Background:
Trichomoniasis is the most common non-viral STD and may be associated with adverse birth outcomes and increased susceptibility or transmissibility of HIV. This study is one of the first to analyze risk factors associated with incident infections.

Objective:
The objectives are to describe the epidemiology of trichomoniasis in STD clinics and characterize the risk factors for prevalent and incident infections.

Method:
We analyzed data from 1999-2001 from three STD clinics in Newark, NJ, Long Beach, CA, and Denver, CO. Data were analyzed from 1462 women aged 15-39 years who were tested by wet mount or culture at their initial visit for T. vaginalis, and for 1269 women with at least one follow-up visit. Risk factors for prevalent infections at baseline and incident infections among treated or previously uninfected women, followed for one year at quarterly visits, were assessed.

Result:
At baseline, 13% had a prevalent infection; risk factors included: Ан35 vs. <20 years (OR=2.6, 95% CI 1.4-4.8), black race (OR=3.2, 95% CI 2.3-4.6), <12 years of education (OR=1.6, 95% CI 1.1-2.3), chlamydia at the current visit (OR=2.3, 95% CI 1.5-3.4). At follow-up, 13% of women had an incident infection; risk factors included: Ан35 vs. <20 years (OR=3.0, 95% CI 1.5-6.2 ), black race (OR=4.8, 95% CI 3.0-7.7), having <12 years of education (OR=1.9, 95% CI 1.2-3.0), ever exchanging sex for drugs/money (OR=2.6, 95% CI 1.1-6.3), symptoms (OR=2.4, 95% CI 1.5-3.8), chlamydia at the current visit (OR=4.1, 95% CI 1.9-8.9), and having had Ан2 sexual partners in the past 3 months (OR=2.3, 95% CI 1.5-3.6).

Conclusion:
Trichomoniasis is high in all women. Risk factors for prevalent and incident infection are similar. Trichomoniasis was associated with older age in women, unlike other STDs.

Implications:
Screening for trichomoniasis should be considered as an STD prevention approach for women in STD clinics.