Trichomoniasis
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Introduction

Trichomoniasis 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.
In Australia, trichomoniasis is more common in older women and women from Aboriginal and Torres Straight Islander backgrounds.
  • In urban areas it is a rare cause of vaginal or urethral (in men) discharge

Without treatments, men will often clear the infection spontaneously. This is also common in women but typically takes much longer if it is cleared at all.

Epidemiology

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

Presentation

  • 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.
    • Dyspareunia
    • Dysuria
    • Vulval itch is occasionally seen and typically mild
    • 50% of women are asymptomatic
Appearance of a strawberry cervix of speculum examination
Appearance of a strawberry cervix of speculum examination

Complications

  • Prostatitis
  • Premature rupture of membranes in pregnancy
  • Pre-term delivery
  • Low birth weight
  • Post-Parton sepsis

Differentials

Include anything that can cause vulvovaginitis:

Risks

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

Investigations

  • NAAT – nucleic acid amplification testing – a type of PCR
    • Perform a high vaginal swab or first pass urine
  • Triple swabs – one for chlamydia, one for gonorrhoea, and a general MC+S swab
    • 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

Treatment

  • Metronidazole
    • PO 2g stat (with food), OR
    • PO 400mg/12h for 5 days
    • Advise avoidance of alcohol with metronidazole due to high risk of GI side effects
    • In pregnancy, use the 5-day regimen
  • Treat male contacts presumptively
  • No sexual contact for 7 days after both patients and partner have been treated
  • Contact tracing is recommended
  • Resistance is occasionally seen – in these cases – try Tinidazole 2g PO stat
  • Test of cure is not required

References

  • Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
  • Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
  • Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy
  • Trichomoniasis - Australian STI guidelines

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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) currently works as a GP Registrar and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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