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

Diagnosis

• 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

Treatment

• 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

• A 7-day course of metronidazole (500 mg orally twice daily)

  • May be more efficacious than a single dose

  • This regimen is recommended in HIV-infected women

  • May become standard for other groups

• 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