Trichomoniasis

Introduction

Trichomoniasis is caused by the flagellated protozoan called Trichomonas vaginalis.

It is an extremely common infection, almost always transmitted via sexual contact.

Women are far more frequently affected and more likely to have symptoms.

Men are more likely to be asymptomatic
and serve as carriers

Clinical features

• Vaginal discharge: a white-yellow frothy discharge is characteristic
  • Burning sensation
  • Dysuria
  • Dyspareunia
  • The liabia are often swollen
• The cervix may have punctuated
  haemorrhages producing a strawberry-like surface when viewed with a colposcope
• Some men may have dysuria or a minimal urethral discharge and balanoposthitis
• Co-infection with N. gonorrhoeae is common

Differential diagnoses

• Other causes of vaginal discharge or urethral discharge: see Gonorrhoea

Complications

• Acute salpingitis
• Adverse pregnancy outcomes, particularly premature rupture of membranes, pre-term delivery and low birth weight

Investigations

• Microscopy and culture of vaginal discharge

Treatment objectives

• Eliminate the organism in the patient and sexual partner(s)
• Prevent re-infection
• Prevent complications
• Counsel and screen for possible co-infection with HIV so that appropriate management
  can be instituted

Drug treatment

Recommended regimen:

• Metronidazole 2g orally in a single dose

Or:

• Tinidazole 2 g orally in a single dose

Alternative regimen:

• Metronidazole 400 mg or 500 mg orally every 12 hours for 7 days

Or:

• Tinidazole 500 mg orally every 12 hours for 5 days

Note: Other 5-nitroimidazoles are also effective, both in single and in multiple dose regimens.

• Asymptomatic women with trichomoniasis should be treated with the same regimen as symptomatic women
• Recommended regimens for male urethral infections: same as for women
• Patients not cured with the repeated course of metronidazole may be treated with a regimen consisting of metronidazole 2 g orally daily, together with 500 mg applied intravaginally  each night for 3-7 days
• Vaginal preparations of metronidazole are available in many parts of the world, but are only recommended for the treatment of refractory infections, not for the primary therapy of trichomoniasis.

Recommended regimen for neonatal infections

• Metronidazole 5 mg/kg orally, every 8 hours for 5 days

Infants with asymptomatic trichomoniasis, or urogenital colonization persisting past the fourth month of life should be treated with metronidazole

Notable adverse drug reactions, caution and contraindications

Metronidazole

• It causes a disulfiram-like reaction with alcohol
• Avoid high doses in pregnancy and breast feeding
• It may cause nausea, vomiting, unpleasant taste, furred tongue, and gastro-intestinal disturbances
• It is generally not recommended for use in the first trimester of pregnancy

Prevention

• Counselling, Compliance, Condom use
• Contact treatment