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

Assessment and Treatment of Vaginitis

Vaginitis is the presenting symptom at millions of office visits each year in the United States. Although treatment of sporadic cases is often straightforward, recurrent cases present both diagnostic and treatment challenges. Molecular diagnostic tests are likely superior to in-office microscopy for most clinicians and most cases. In both recurrent bacterial vaginosis and recurrent vulvovaginal candidiasis, national treatment guidelines recommend an extended treatment duration with one of the first-line agents. In cases in which such treatment is not successful, vaginal boric acid is likely the cheapest and easiest alternative option. New antifungal medications offer additional but limited treatment options. Probiotics are not recommended for prevention of vulvovaginal candidiasis; however, vaginal products containing Lactobacillus crispatus may have promise for recurrent bacterial vaginosis. Trichomoniasis should be treated with a 1-week course of metronidazole; this is the only sexually transmitted infection for which treatment recommendations vary by sex. In cases in which patients do not respond to initial treatment, the diagnosis should be reconsidered, and other potential causes such as desquamative inflammatory vaginitis, genitourinary syndrome of menopause, or vulvodynia should be considered.

No Association of Trichomonas vaginalis Seropositivity with Advanced Prostate Cancer Risk in the Multiethnic Cohort: A Nested Case-Control Study

The potential involvement of a sexually transmitted agent has been suggested to contribute to the high number of prostate cancers in the United States and worldwide. We investigated the relationship of Trichomonas vaginalis seropositivity with prostate cancer risk in a nested case-control study within the Multiethnic Cohort in Hawaii and California using blood samples collected prior to cancer diagnoses. Incident cases of advanced prostate cancer (intermediate- to high-grade based on Gleason score ≥ 7 and/or disease spread outside the prostate) were matched to controls by age, ethnicity, and the date of blood collection. T. vaginalis serostatus was measured using an ELISA detecting IgG antibodies against a recombinant T. vaginalis α-actinin protein. Seropositivity to T. vaginalis was observed in 35 of 470 (7.4%) cases and 26 of 470 (5.5%) controls (unadjusted OR = 1.47, 95% CI 0.82-2.64; adjusted OR = 1.31, 95% CI 0.67-2.53). The association was similarly not significant when cases were confined to extraprostatic tumors having regional or distant spread (n = 121) regardless of grade (unadjusted OR = 1.37, 95% CI 0.63-3.01; adjusted OR = 1.20, 95% CI 0.46-3.11). The association of T. vaginalis with prostate cancer risk did not vary by aspirin use. Our findings do not support a role for T. vaginalis in the etiology of advanced prostate cancer.

Iron restriction increases the expression of a cytotoxic cysteine proteinase TvCP2 by a novel mechanism of tvcp2 mRNA alternative polyadenylation in Trichomonas vaginalis

Trichomonas vaginalis TvCP2 (TVAG_057000) is a cytotoxic cysteine proteinase (CP) expressed under iron-limited conditions. This work aimed to identify one of the mechanisms of tvcp2 gene expression regulation by iron at the posttranscriptional level. We checked tvcp2 mRNA stability under both iron-restricted (IR) and high iron (HI) conditions in the presence of actinomycin D. Greater stability of the tvcp2 mRNA under the IR than in HI conditions was observed, as expected. In silico analysis of the 3' regulatory region showed the presence of two putative polyadenylation signals in the tvcp2 transcript. By 3'-RACE assays, we demonstrated the existence of two isoforms of the tvcp2 mRNA with different 3'-UTR that resulted in more TvCP2 protein under IR than in HI conditions detected by WB assays. Additionally, we searched for homologs of the trichomonad polyadenylation machinery by an in silico analysis in the genome database, TrichDB. 16 genes that encode proteins that could be part of the trichomonad polyadenylation machinery were found. qRT-PCR assays showed that most of these genes were positively regulated by iron. Thus, our results show the presence of alternative polyadenylation as a novel iron posttranscriptional regulatory mechanism in T. vaginalis for the tvcp2 gene expression.

