Enteromonas hominis, a nonpathogenic flagellate.
Both cysts and trophozoites of Enteromonas hominis are shed in feces . Infection occurs after the ingestion of cysts in fecal-contaminated food or water, or on fomites . In the large (and possibly small) intestine, excystation releases trophozoites. Enteromonas resides in the large intestine, where it is regarded as a commensal and is not known to cause disease.
Enteromonas hominis is considered nonpathogenic. The presence of cysts and/or trophozoites in stool specimens can however be an indicator of fecal contamination of a food or water source, and thus does not rule-out other parasitic infections.
Enteromonas hominis cysts.
Figure A: Cyst of E. hominis, possessing four nuclei, in a stool specimen stained with iron-hematoxylin.
Figure B: Cyst of E. hominis, possessing four nuclei, in a stool specimen stained with iron-hematoxylin.
Enteromonas hominis is identified through the detection of cysts and/or trophozoites in stool specimens. Identification is best accomplished by direct wet mounts that reveal the characteristic, jerky movement of the organisms. They may also be identified in permanent stained smears, although their affinities for stain are inconsistent and with their small size are often overlooked.
As this species is considered nonpathogenic, there are no treatment recommendations for this organism.
DPDx is an education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.cdc.gov/parasites/.
- Page last reviewed: May 3, 2016
- Page last updated: May 3, 2016
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