Causal Agent:
Chilomastix mesnili, a nonpathogenic flagellate.

Life Cycle:

The cyst stage is resistant to environmental pressures and is responsible for transmission of Chilomastix.  Both cysts and trophozoites can be found in the feces (diagnostic stages) .  Infection occurs by the ingestion of cysts in contaminated water, food, or by the fecal-oral route (hands or fomites) .  In the large (and possibly small) intestine, excystation releases trophozoites.  Chilomastix resides in the cecum and/or colon; it is generally considered a commensal whose contribution to pathogenesis is uncertain.  Animals may serve as a reservoir for Chilomastix.

Geographic Distribution:
Worldwide.