Incidence and Prevalence of Trichomonas vaginalis Infection Among Persons Aged 15 to 59 Years: United States, 2018

Abstract

Background: Trichomonas vaginalis (TV) is a sexually transmitted parasite associated with multiple adverse outcomes in women. Estimating TV incidence is challenging because of its largely asymptomatic presentation.Methods: Per-capita prevalence was estimated using the National Health and Nutrition Examination Survey, 2013 to 2018. Incidence was estimated using ordinary differential equations assuming static incidence at steady state and fit using Bayesian techniques. Model inputs included estimates of proportion of asymptomatic cases, natural clearance, and time to symptomatic treatment seeking. Posterior distributions were drawn, and uncertainty was reported, from 25th (Q1) to 75th (Q3) percentiles. Aggregated measures were estimated by combining component distributions.Results: Among 15-to 59-year-olds in 2018, the number of prevalent TV infections was 2.6 (Q1, 2.4; Q3, 2.7) million overall, 470,000 (Q1, 414,000; Q3, 530,000) among men, and 2.1 (Q1, 2.0; Q3, 2.2) million among women; the numbers of incident infections were 6.9 (Q1, 6.2; Q3, 7.6) million, 3.3 (Q1, 2.8; Q3, 3.8) million, and 3.5 (Q1, 3.1; Q3, 4.0) million among all persons, men, and women, respectively. Persons aged 15 to 24 years comprised 15.6% and 16.3% of all prevalent and incident infections, respectively; prevalence and incidence in both sexes increased with age. Incidences in both sexes were highly dependent on estimates of natural clearance, which were based on few data.Conclusions: Prevalence and incidence of TV are substantial in the United States, particularly among those 25 years or older. Although estimated prevalence is higher in women, estimated incidence is similar in men and women. Data on key parameters of TV infection are limited; future research should focus on clarifying the natural history of TV.

Sexually Transmitted Infections Among US Women and Men: Prevalence and Incidence Estimates, 2018

“…Second, uncertainty intervals presented here may differ from those presented in the corresponding STI-specific articles; this arises from our showing the 25th, 50th, and 75th percentiles of the distributions used to generate total prevalence and incidence estimates. [9][10][11][12][13][14][15] Lastly, sex is a key-stratifying variable in these analyses; however, in many of the data sources used, it is not clear whether these data represent sex at birth or gender identity. As such, there could be misclassification of prevalent or incident cases based on sex at birth or gender identity.…”

“…Table 1 provides a summary of the data sources used for each STI, and more detailed information on the methodology for estimating the prevalence and incidence of each STI is found in the articles that follow in this Special Issue. [9][10][11][12][13][14][15] We then calculated the number of prevalent and incident infections by multiplying each STI's updated per-capita estimates by the 2018 full resident population estimates from the American Community Survey. 16 To estimate the total number of incident and prevalent STIs, aggregated across all STIs, we first characterized each STI's empirical frequency distribution of prevalence and incidence by Chesson for providing expertise and input for the ordinary differential equation model development.…”

The Estimated Direct Lifetime Medical Costs of Sexually Transmitted Infections Acquired in the United States in 2018

“…Values for the probability that the infection is symptomatic, the probability of treatment for symptomatic infections, and the probability of treatment for asymptomatic infections were obtained for chlamydia, gonorrhea, and trichomoniasis from the respective models of these STIs described in this Special Issue. 19,20 Estimates of the medical cost of treatment of infection for chlamydia, gonorrhea, and trichomoniasis were obtained from recent analyses of medical claims data. 7,21 For chlamydia and gonorrhea, the decision trees also included the possibility of epididymitis in men and PID in women.…”

“…First, the estimates of STI incidence that we used for 2018 were based on modeling approaches that are more robust, comprehensive, and transparent than in the previous study, as described in more detail in the source studies. 19,20,[43][44][45][46] Second, for all STIs examined, with the exception of HBV, we obtained lifetime cost estimates from studies published in this Special Issue. [10][11][12][13]15 Because full articles were devoted to estimating the lifetime cost of a single STI or a group of related STIs, the methods, assumptions, and data sources have been described and documented in far more detail than previously.…”

“…Limitations associated with the models that provided the incidence estimates we used include a scarcity of data to inform the model parameters. 19,20,[43][44][45][46] Similarly, estimates we applied of the lifetime medical cost per infection are limited by uncertainties regarding the cost of treatment, the probability of treatment or uptake of therapy, the probability and cost of sequelae, and other factors, as described in more details in the source articles. [10][11][12][13]15 We addressed these unavoidable limitations by calculating ranges for the estimated lifetime cost of STIs acquired in 2018, using an approach specifically designed to reflect the likely impact and magnitude of the effect of the uncertainty in the studies that informed our analysis.…”