This is a parasitic protozoan infection, the result of infection with the flagellated anaerobic trichomonas vaginalis.
  • This is the most common protozoan infection in the developed world
It is a sexually transmitted infection although men are usually asymptomatic.


  • Hard to assess due to the very high rate of asymptomatic cases. Some estimates as high as 50% of the sexually active population.


  • In men – usually asymptomatic
  • In Women –may include a fishy smelling discharge, that is usually thin, green-yellow, and frothy.
    • Strawberry cervix – in 10% of cases. The cervix has the appearance of a strawberry, due to small petechial haemorrhages.


  • To the fetus
    • Pre-term delivery
    • Low birthweight
    • Increased mortality
  • To the mother
    • Increased susceptibility to HIV


  • Triple swabs – one for chlamydia, one for gonorrhoea, and one for other infections
    • Gonorrhoea is particularly important to exclude as it often co-exists
    • Culture and microscopy – the protozoa and its flagella can be seen on microscopy and cultured in the lab for definitive diagnosis
  • Vaginal pH – >4.5


  • Metronidazole – PO 400mg/12h for 5 days, or 2g PO stat dose (one off dose)
    • Encourage treatment of the partner
    • In pregnancy, use the 5-day regimen

Related Articles