Contents
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
Complications
- Prostatitis
- Premature rupture of membranes in pregnancy
- Pre-term delivery
- Low birth weight
- Post-Parton sepsis
Differentials
Include anything that can cause vulvovaginitis:
- Candida infection
- Bacterial vaginosis
- STI
- Herpes simplex infection
- Dermatitis
- Psoriasis
- Lichen planus
- Lichen sclerosis
- Retained foreign body – e.g. tampon
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