Question
Trichomanas vaginalis
Answer
Trichomonas vaginalis: a flagellated, pear-shaped protozoan parasite, causing trichomoniasis, one of the most common sexually transmitted infections worldwide.
Morphology: exists only in the trophozoite form (no cyst stage); pear/oval shaped, approximately 10–20 μm, with four anterior flagella, an undulating membrane running along part of its length, and a prominent axostyle projecting from the posterior end.
Transmission: primarily sexual contact; can rarely also be transmitted via fomites (shared towels/wet objects) given the organism’s ability to survive briefly outside the host in moist conditions.
Clinical features: in women — frothy, malodorous, greenish-yellow vaginal discharge, vulvovaginal itching/irritation, and a characteristic “strawberry cervix” (punctate haemorrhages) on speculum examination; men are frequently asymptomatic carriers, though urethritis can occur.
Laboratory diagnosis:
- Wet mount microscopy of vaginal/urethral discharge — direct visualization of actively motile trophozoites (the classical rapid bedside test, though sensitivity is only moderate).
- Culture (e.g., Diamond’s medium) — more sensitive than wet mount, considered a traditional gold standard.
- NAAT (nucleic acid amplification tests, e.g., PCR) — the most sensitive and specific modern diagnostic method.
- Rapid antigen tests — point-of-care immunochromatographic assays available in some settings.
Treatment: Metronidazole (or Tinidazole), with treatment of sexual partners recommended to prevent reinfection.