Vaginal trichomoniasis.

Trichomoniasis is the most common curable sexually transmitted infection worldwide

Although trichomoniasis is not a reportable disease, the estimated North American prevalence is 2.8%–3.1% among women and 0.2%–0.5% among men, with higher rates in patients with multiple sexual partners.1,2 Infection with Trichomonas vaginalis increases the risk of HIV acquisition and puts a pregnant person at a 40%–50% increased risk of poor outcomes, including premature rupture of membranes and preterm birth.3

Routine screening for trichomoniasis is performed only in HIV-positive women; otherwise, test only if symptomatic

Symptoms include purulent vaginal discharge, pruritis, dysuria and dyspareunia.1 Although wet mount microscopy (sensitivity 51%–65%), antigen detection (sensitivity 82%–95%) and nucleic acid hybridization (sensitivity 63%) assays are available, nucleic acid amplification testing is the most sensitive assay for detecting T. vaginalis in women.3 Testing for men is not universally available in Canada and men are typically treated empirically.

First-line treatment for pregnant and nonpregnant patients is metronidazole

Treatment with either 2 g orally once or 500 mg orally twice daily for 7 days is 82%–88% effective, with limited evidence suggesting that the 7-day regimen is superior.4 Cure rates are highest, increasing to 95%, when a partner is also treated.4

Sexual partners must be treated at the same time as the patient upon diagnosis of trichomoniasis

Concurrent treatment of sexual partners is often overlooked by clinicians and is a common reason for reinfection.1

If T. vaginalis vaginitis persists, the possibility of metronidazole resistance should be considered

As many as 1 in 10 cases of T. vaginalis may be resistant to metronidazole. 5 Persistent positive testing of a patient or their partner should prompt consideration for referral to Infectious Diseases or a sexually transmitted infections clinic, which may send a sample for culture and susceptibility testing at the United States Centers for Disease Control and Prevention. If resistance to metronidazole is confirmed, experts may request access to alternative therapies (e.g., tinidazole) through Health Canada.