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Nonpathogenic enteric protozoa

Peter F Weller, MD, MACP
Karin Leder, MBBS, FRACP, PhD, MPH, DTMH
Section Editor
Edward T Ryan, MD, DTMH
Deputy Editor
Elinor L Baron, MD, DTMH


Several nonpathogenic protozoa inhabit the intestinal tract and may be identified in stool specimens sent to the clinical laboratory for ova and parasite examination [1,2]. Since these nonpathogenic parasites can be reported by the diagnostic laboratory, it is important to be able to distinguish between organisms that require treatment and organisms that do not.

The classification of nonpathogenic protozoa will be reviewed here. Several other enteric organisms, including Blastocystis hominis and Dientamoeba fragilis, are discussed separately. (See "Blastocystis species" and "Dientamoeba fragilis".)


The nonpathogenic protozoa can be divided into two groups: amebae and flagellates. The nonpathogenic amebae include:

Entamoeba gingivalis

Entamoeba hartmanni

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Literature review current through: Nov 2017. | This topic last updated: Jul 05, 2016.
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