Trichomonas vaginalis is an anaerobic, flagellated protozoan parasite and the causative agent of trichomoniasis. Symptoms of trichomoniasis can include itching, burning, redness, and swelling of the genitals, as well as pain during sex or urination, and a thin, grayish, or yellow-green discharge. However, not all infected individuals will show symptoms. Transmission usually occurs via direct, skin-to-skin contact with an infected individual, most often through vaginal intercourse. Usually, treatment consists of metronidazole and tinidazole.