Background Trichomonas vaginalis (TV) is the most common curable sexually transmitted infection (STI) worldwide. Trichomonas vaginalis infection is associated with an increased risk of pelvic inflammatory disease, human immunodeficiency virus transmission, and preterm birth in women. Data on the prevalence and risk factors for TV infection in sub-Saharan African countries remain scarce. Methods A total of 350 Kenyan female sex workers, aged 18 to 50 years, participated in a 2-year longitudinal study of the acquisition of STIs, including TV infection. Every 3 months, cervical and vaginal brush samples were collected for STI testing. At baseline, a sociodemographic and behavior questionnaire was administered. Testing for TV, Chlamydia trachomatis (CT), Neisseria gonorrhoeae, Mycoplasma genitalium, and high-risk human papillomavirus was performed using APTIMA assays. Results The TV baseline prevalence was 9.2% (95% confidence interval [95% CI], 6.3-12.7%) and 2-year cumulative TV incidence was 8.1 per 1000 person months (6.9-9.3). Risk factors for higher TV prevalence at baseline were CT infection (adjusted prevalence ratio [PR], 8.53; 95% CI, 3.35-21.71), human immunodeficiency virus seropositivity (PR, 3.01; 95% CI, 1.45, 6.24) and greater than 4 years of sex work (PR, 2.66; 95% CI, 1.07-6.60). Risk factors for elevated 2-year TV incidence were CT (hazard ratio [HR], 4.28; 95% CI, 1.36-13.50), high-risk human papillomavirus infection (HR, 1.91; 95% CI, 1.06-3.45) and history of smoking (HR, 2.66; 95% CI, 1.24-5.73). Discussion CT infection was positively associated with both prevalent and 2-year incident TV infections.
