Life cycle of Enteromonas hominis
Both cysts (dormant stage) and trophozoites (active stage) of Enteromonas hominis are shed in feces. Infection occurs after the ingestion of cysts in fecal-contaminated food or water, or on fomites (inanimate objects or substances capable of transferring pathogens). In the large (and possibly small) intestine, excystation releases trophozoites. Enteromonas hominis resides in the large intestine, where it is regarded as a commensal (benefiting from its host but doing no harm) and is not known to cause disease.