Trichomonas vaginalis parasite, high-speed light microscopy. T. vaginalis is a protozoan that inhabits the human urogenital tract, causing the sexually transmitted infection trichomoniasis. The disease is typically symptomless in men, many of whom carry it without knowing. In women it can cause inflammation of the urethra, vagina and cervix, and a foul-smelling discharge. Each individual protozoan is pear-shaped, and measures some 9x7 micrometres. At this speed, the beating of its flagella is evident, four of which extend away from the cell while the fifth wraps around it. At the other end of the cell is a spike called the axostyle. Treatment is with a drug such as metronidazole. Filmed with differential interference contrast illumination, at 200 frames per second.