Clinical manifestations of infection
Most cases of T vaginalis remain in an asymptomatic carrier state, with up to 85% of women and 77% of men reporting no clinical symptoms.1 However, approximately one-third of asymptomatic carriers will experience symptoms within 6 months of infection acquisition. This latency in appearance of clinical symptoms certainly contributes to the high transmission rate of T vaginalis.
Infected men may experience purulent urethritis, dysuria, and postcoital pruritus. Common clinical symptoms in women include abnormal vaginal discharge that may be malodorous, purulent, thin, frothy, and yellow-green, as well as symptoms of dyspareunia and vulvar irritation. Punctate hemorrhages in the cervix (colpitis macularis) and vaginal walls (macular vaginitis) give the characteristic “strawberry appearance,” but these findings are seen in only 2% of affected women.7
Complications in ObGyn patients
Although T vaginalis once was regarded as more of an annoyance than a public health issue, awareness of the infection’s ramifications has increased in recent years. Because of these complications, treatment of both symptomatic and asymptomatic patients is clearly indicated.
Complications of trichomonal infection in men include balanoposthitis, epididymitis, prostatitis, urethritis, and infertility.7 In women, complications include infections of the adnexa, endometrium, and vestibular glands, as well as cervical neoplasia and increased co-infection rates with other STIs, such as bacterial vaginosis, chlamydia infection, gonorrhea, syphilis, and herpes simplex virus type 2.1
Infection in pregnancy. Adverse outcomes in pregnant women with T vaginalis infections at mid-gestation include low birth weight, preterm premature rupture of membranes, preterm delivery, and postpartum endometritis.8 A disproportionately larger share of the low birth weight rate associated with T vaginalis infections occurs in black women compared with white and Hispanic women.8 Perinatal transmission to newborns can cause fever; respiratory difficulties; urinary tract infections; nasal discharge; and, in female infants, vaginal discharge.9,10
Co-infection concerns. The increased rate of co-infection with human immunodeficiency virus type 1 (HIV-1) and T vaginalis is a major concern.11 One study found a higher concentration of HIV-1 in semen samples from men with T vaginalis and symptomatic urethritis.12 Further, T vaginalis was found in 17.4% of women with HIV screened at a public clinic in California, with almost 38% of black women affected.13 Trichomoniasis can increase the risk of HIV-1 acquisition by 1.52-fold (95% confidence interval, 1.04- to 2.24-fold), pointing toward a potential amplifying effect of T vaginalis on HIV transmission rates.14 This association may be based at least in part on the organism’s ability to cause microulcerations in the genital and urinary tract epithelium, thus creating pathways for other microorganisms to enter the vascular system.
Making the diagnosis
The nonspecific symptoms of T vaginalis create a wide differential to consider. Vaginal discharge may be due to bacterial vaginosis, vulvovaginal candidiasis, physiologic discharge, atrophy, and nonspecific inflammation. The presence of malodorous and discolored discharge increases the likelihood of bacterial vaginosis or T vaginalis infection. Pruritus often is associated with candidiasis co-infection.
The diagnosis of trichomoniasis can be confirmed in the outpatient office with the use of saline microscopy, an inexpensive test that is based on observation of motile trichomonads in a wet mount of vaginal fluid. The sensitivity of the wet mount ranges from 44% to 68% compared with culture. Culture, traditionally using Diamond’s medium, has a sensitivity of 81% to 94% and was long the gold standard; however, culture has been replaced largely by molecular and antigen testing.
Three US Food and Drug Administration (FDA)-approved NAATs for T vaginalis currently are on the market; all can detect co-infection with gonorrhea and chlamydia from the same specimen. These tests include the Aptima T vaginalis rRNA target assay (Hologic, Bedford, Massachusetts) and the BD ProbTec T vaginalis Qx (TVQ) amplified DNA assay (BD Diagnostics, Baltimore, Maryland), both of which require up to 8 hours to yield results. The Xpert T vaginalis (TV) assay (Cepheid, Sunnyvale, California) is the first NAAT that is FDA approved for use with male urine (in addition to female urine), and it yields results in 60 to 90 minutes. Sensitivity for these NAAT assays ranges from 88% to 100%.15
Point-of-care testing is preferred for rapid diagnosis and for helping the clinician provide same-visit treatment for STIs. The Solana trichomonas assay (Quidel, San Diego, California) detects T vaginalis DNA and can yield results within 40 minutes, but it requires specialized equipment for running the samples. The AmpliVue trichomonas assay (Quidel, San Diego, California) is similar to the Solana assay but it is contained within a small handheld cartridge that does not require additional equipment. Sensitivities are 92% to 98% for Solona and 90.7% to 100% for AmpliVue. The OSOM trichomonas rapid test (Sekisui, Framingham, Massachusetts) uses antigen-detection immunochromatography to provide results in 10 to 15 minutes, with 83% to 92% sensitivity and 99% specificity for vaginal specimens.15,16
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