differences in TV prevalence at study entry and over time in enrollment cohorts of the Women's Interagency HIV Study. Methods: In a multisite study, TV was diagnosed by wet mount microscopy. Prevalence was determined across four enrollment waves: 1994-1995, 2001-2002, 2011-2012, and 2013-2015. Generalized estimating equation multivariable logistic regression models assessed changes in visit prevalence across waves after controlling for HIV disease severity and other risks. Results: At 63,824 person-visits (3,508 WLWH and 1,262 women without HIV), TV was diagnosed by wet mount at 1979 visits (3.1%). After multivariable adjustment, HIV status was not associated with TV detection, which was more common among younger women, women with multiple partners, and irregular condom use. All enrollment waves showed a decline in TV detection over time, although p-value for trend did not reach significance for most recent waves. To explore the potential utility of screening among WLWH, we assessed rates of TV detection among women without appreciable vaginal discharge on examination. Initial TV prevalence among asymptomatic women was 3.5%, and prevalence decreased to 0.5%-1% in the most recent wave (2013-2015) (p-trend <0.0001). Conclusions: In this cohort, TV rates are low among WLWH, and HIV does not increase TV risk. Screening may benefit newly diagnosed WLWH, women with risk factors, or those receiving care sporadically but is unlikely to further reduce the low rate of TV among women in care, especially older women without multiple partners. The clinical trials registration number for WIHS is NCT00000797.