Trichomoniasis: Transmission and Treatment
Metronidazole 2g orally in a single dose is the CDC-recommended first-line treatment for trichomoniasis, with cure rates of 90-95%, while trichomoniasis is contracted through sexual contact and requires treatment of all sexual partners to prevent reinfection. 1
Transmission of Trichomoniasis
Trichomoniasis is a sexually transmitted infection caused by the protozoan parasite Trichomonas vaginalis. It is transmitted through:
- Sexual contact with an infected partner
- Direct genital-to-genital contact during sexual activity
- Sharing of contaminated sex toys (less common)
The infection is site-specific for the genitourinary tract and has been isolated from virtually all genitourinary structures 2. Both symptomatic and asymptomatic infections can be transmitted between partners.
Diagnosis
Trichomoniasis can be diagnosed through several methods:
- Microscopic examination (wet mount): 60-70% sensitivity
- Culture in specialized media: More sensitive than wet mount
- Nucleic acid amplification tests (NAATs): Highest sensitivity and preferred method when available 1
Treatment Options
First-Line Treatment
- Metronidazole 2g orally in a single dose is the CDC-recommended first-line treatment for trichomoniasis, with cure rates of 90-95% 1
Alternative Regimens
- Metronidazole 500mg orally twice daily for 7 days (alternative regimen) 1
- Tinidazole 2g orally in a single dose (for patients with metronidazole allergy) 1, 3
Treatment Efficacy
Recent research suggests that the 7-day metronidazole regimen may be more effective than the single-dose treatment. A randomized controlled trial found that patients in the 7-day-dose group were less likely to test positive at follow-up than those in the single-dose group (11% vs 19%) 4.
Important Treatment Considerations
- Topical metronidazole preparations (gels, creams) are not effective for trichomoniasis, with less than 50% efficacy 1, 5
- Clotrimazole vaginal tablets and other non-nitroimidazole treatments have shown poor efficacy against T. vaginalis 6
- Patients should abstain from sexual activity until both patient and partner(s) complete treatment and are asymptomatic 1
Partner Treatment
- All sexual partners must be treated simultaneously to prevent reinfection 1, 3, 7
- Partners should be treated regardless of symptoms, as asymptomatic infections are common 2
- All recent sex partners (within 60 days) should be evaluated, tested, and treated 1
Follow-up and Treatment Failure
- Improvement in symptoms should be seen within 72 hours of starting treatment 1
- If no improvement is observed, consider an alternative regimen and reassess the diagnosis
- For treatment failure with the single dose, re-treatment with metronidazole 500mg twice daily for 7 days is recommended 1
- For repeated failures, metronidazole 2g once daily for 3-5 days can be used 1
- Consider retesting all patients 3 months after treatment due to high rates of reinfection 1
Common Pitfalls and Caveats
- Failing to treat sexual partners is the most common cause of recurrent infection
- Alcohol consumption should be avoided during treatment and for 24-72 hours after taking metronidazole or tinidazole to prevent disulfiram-like reactions
- Topical treatments alone are ineffective and should not be used as monotherapy
- Asymptomatic infections are common in both men and women, emphasizing the importance of partner treatment even when asymptomatic
In conclusion, while both single-dose and 7-day metronidazole regimens are effective, the CDC still recommends the single-dose approach as first-line therapy due to its convenience and good compliance, though the 7-day course may be more effective based on recent evidence 1, 4.