Direct Measurement of Nucleoside Ribohydrolase Enzyme Activities in Trichomonas vaginalis Cells Using 19F and 13C-Edited 1H NMR Spectroscopy

Trichomoniasis is the most common nonviral sexually transmitted infection, affecting an estimated 275 million people worldwide. The causative agent is the parasitic protozoan Trichomonas vaginalis. Although the disease itself is typically mild, individuals with trichomonal infections have a higher susceptibility to more serious conditions. The emergence of parasite strains resistant to current therapies necessitates the need for novel treatment strategies. Since T. vaginalis is an obligate parasite that requires nucleoside salvage pathways, essential nucleoside ribohydrolase enzymes are promising new drug targets. Fragment screening and X-ray crystallography have enabled structure-guided design of inhibitors for two of these enyzmes. Linkage of enzymatic and antiprotozoal activity would be a transformative step toward designing novel, mechanism-based therapeutic agents. While a correlation with inhibition of purified enzyme would be mechanistically suggestive, a correlation with inhibition of in-cell enzyme activity would definitively establish this linkage. To demonstrate this linkage, we have translated our NMR-based activity assays that measure the activity of purified enzymes for use in T. vaginalis cells. The 19F NMR-based activity assay for the pyrimidine-specific enzyme translated directly to in-cell assays. However, the 1H NMR-based activity assay for the purine-specific enzyme required a switch from adenosine to guanosine substrate and the use of 13C-editing to resolve the substrate 1H signals from cell and growth media background signals. The in-cell NMR assays are robust and have been demonstrated to provide inhibition data on test compounds. The results described here represent the first direct measurement of enzyme activity in protozoan parasite cells.

Clinical Evaluation of a New Molecular Test for the Detection of Organisms Causing Vaginitis and Vaginosis

In this prospective, observational, method comparison clinical study, the Xpert Xpress MVP test (MVP) was evaluated using both clinician-collected (CVS) and self-collected vaginal swabs (SVS) collected in a clinical setting. The study was conducted at 12 sites, including point-of-care (POC) settings, from geographically diverse locations in the United States. Participants were biologically female patients ≥ 14 years old with signs and/or symptoms of vaginitis/vaginosis. MVP test results for BV were compared to the BD MAX Vaginal Panel (BDVP). Results for Candida group and Candida glabrata and Candida krusei targets (species not differentiated) were assessed relative to yeast culture followed by mass spectrometry for species identification. Trichomonas vaginalis (TV) results were compared relative to a composite method that included results from the BDVP and InPouch TV culture. The investigational test demonstrated high positive percent agreement ranging from 93.6 to 99.0%, and negative percent agreement ranging from 92.1% to 99.8% for both CVS and SVS specimens, indicating it may be a valuable tool for the diagnosis of vaginitis/vaginosis in laboratory and POC settings.

Point-of-Care Diagnostic for Trichomonas vaginalis, the Most Prevalent, Non-Viral Sexually Transmitted Infection

A point-of-care (POC) diagnostic is needed for both women and men to establish universal screening and surveillance for the number one, non-viral sexually transmitted infection (STI) caused by Trichomonas vaginalis. We developed a POC diagnostic for this STI using the MedMira Rapid Vertical Flow (RVF^®) Technology test cartridge with a membrane that includes a Vertical procedural/reagent control line (referred to as CVL) and spotted with 1 µg of a 72.4-kDa truncated version of α-actinin called ACT::SOE3. This protein is a specific diagnostic target for antibody in sera of individuals with trichomoniasis. Serum antibody to ACT::SOE3 is a positive reaction with the test spot. Specificity of ACT::SOE3 was revealed with monoclonal antibodies (MAbs) generated to ACT::SOE3. Addition of negative control serum with MAb 67B reactive to ACT::SOE3 shows detection of both ACT::SOE3 and the CVL. Only positive sera of individuals had antibody reactive with ACT::SOE3 and detected the presence of the spot and the CVL. Negative control sera were unreactive with ACT::SOE3 and only showed the presence of the CVL. Importantly, to show proof-of-principle for POC application, ACT::SOE3 was detected with the positive patient sera spiked with whole blood. Finally, packaged cartridges stored with desiccant packs at 37 °C for one year gave identical results with the positive and negative human sera. Our results show the validity of this new POC serodiagnostic for this STI.

