Trichomoniasis
BASICS
- Definition: Sexually transmitted infection (STI) caused by Trichomonas vaginalis, a motile, pear-shaped, flagellated protozoan parasite
- Clinical presentations:
- Women: Vaginitis, dysuria, yellow-green discharge
- Men: Nongonococcal urethritis, often asymptomatic
- Pregnancy risks: Preterm labor, PPROM, SGA infants, possibly stillbirth
- Also known as: Trich, Trichomonal urethritis
EPIDEMIOLOGY
| Parameter | Data |
|---|---|
| Global Incidence (2008) | >275 million new cases |
| U.S. Annual Incidence | ~1.1 million |
| Female Prevalence (US) | 2.1% (aged 14–59) |
| Male Prevalence (US) | 0.5% |
| Disparities | 9.6% Black women vs 0.8% others; 3.4% Black men |
| Pediatric | Rare; suggests abuse if diagnosed in prepubertal |
| Neonatal | May present as lung or vaginal colonization |
ETIOLOGY & PATHOGENESIS
- Organism: Trichomonas vaginalis
- Environment: Anaerobic; optimal pH 5.5–6.0; survives several hours in moist surfaces
- Transmission: Primarily sexual, but nonsexual transmission is possible
- Divides by: Binary fission
RISK FACTORS
- Multiple partners, unprotected sex
- History of other STIs
- Partner with untreated infection
- Douching or feminine hygiene products
- Note: Hormonal contraceptive use not a risk factor
ASSOCIATED CONDITIONS
- Other STIs including HIV
- Bacterial vaginosis
CLINICAL FEATURES
Women (up to 85% asymptomatic)
- Yellow-green, frothy, malodorous vaginal discharge
- Vulvar itching, dysuria
- Symptoms worsen during menstruation
Men (77% asymptomatic)
- Dysuria, pruritus after intercourse
- Urethral discharge (scant)
PHYSICAL EXAM
| Women | Men |
|---|---|
| Vaginal erythema | Penile discharge |
| Frothy, green discharge | Possibly asymptomatic |
| "Strawberry cervix" <5% |
DIFFERENTIAL DIAGNOSIS
| Women | Men |
|---|---|
| Bacterial vaginosis | Chlamydia |
| Candidiasis | Gonorrhea |
| Chlamydia, Gonorrhea |
DIAGNOSTIC WORKUP
Initial Tests
| Test | Notes |
|---|---|
| Wet mount | Fast, cheap, low sensitivity (~26%) |
| Culture | Sensitivity >95% |