Trichomonas vaginalis is the causative agent of trichomoniasis. It accounts for 4 to 35 percent of vaginitis diagnosed in symptomatic women presenting in primary care settings.
The prevalence of trichomonas vaginalis infection in reproductive aged women in the US was best illustrated by a study in which 3754 women aged 14 to 49 years self-collected vaginal swab specimens that were subsequently evaluated for the presence of T. vaginalis using PCR. The overall prevalence of T. vaginalis was 3.1 percent, and increased with age. Prevalence was highest in non-Hispanic black women (13.3 percent) and lowest in non-Hispanic white women (1.3 percent). The annual incidence in the United States has been estimated to be three to five million cases.