Structure-Guided Insight into the Specificity and Mechanism of a Parasitic Nucleoside Hydrolase

Trichomonas vaginalis is the causative parasitic protozoan of the disease trichomoniasis, the most prevalent, nonviral sexually transmitted disease in the world. T. vaginalis is a parasite that scavenges nucleosides from the host organism via catalysis by nucleoside hydrolase (NH) enzymes to yield purine and pyrimidine bases. One of the four NH enzymes identified within the genome of T. vaginalis displays unique specificity toward purine nucleosides, adenosine and guanosine, but not inosine, and atypically shares greater sequence similarity to the pyrimidine hydrolases. Bioinformatic analysis of this enzyme, adenosine/guanosine-preferring nucleoside ribohydrolase (AGNH), was incapable of identifying the residues responsible for this uncommon specificity, highlighting the need for structural information. Here, we report the X-ray crystal structures of holo, unliganded AGNH and three additional structures of the enzyme bound to fragment and small-molecule inhibitors. Taken together, these structures facilitated the identification of residue Asp231, which engages in substrate interactions in the absence of those residues that typically support the canonical purine-specific tryptophan-stacking specificity motif. An altered substrate-binding pose is mirrored by repositioning within the protein scaffold of the His80 general acid/base catalyst. The newly defined structure-determined sequence markers allowed the assignment of additional NH orthologs, which are proposed to exhibit the same specificity for adenosine and guanosine alone and further delineate specificity classes for these enzymes.

Burden of trichomoniasis among older adults in the United States: a systematic review

Despite being one of the most common sexually transmitted infections (STIs) in the United States, the epidemiology of trichomoniasis remains understudied. One population that has been historically overlooked regarding STIs is that of older adults, despite many individuals remaining sexually active well into their older years. We investigated the reported prevalence and incidence of trichomoniasis in adults aged ≥45years in the United States using a systematic literature review. Twelve articles were included in the review, all assessing prevalence of trichomoniasis in this age group. Notably, no included articles assessed trichomoniasis incidence. Data collected encompassed several decades, from 1993 to 2016. Estimates of infection prevalence varied widely and ranged from 0.2% to 21.4% in included populations, with the highest prevalence typically seen among individuals seeking diagnostic testing for STIs. Several studies found increased risk for trichomoniasis in older patients compared to younger age groups. This is the first review to examine the risk of trichomoniasis in older adults, and the surprisingly high prevalence suggests that older adults may merit increased screening for trichomoniasis and sexual health education.

Clinical Manifestation and Epidemiological Finding of Trichomonas vaginalis Infection in Unusual Areas of Body in Neonates: A Systematic Review

BACKGROUND

This study intends to increase awareness on the clinical and laboratory diagnosis as well as health care of newborns with trichomoniasis from infected mothers, to introduce this organism as a respiratory pathogen with lower prevalence in other areas, and to outline its manifestations and symptoms.

METHODS

All case report articles in English language regarding the presence of T. vaginalisin unusual areas among infants, which were available in Scopus, PubMed, Science Direct, Google scholar, and Web of Science published between 1980 and 2021 were searched and reported by two independent researchers. Titles and abstracts of all articles were reviewed for initial screening.

RESULTS

After searching the articles and evaluating their quality, 9 full text articles were selected. All reported cases were from 8 different cities (4 countries) in the world. In most cases, the parasite was in the respiratory tract, but it was also reported in the brain and urogenital tract. The most common clinical symptom was respiratory distress.

CONCLUSION

Although the possibility of trichomoniasis infection in unusual areas such as genitals is low, according to the reports collected from around the world, this parasite can also be present outside the genitals. Perhaps, reviewing trichomoniasis along with other diagnoses in these cases may lead to early diagnosis and treatment of the affected neonates.

Epidemiology, natural history, diagnosis, and treatment of Trichomonas vaginalis in men

Trichomonas vaginalis infections in men are traditionally considered to be benign and consequently have been overlooked. However, men with this common sexually transmitted infection can experience urethritis, prostatitis, reduced fertility, and amplified HIV risk. In addition, men are often asymptomatic and can unknowingly spread the infection to their female sexual partners. With advances in T. vaginalis diagnostics, more men are being diagnosed, yet the optimal method of treatment in men remains unknown. The purpose of this review is to discuss the epidemiology, natural history, diagnosis, and treatment of T. vaginalis among men.

The Estimated Lifetime Medical Cost of Chlamydia, Gonorrhea, and Trichomoniasis in the United States, 2018

BACKGROUND

The purpose of this study was to provide updated estimates of the average lifetime medical cost per infection for chlamydia, gonorrhea, and trichomoniasis.

