Also known as Trichomonas vaginalis or “Trich”, this is one of the most common sexually-transmitted diseases. It is caused by a parasite that thrives in the vaginal environment, usually transmitted by sexual contact but also in warm moist environments such as hot tubs. Trichomonas may affect not only the vagina but also the urinary tract of both women and men. Signs include: Vaginal irritation; a fishy odor; a greenish/yellow vaginal discharge; pain with intercourse and/or with urination. Some women may have no symptoms at all.