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Prevention and Control of Trichomoniasis (PSM)

1. The Disease at a Glance (Epidemiological Basis)

• Estimated 156 million new cases globally per year (2020 WHO data) - making it the most common non-viral STI worldwide, exceeding chlamydia (~130 million) and gonorrhea (~90 million).
• ~6.9 million incident cases/year in the USA alone.
• Infection rates are 7-fold higher in Black women compared to non-Hispanic White women in the USA, illustrating a strong socioeconomic and racial disparity.
• Approximately one-third of new infections occur in the WHO African Region.

• Primary: Sexual intercourse (person-to-person venereal route accounts for virtually all cases).
• Non-venereal (rare): Shared towels, clothing, toilet articles, or other fomites in moist environments (the trophozoite can survive for a few hours in moist conditions).
• Vertical (perinatal): Infected mothers can pass T. vaginalis to newborn daughters during passage through the birth canal.

• Pelvic inflammatory disease (PID)
• Preterm delivery and low birth weight
• Increased risk of HIV transmission (bidirectional)
• Epididymitis, prostatitis in men

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2. Prevention Strategies

A. Primary Prevention

i. Health Education and Behavioral Change

• Public health education about safe sexual practices, especially targeting high-risk groups (adolescents, sex workers, those with multiple partners).
• Promotion of sexual abstinence or mutual monogamy as the most effective prevention.
• Reducing number of sexual partners significantly lowers transmission risk.
• Patients diagnosed with trichomoniasis should avoid sex until treatment is completed and symptoms have fully resolved.

ii. Barrier Methods (Condoms)

• Consistent and correct use of condoms (male/external or female/internal) is the single most effective measure for sexually active individuals.
• Condoms reduce risk of both acquiring and transmitting trichomoniasis.
• Partners of circumcised men may have a somewhat reduced risk (male circumcision shows some epidemiological association).
• Diaphragms and other barrier contraceptives also offer some protection.
• Note: Douching is not recommended as it increases risk of vaginal infections including trichomoniasis.

iii. Personal Hygiene

• Avoidance of shared toilet articles (towels, underwear, washcloths) - particularly important in institutional or communal settings.
• Avoidance of shared sex toys (these can transmit trophozoites between partners).
• Adequate toilet hygiene in schools and institutions.

iv. Safe Water and Sanitation

• While primarily an STI, T. vaginalis can survive in moist environments; good personal hygiene and sanitation reduce fomite transmission.

v. Vaccination (Future/Emerging)

• No licensed human vaccine exists currently.
• Vaccine research is ongoing; a commercial vaccine against Tritrichomonas foetus (a related cattle parasite) provides proof-of-concept.
• Future vaccination against T. vaginalis would be particularly valuable for high-risk individuals.

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B. Secondary Prevention

i. Screening

• Routine screening should be considered for:
  • Women at high risk (sex workers, those evaluated for other STIs)
  • HIV-positive women - screened at least annually due to T. vaginalis-associated risk for PID and HIV transmission amplification
  • Pregnant women (given risk of preterm birth and low birth weight)
• Screening tools include wet mount, culture, and NAATs.

ii. Early Diagnosis

• Wet mount microscopy of vaginal/urethral discharge: ~50-60% sensitivity in women; ~50% in men. Motile trophozoites visible.
• Direct immunofluorescent antibody staining: 70-90% sensitivity.
• NAATs (Nucleic Acid Amplification Tests): Highly sensitive and specific; first-line diagnostics for urine, endocervical, and vaginal swabs. Recommended where available.
• Culture: Sensitive and useful where NAATs are unavailable.
• Pap smear / Giemsa stain: Occasionally identifies the organism.

iii. Treatment (Prompt and Complete)

• Both metronidazole and tinidazole have a disulfiram-like effect - alcohol must be avoided for 24 hours after metronidazole and 72 hours after tinidazole.
• In pregnancy: Metronidazole is safe (no proven teratogenicity); tinidazole is NOT recommended in pregnancy.
• For resistant infections: Higher oral doses, parenteral doses, or combination oral + intravaginal metronidazole/tinidazole; intravaginal boric acid (600 mg BD × 1 month) has also shown clinical benefit.

iv. Partner Notification and Treatment

• Simultaneous treatment of all sexual partners is mandatory to prevent reinfection (the single most important control measure after diagnosis).
• Nearly 20% of male partners are coinfected and mostly asymptomatic.
• Patients should inform past and current sexual partners; health providers should assist with partner notification when direct notification is not possible.

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C. Tertiary Prevention

• Management of complications: PID, infertility prevention, HIV counseling and management.
• Follow-up rescreening after treatment (high incidence of new STIs within 1 year of an STI diagnosis underscores the need for rescreening).

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3. Herd/Community-Level Control Measures

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4. Special Population Considerations

• Neonates: Acquired during birth canal passage; treat only if symptomatic or colonization lasts >4 weeks. In children, trichomoniasis should prompt suspicion of sexual abuse.
• Pregnant women: Screen and treat symptomatic cases; metronidazole safe; treatment reduces preterm delivery risk.
• HIV-positive women: Annual screening; 7-day metronidazole regimen preferred over single-dose due to frequent recrudescence.
• Men: Often asymptomatic; routine treatment of partners is the primary strategy since they act as hidden reservoirs.

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5. Summary Table: Key PSM Points

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• Goldman-Cecil Medicine, p. 3453 (Epidemiology, Prevention)
• Harrison's Principles of Internal Medicine 22e, p. 1852 (Life Cycle, Epidemiology, Treatment)
• Medical Microbiology 9e, p. 799 (Prevention and Control summary)
• Andrews' Diseases of the Skin, p. 492 (Clinical features, treatment)
• WHO Trichomoniasis Fact Sheet (2024); CDC STI Treatment Guidelines