METHODS

We adapted a published decision tree model that allowed for 7 possible outcomes of infection: (1) symptomatic infection, treated, no sequelae; (2) symptomatic infection, not treated, sequelae; (3) symptomatic infection, not treated, no sequelae; (4) asymptomatic infection, treated, sequelae; (5) asymptomatic infection, treated, no sequelae; (6) asymptomatic infection, not treated, sequelae; and (7) asymptomatic infection, not treated, no sequelae. The base case values and ranges we applied for the model inputs (i.e., the probability and cost assumptions) were based on published studies.

RESULTS

The estimated lifetime medical costs per infection for men and women, respectively, were $46 (95% credibility interval, $32-$62) and $262 ($127-$483) for chlamydia, $78 ($36-$145) and $254 ($96-$518) for gonorrhea, and $5 ($1-$14) and $36 ($17-$58) for trichomoniasis. Cost estimates for men were most sensitive to assumptions regarding the probability that the infection is symptomatic, the probability of treatment if asymptomatic, and the cost of treatment of infection. Cost estimates for chlamydia and gonorrhea in women were most sensitive to assumptions regarding the probability and cost of subsequent pelvic inflammatory disease.

CONCLUSIONS

These estimates of the lifetime medical cost per infection can inform updated estimates of the total annual cost of sexually transmitted infections in the United States, as well as analyses of the value and cost-effectiveness of sexually transmitted infection prevention interventions.

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

BACKGROUND

We estimated the lifetime medical costs attributable to sexually transmitted infections (STIs) acquired in 2018, including sexually acquired human immunodeficiency virus (HIV).

METHODS

We estimated the lifetime medical costs of infections acquired in 2018 in the United States for 8 STIs: chlamydia, gonorrhea, trichomoniasis, syphilis, genital herpes, human papillomavirus (HPV), hepatitis B, and HIV. We limited our analysis to lifetime medical costs incurred for treatment of STIs and for treatment of related sequelae; we did not include other costs, such as STI prevention. For each STI, except HPV, we calculated the lifetime medical cost by multiplying the estimated number of incident infections in 2018 by the estimated lifetime cost per infection. For HPV, we calculated the lifetime cost based on the projected lifetime incidence of health outcomes attributed to HPV infections acquired in 2018. Future costs were discounted at 3% annually.

RESULTS

Incident STIs in 2018 imposed an estimated $15.9 billion (25th-75th percentile: $14.9-16.9 billion) in discounted, lifetime direct medical costs (2019 US dollars). Most of this cost was due to sexually acquired HIV ($13.7 billion) and HPV ($0.8 billion). STIs in women accounted for about one fourth of the cost of incident STIs when including HIV, but about three fourths when excluding HIV. STIs among 15- to 24-year-olds accounted for $4.2 billion (26%) of the cost of incident STIs.

CONCLUSIONS

Incident STIs continue to impose a considerable lifetime medical cost burden in the United States. These results can inform health economic analyses to promote the use of cost-effective STI prevention interventions to reduce this burden.

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

BACKGROUND

The most recent estimates of the number of prevalent and incident sexually transmitted infections (STIs) in the United States were for 2008. We provide updated estimates for 2018 using new methods.

METHODS

We estimated the total number of prevalent and incident infections in the United States for 8 STIs: chlamydia, gonorrhea, trichomoniasis, syphilis, genital herpes, human papillomavirus, sexually transmitted hepatitis B, and sexually transmitted HIV. Updated per-capita prevalence and incidence estimates for each STI were multiplied by the 2018 full resident population estimates to calculate the number of prevalent and incident infections. STI-specific estimates were combined to generate estimates of the total number of prevalent and incident STIs overall, and by sex and age group. Primary estimates are represented by medians, and uncertainty intervals are represented by the 25th (Q1) and 75th (Q3) percentiles of the empirical frequency distributions of prevalence and incidence for each STI.

RESULTS

In 2018, there were an estimated 67.6 (Q1, 66.6; Q3, 68.7) million prevalent and 26.2 (Q1, 24.0; Q3, 28.7) million incident STIs in the United States. Chlamydia, trichomoniasis, genital herpes, and human papillomavirus comprised 97.6% of all prevalent and 93.1% of all incident STIs. Persons aged 15 to 24 years comprised 18.6% (12.6 million) of all prevalent infections; however, they comprised 45.5% (11.9 million) of all incident infections.

CONCLUSIONS

The burden of STIs in the United States is high. Almost half of incident STIs occurred in persons aged 15 to 24 years in 2018. Focusing on this population should be considered essential for national STI prevention efforts.