Trichomonas Vaginalis

What’s New

Recommended treatment is 7 day course of metronidazole. Stat dose has a higher rate of
treatment failure.

Introduction

Trichomonas vaginalis (TV) is a flagellated protozoan that is a parasite of the genital tract.

Due to site specificity, infection almost always follows direct inoculation of the organism (intravaginal or intraurethral) and is thus almost exclusively sexually transmitted.

Note: there are other species of Trichomonas which are not sexually transmitted, eg, Trichomonas Faecalis, so it is therefore important to clarify this with the testing laboratory if further differentiation is required.

In adult female cases urethral infection is present in 90% of episodes, although the urinary tract is the sole site of infection in <5% cases.

In men infection is usually of the urethra.

The most obvious host response to infection is a local increase in polymorphs.

Infection is associated with an increased risk of HIV transmission.

There is a spontaneous cure rate in the order of 20/25%.

TV should be managed in local specialist sexual health services or in consultation with.

This guidance is aimed primarily at people aged 16years or older.

Symptoms & Signs in Females

Symptoms (10-50% asymptomatic)

Vaginal discharge
Itch
Dysuria
Burning
Occasionally lower abdominal discomfort or vulval ulceration

Signs (5-15% nil abnormal on examination)

Erythema – vaginitis and vulvitis
Discharge – in up to 70%. The classical frothy yellow discharge is seen in 10-30% of females.
Odour
2% “strawberry” cervix visible to the naked eye

Symptoms & Signs in Males

Symptoms (15-50% asymptomatic; Often present as contacts of infected female partners)

Urethral discharge
Dysuria
Frequency

Signs

Urethral discharge
Rarely balanoposthitis

Diagnosis in Females

It is important to check with your local laboratory if they have facilities for culture of TV and how to request this is done. Some laboratories will do microscopy alone for TV.

Females – Investigations

Vaginal pH – Use a swab/loop to collect discharge from the lateral vaginal wall and put it on narrow range pH paper (range 3.8-5.5). TV is associated with an elevated vaginal pH of > 4.5
IMMEDIATE microscopy (where available) Sensitivity 45-60%
- Wet mount preparation (normal saline) from posterior vaginal fornix
- Read within 10 minutes of collection – motility decreases with time
- Direct observation of trichomonas
Where IMMEDIATE microscopy is not available:
- The diagnosis may be made provisionally if there is profuse frothy discharge, vaginitis and a raised pH
HVS (from posterior fornix) should arrive in the lab within 6 hours
Culture of TV Specific culture media will diagnose up to 95% cases
Point of care tests are available. False positives may occur especially in populations of low prevalence – consider confirming positives in this situation
Nucleic acid amplification tests (NAATS) are available for diagnosis of TV. These offer the highest sensitivity. These should be the test of choice where resources allow
Offer full STI testing

NB: Be aware that TV diagnosed on Liquid based cytology may have a false positive rate. If TV-like organisms are reported via SCCRS, a letter is generated via the results service requesting the woman to attend to confirm infection prior to any treatment and/or partner notification.

Diagnosis in Males

In practice, treatment is usually epidemiological without identification of the organism, which is difficult - highest yield is from centrifuged first void urine deposit.

Microscopy of urethral smear in saline gives a diagnosis in 30% of infected males
- If there is an excess of polymorphs on initial microscopy, repeat urethral smear after TV treatment is complete. This will allow a separate diagnosis of Non-specific urethritis
Doing both a urethral swab culture (using specific culture media) and a culture of first void urine can increase the diagnostic rate (urine should not be refrigerated and ideally should be centrifuged within an hour)
Nucleic acid amplification tests (NAATS) are available for diagnosis of TV. These offer the highest sensitivity. These should be the test of choice where resources allow.
Offer full STI testing

Treatment

95% response
Treat partners simultaneously irrespective of test results
Note spontaneous cure rate in the order of 20-25%

Preferred treatment: Metronidazole 400-500mg twice daily for 5-7 days
Alternative treatment: Metronidazole 2g stat (stat dose has a higher risk of treatment
failure)
Advise to avoid alcohol for the duration of treatment and for 48 hours
afterwards with metronidazole

Clients should be advised to avoid sexual intercourse (including oral sex) for at least 1 week until they and their partner(s) has completed treatment and follow-up
Give detailed information about the condition. The following is a link to the BASHH Patient Information leaflet Trichomonas Vaginalis

Partner Notification

All clients diagnosed with TV should see a sexual health specialist who has achieved
sexual health advisor competencies
Current sexual partners should be treated for TV and offered testing for STIs regardless of the results of their tests
Epidemiological treatment for partners is as above
Any partner(s) within the 4 weeks prior to presentation should be treated

Follow up in Females

Telephone consultation at 2 weeks with a sexual health specialist with sexual health advising competencies to check compliance, when they last had sex, and if they have any ongoing symptoms
If still symptomatic, arrange a test of cure. Optimum timing is 4 weeks after start of treatment
Complete Partner Notification
Ensure offered/ arranged testing for HIV and Syphilis taking into account relevant window period and risk exposure

Follow-up in Males

Telephone consultation at 2 weeks with a sexual health specialist with sexual health advising competencies to check compliance, when they last had sex, and if they have any ongoing symptoms
If there was an excess of polymorphs on initial urethral microscopy repeat this at follow up to ensure a diagnosis of non-specific urethritis has not been missed
If still symptomatic, arrange a test of cure. Optimum timing is 4 weeks after start of treatment
Complete Partner Notification
Ensure offered/ arranged testing for HIV and Syphilis taking into account relevant window period and risk exposure

Recurrent / Relapsing Trichomonas Vaginalis

May be due to inadequate therapy, re-infection or resistance.

Confirm partner(s) has been treated and that they have abstained from sexual contact
Check compliance with therapy and exclude vomiting from metronidazole
Once re-infection and non-compliance has been excluded:

1. Repeat course of Metronidazole – 400-500 mg twice daily for 7 days
2. For patients failing 1. Try Metronidazole 2g daily orally for 5 to 7 days or 800mg three times daily for 7 days

If patient fails on the above 2 options discuss with a senior colleague in GUM before considering alternative options.