CLINICAL ACTIONS: 

Diagnostic testing for T. vaginalis should be performed in women seeking care for vaginal discharge (yellow-green, with or without irritation). Screening might be considered for women receiving care in high-prevalence settings.

To diagnose Trichomoniasis

• Perform nucleic acid amplification testing (NAAT), which detects T. vaginalis genetic material, is highly sensitive and which is three to five times more likely to identify T. vaginalis infections than wet-mount microscopy, a method with poor sensitivity
• Culture was considered the gold standard before molecular testing and is less sensitive than newer tests
• If wet preparations are used, despite lower sensitivities, slides should be evaluated immediately as sensitivity declines with time
  • If negative, consider follow up with a NAAT to make sure infection is truly not present
• T. vaginalis may be an incidental finding on a Pap test, neither conventional nor liquid-based Pap tests are considered diagnostic tests for Trichomoniasis, because false negatives and false positives can occur

SYNOPSIS:

Trichomoniasis is the most prevalent nonviral sexually transmitted infection in the United States.  T. vaginalis infection affects >11% of women aged ≥40 years and infection rates reflect health disparities: 13% of black women are affected compared with 1.8% of non-Hispanic white women. While some infected women will present with vaginitis, the majority of those infected (70%-80%) will have minimal or no symptoms. Screening asymptomatic women may be done in high risk settings (such as an STD clinic), however, data are lacking on whether screening and treatment for asymptomatic trichomoniasis is beneficial. Decisions about screening might be informed by local epidemiology of T. vaginalis infection rates.

KEY POINTS:

The nitroimidazoles are the only class of antimicrobial medications known to be effective against T. vaginalis infections. Of these drugs, metronidazole and tinidazole have been cleared by FDA for the oral or parenteral treatment of trichomoniasis.

The CDC recommends the following

• Recommended Regimen
  • Metronidazole 2 g orally in a single dose or
  • Tinidazole 2 g orally in a single dose

• Alternative Regimen 
  • Metronidazole 500 mg orally twice a day for 7 days

• Alcohol consumption should be avoided during treatment with nitroimidazoles
  • To reduce the possibility of a disulfiram-like reaction, abstinence from alcohol use should continue for 24 hours after completion of metronidazole or 72 hours after completion of tinidazole
• Providers should advise persons infected with T. vaginalis to abstain from sex until they and their sex partners are treated (i.e., when therapy has been completed and any symptoms have resolved)
  • Testing for other STDs including HIV should be performed in persons infected with T. vaginalis
• Retest for T. vaginalis is recommended for all sexually active women within 3 months following initial treatment
  • Testing by NAAT can be conducted as soon as 2 weeks after treatment
• Treat current partners to avoid reinfection and further transmission
  • Partners should be advised to abstain from intercourse until they and their sex partners have been adequately treated and any symptoms have resolved
  • In States where legally allowed (see learn more below), consider Expedited Partner Therapy (EPT) which allows the patient herself to provide medications to her partner when there are limited public health services to treat a partner, or concern that the partner will not have access to treatment

PREGNANCY: 

• T. vaginalis infection is associated with two to threefold increased risk for HIV acquisition, preterm birth, and other adverse pregnancy outcomes among pregnant women
  • However, some trials have not shown improvement in perinatal morbidity with treatment
• Symptomatic pregnant women, regardless of pregnancy stage, should be tested and considered for treatment
  • Recommended regimen: Metronidazole 2 g orally in a single dose
• The benefit of routine screening for T. vaginalis in asymptomatic pregnant women has not been established

HIV:

• Among women with HIV infection, up to 53% are also infected with T. vaginalis which has been associated with an increased risk for PID
• Routine screening of asymptomatic women with HIV infection for T. vaginalis is recommended on entry to care, and then annually
  • Pregnant women, including those who are asymptomatic, should be screened and treated as necessary because T. vaginalis infection is a risk factor for vertical HIV transmission
• The recommended regimen in the setting of HIV is as follows
  • Metronidazole 500 mg twice daily for 7 days
• Retest in 3 months with NAAT

Learn More – Primary Sources:

CDC: Trichomoniasis Treatment Guidelines

CDC: Trichomoniasis Fact Sheet for Your Patients

CDC: Expedited Partner Therapy

Related ObG Topics:

STD Screening in Pregnancy: CDC Recommendations

Screening for Sexually Transmitted Diseases – Who, When and How Often?

Pelvic Inflammatory Disease – CDC Treatment Guidelines

The ABCs of PID Diagnosis – What You Need to Know