Trichomoniasis is a common sexually transmitted infection (STI) that affects both women and men, although symptoms are more common in women.
Trichomoniasis is caused by the single-celled parasite, Trichomonas vaginalis. The vagina is the most common infection site in women, and the urethra (urine canal) is the most common infection site in men.
The parasite is sexually transmitted through penis-to-vagina intercourse or vulva-to-vulva (the genital area outside the vagina) contact with an infected partner. Women can acquire the disease from infected men or women, but men usually contract it only from infected women.
