Background Screening for C. trachomatis in the U.S. is recommended among women 25 years of age and younger. T. vaginalis (TV) is not a reportable disease, but has been associated with increased risk of other STIs. National prevalence data suggest that TV is common among African American women and increases with increasing age among women (Sutton et al. 2007). The local epidemiology of TV is not well understood.

Methods We compare population and subpopulation estimates of Ct and TV infections among a probability sample of 15 to 35-year olds residing in Baltimore, MD, an urban area with high rates of STIs. The Monitoring STIs Survey Program (MSSP) collected survey data and urine specimens for STI testing from 2,120 participants in 2006–09.

Results The overall estimated prevalence of T. vaginalis was 7.5% (95% CI 6.0, 9.0); infection was significantly higher among women (11.8%) than men (2.9%, OR = 5.1, 95% CI 2.0, 13.0). Over 75% of infections were asymptomatic. Among Black females, the estimated prevalence was 16.1% (95% CI 12.8.19.5). Contrary to national estimates, rates of infection were significantly higher among subjects less than 26 years of age (8.8% v 5.9%, p = 0.04). In contrast, chlamydial infection was less prevalent overall, 3.9% (95% CI 2.9, 5.2), and higher among men (4.5%, 95% CI 2.8, 6.9) than women (3.4%, 95% CI 2.4, 4.8). Estimates of CT infection decreased with increasing age (p < 0.001). Nearly one-quarter of CT infections (23.5%) were also positive for TV.

Conclusion These data suggest a high burden of TV and co-infection with CT. Public health surveillance focusing on CT infection may consider routine screening of other STIs, including TV, in local populations to reduce STI morbidity.