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For further information, see CMDT Part 35-12: Trichomoniasis

Key Features

  • Copious vaginal discharge in women

  • Nongonococcal urethritis in men

  • Motile trichomonads on wet mounts

Clinical Findings

  • Caused by the protozoan Trichomonas vaginalis

  • Often asymptomatic

  • For women with symptomatic disease

    • Vaginal discharge develops after an incubation period of 5 days to 4 weeks

      • May be copious

      • Usually not foul smelling

      • Often frothy and yellow or green in color

    • Vulvovaginal discomfort, pruritus, dysuria, dyspareunia, or abdominal pain may be present

    • Inflammation of the vaginal walls and cervix with punctate hemorrhages are common

  • Most men infected with T vaginalis are asymptomatic, but it can be isolated from about 10% of men with nongonococcal urethritis

  • In men with trichomonal urethritis, the urethral discharge is generally more scanty than with other causes of urethritis


  • Traditionally made by identifying the organism in vaginal or urethral secretions

  • Examination of wet mounts will show motile organisms

  • Tests for bacterial vaginosis are often positive

    • pH > 4.5

    • Fishy odor after addition of potassium hydroxide

    • Diagnostic tests include point-of-care antigen tests, nucleic acid probe hybridization tests, and nucleic acid amplification assays, both of which offer improved sensitivity compared to wet mount microscopy and excellent specificity


  • The treatment of choice is tinidazole or metronidazole, each as a 2-g single oral dose

  • Tinidazole may be better tolerated and active against some resistant parasites

  • If the large single dose cannot be tolerated, an alternative metronidazole dosage is 500 mg orally twice daily for 1 week

  • All infected persons should be treated, even if asymptomatic, to prevent subsequent symptomatic disease and limit spread

  • Treatment failure suggests reinfection

  • However, metronidazole-resistant organisms have been reported and may be treated with

    • Tinidazole

    • Longer courses of metronidazole

    • Intravaginal paromomycin

    • Other experimental therapies

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