Trichomonas vaginalis is a single celled protozoan parasite that causes trichomoniasis. It is found in the vagina and urethra (mostly in men). Women can aquire trichomoniasis from infected men or women. Men mostly acquire trichomoniasis from infected women. Trichomoniasis is easily curable.

The following sources provide excellent information about this infection:

Centers for Disease Control

American Sexual Health Association

Planned Parenthood

pubMed

Medline plus

Women's Health.gov

Mens stuff