Life cycle of Trichomonas vaginalis, the cause of trichomoniasis in humans
Trichomonas vaginalis resides in the female lower genital tract and the male urethra and prostate (1), where it replicates by binary fission (2). The parasite does not appear to have a cyst form, and does not survive well in the external environment. Trichomonas vaginalis is transmitted among humans, its only known host, primarily by sexual intercourse (3).
From Centers for Disease Control Parasites and Health website