Trichomoniasis

Trichomonas vaginalis is a type of parasite spread through sexual intercourse

Aetiology

Causative organism:
  • Trichomonas vaginalis
Morphology (important for venereology exams):
  • Protozoan parasite
  • Pear-shaped trophozoite
  • 4 anterior flagella
  • Undulating membrane
  • Size: 7–23 µm
  • Exists only as trophozoite (no cyst stage)
Biological characteristics:
  • Motile (jerky/twitching movement)
  • Anaerobic metabolism
  • Cannot survive long outside the human body

Clinical presentation

Symptoms

  • Up to 50% of cases of trichomoniasis are asymptomatic
  • When symptoms occur, they are non-specific:
    • Vaginal discharge - typical description of the vaginal discharge is frothy and yellow-green, may have a fishy smell
    • Itching
    • Dysuria (painful urination)
    • Dyspareunia (painful sex)
    • Balanitis (inflammation to the glans penis)

Signs

  • Examination of the cervix can reveal a characteristic ‘strawberry cervix’

Investigations

Microscopy (Traditional Method)

  • NaCl wet mount/Giemsa stain microscopy
  • Motile, flagellated trophozoites
  • Sensitivity: ~50–60% (low)

Culture

  • Diamond’s medium
  • More sensitive than wet mount
  • Slower results

Nucleic Acid Amplification Tests (NAATs) – Gold Standard

  • Highest sensitivity and specificity
  • Can be used on vaginal swabs or urine

Point-of-Care Tests

  • Rapid antigen tests
  • Useful in low-resource settings

Management

  • Metronidazole