Infectious Disease Compendium

Trichomonas vaginalis


A protozoa.

Epidemiologic Risks

Incubation is 5 to 28 days. Diagnose on wet mount.

Spread sexually, one the few STD's that may be spread non sexually, (:still, if you got it from a toilet seat, that has to be an uncomfortable place to have sex.:).

Can be found in semen (the Navy has so many ID issues) (PubMed).

Prevalence is 0.5% and 1.8% among males and females. Infection prevalence is 4.2% among black males, 8.9% among black females, and 0.03% and 0.8%, among males and females of other races/ethnicities (PubMed).


Up to half can be asymptomatic, it usually causes vaginitis: discharge and irritation; men, when symptomatic, get urethritis. 70% of male partners will have the infection, 77% of whom will be asymptomatic (PubMed). Increases the spread of HIV (PubMed).


A single dose 2 gm of metronidazole or 500 mg po bid x 7 d.


Resistance to metronidazole increasing is increasing (PubMed), treatment is problematic. Topical treatment will fail. Treat the partner to prevent relapse. What to do with a trich knee is uncertain.

Last Update: 07/15/18.