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J Clin Microbiol. 2013 May; 51(5): 1650.
PMCID: PMC3647919

Implications of Trichomonas vaginalis Nucleic Acid Amplification Testing on Medical Training and Practice

LETTER

We read with great interest Ginocchio and colleagues' recent study on the prevalence of Trichomonas vaginalis infection and coinfection with Chlamydia trachomatis and Neisseria gonorrhoeae (1). Based on results from nucleic acid amplification testing (NAAT) of discarded urogenital samples from 7,593 U.S. women aged 18 to 89 years (recruited in 21 states; the testing protocol included the use of the APTIMA Combo 2 assay from Gen-Probe), the overall prevalences for T. vaginalis, C. trachomatis, and N. gonorrhoeae were estimated to be 8.7%, 6.7%, and 1.7%, respectively. The study found that the highest T. vaginalis prevalence was among women aged 40 years and older and that the coinfection rates were 1.3% for C. trachomatis/T. vaginalis, 0.61% for C. trachomatis/N. gonorrhoeae, and 0.24% for N. gonorrhoeae/T. vaginalis (1). The authors concluded that, while the frequencies of coinfections were relatively low, women who are being screened for C. trachomatis/N. gonorrhoeae, regardless of symptoms, should be offered T. vaginalis testing, given the high prevalence of this infection in all age groups studied.

While the recent introduction of NAAT confers distinct advantages to microscopy (“wet mount”; sensitivity, ~50%) and to culture of vaginal specimens (gold standard; sensitivity, ~75%), the expected increase in T. vaginalis numbers likely will be attributed to detection bias as opposed to actual increases in the incident rates, given the improved sensitivity of PCR-based assays (80% to 95%) (1). Wider use of NAAT, however, would raise considerations about the cost-benefits of screening and treatment of T. vaginalis infections. Whether to screen or not to screen asymptomatic individuals, for example, could become a key clinical decision point. Results from the 2001-2004 National Health and Nutrition Examination Survey suggest that the national T. vaginalis infection prevalence among U.S. women aged 14 to 49 years was over 3%; most cases lacked information on whether or not symptoms were present (2). These results were similar to emerging local estimates. In Los Angeles County, CA, a recent community health assessment of a low-income, public health clinic population of primarily unemployed or underemployed adults (59%) (2011 Los Angeles County Health and Nutrition Examination Survey; n = 718; 73% response rate), T. vaginalis prevalence was found to be nearly 3% (unpublished local health department data). Among the T. vaginalis-positive specimens (all from patients without symptoms), 75% were African American, 19% were men, and 76% were ≥30 years.

Despite being highly prevalent and having sequelae similar to those of C. trachomatis, T. vaginalis has received considerably less attention from public health officials and the medical community than other sexually transmitted infections (STIs) (3). Indeed, the infection remains a nonreportable disease in most jurisdictions. According to a recently published analysis, the costs of treating T. vaginalis infections were relatively nontrivial, totaling nearly $6.8 million annually (in 2005 U.S. dollars) (4). The figure was likely an underestimate, as the analysis did not include health care costs attributed to medical complications, such as pelvic inflammatory disease, preterm delivery, and infertility.

These findings and others, which suggest that T. vaginalis infection can lead to increased HIV transmission rates (1, 5), lend support to the growing viewpoint that testing and treatment should be expanded to include more routine screening of any women with STI risks (1). The manner in which this should be accomplished, however, may be less clear, as considerations such as public health reporting and monitoring, costs and approaches to expanding T. vaginalis screening (e.g., universal versus targeted screening), costs of treatment, and the training needs at all levels of medical education (undergraduate, graduate, continuing medical education) will require careful planning and thoughtful discussions about the meaningful use of NAAT to screen for T. vaginalis. Answers to these and other important questions can provide context and valuable insights into the workload implications of increasing T. vaginalis screening in the primary care setting, taking into account the robust care responsibilities that already exist for many primary care specialties.

ACKNOWLEDGMENTS

No financial support was received for this work.

We report no conflicts of interest and have no financial support to disclose.

REFERENCES

1. Ginocchio CC, Chapin K, Smith JS, Aslanzadeh J, Snook J, Hill CS, Gaydos CA. 2012. Prevalence of Trichomonas vaginalis and coinfection with Chlamydia trachomatis and Neisseria gonorrhoeae in the United States as determined by the Aptima Trichomonas vaginalis nucleic acid amplification assay. J. Clin. Microbiol. 50:2601–2608. [PMC free article] [PubMed]
2. Sutton M, Sternberg M, Koumans EH, McQuillan G, Berman S, Markowitz L. 2007. The prevalence of Trichomonas vaginalis infection among reproductive-age women in the United States, 2001–2004. Clin. Infect. Dis. 45:1319–1326. [PubMed]
3. Weinstock H, Berman S, Cates W. 2004. Sexually transmitted diseases among American youth: incidence and prevalence estimates, 2000. Perspect. Sex. Reprod. Health 36:6–10. [PubMed]
4. Owusu-Edusei K, Jr, Tejani MN, Gift TL, Kent CK, Tao G. 2009. Estimates of the direct cost per case and overall burden of trichomoniasis for the employer-sponsored privately insured women population in the United States, 2001–2005. Sex Transm. Dis. 36:395–399. [PubMed]
5. Sorvillo F, Smith L, Kerndt P, Ash L. 2001. Trichomonas vaginalis, HIV, and African-Americans. Emerg. Infect. Dis. 7:927–932. [PMC free article] [PubMed]

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