Infection: Trichmonas; TV; Trichomoniasis; Trichmonas vaginalis infection
- A type of protozoa that cases vaginal and urethral infection.
- In NZ, unlike other STIs, Trichomonas is more common in women aged >25. It is also more commonly seen in those of Maori or Pacific ethnicity, and in areas of social deprivation.
- Up to 50% of women and the majority of men will be asymptomatic.
- Vaginal discharge is the commonest symptom, which may be malodourous and frothy. Also causes vulvovaginal itch, vulval dermatitis and post-coital bleeding.
Did you know?
Infection can persist for years in women if untreated.
Who should I test?
- Test women with vaginal discharge or other vaginal and vulval symptoms.
- Not a recommended test for men with urethritis – reserved for persistent cases.
- It can take up to 2 weeks to test positive if infection occurs relating to specific sexual event.
- Male sexual contacts should be treated empirically rather than tested.
Test of choice:
Request Trichomonas NAAT
NAAT/PCR on a low vaginal swab (self- or clinician-collected; chlamydia and gonorrhoea testing should be done also, and can be shared on same swab).
- A specific kit is usually required for NAAT testing e.g. the Aptima swabs/urine kit.
- Excellent sensitivity – a negative teston a well-collected sample makes the diagnosis very unlikely
- Excellent specificity – a positive testin an at risk person makes the diagnosis highly likely
- First void urine may also be used in women, but has lower sensitivity.
If testing in a male is required discuss with the clinical microbiologist first.
Tests to avoid/specialist tests:
- Culture on a high vaginal swab is an acceptable alternative if NAAT/PCR is not available, however it is less sensitive and slower.
- Wet prep microscopy is no longer recommended due to limited sensitivity.
- Co-infection with other STIs is common.
- Test of cure is not required if symptoms resolve.
- If symptoms persist, or there are other exposures, don’t retest within 4 weeks of treatment, as the test may remain positive due to residual dead organisms.