According to the results of research published in the American Journal of Obstetrics & Gynecology, the prevalence of Trichomonas vaginalis was highest in women aged 47 to 53 years, whereas the prevalence of Chlamydia trachomatis was highest at ages 14 to 20 years.
In this retrospective study, 1,554,966 and 1,999,077 cervicovaginal samples obtained from women aged 10 to 79 years were analyzed for T vaginalis and C trachomatis, respectively. Analyses were performed with quantitative real-time polymerase chain reactions.
The association between positivity rates for each pathogen and age or US state were evaluated. T vaginalis positivity rates had a bimodal distribution for age, with peaks at 22 years (4.1%) and 48 years (5.8%).
In samples from women between the ages of 49 and 53 years, the prevalence of T vaginalis remained higher than 5%, and between 54 and 60 years, the prevalence was higher than 4%. C trachomatis positivity rates were normally distributed between the ages of 10 years (≤0.9%) and 27 years (2.0%), with a peak of 8.6% at 17 years. Between the ages of 47 to 79 years, the positivity rate was ≤0.3%.
The US states with the highest rates of T vaginalis positivity were Mississippi (9.0%), Wisconsin (7.8%), and South Carolina (7.4%). In contrast, the states with the highest rates of C trachomatis were Maine (6.4%), South Dakota (4.6%), and Louisiana (4.3%).
A total of 1.5% of T vaginalis-positive specimens had the ntr6TV polymorphism, which is correlated with metronidazole resistance. No association between age and the presence of the polymorphism was found.
David Hilbert, senior author on the study, explained that the results are important because "screening is not performed for T vaginalis, so there may be a substantial population of older women carrying this pathogen who are unaware and unintentionally spreading it to sex partners." He concluded that "testing older women who might not be suspected of harboring a sexually transmitted infection for T vaginalis may be a good idea."