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Entamoeba hartmanni Infection

Entamoeba hartmanni (Nonpathogen)

This organism belongs to the amebae, is a nonpathogen, and causes no disease.  Both the trophozoite (usual size, 4-12 µm) and cyst forms (usual size, 5-10 µm) can be found in clinical specimens.


Trophozoite <12 microns       Cyst <10 microns

Life Cycle:
Large bowel, organisms passed in feces

Fecal-oral transmission via cyst form; contaminated food and water

Worldwide, primarily human-to-human transmission

Clinical Features:

Clinical Specimen:
Intestinal:  Stool

Laboratory Diagnosis:
Intestinal:  Ova and Parasite examination (concentration, permanent stained smear); E. hartmanni will be identified based on size differences (differentiate from the Entamoeba histolytica/E. dispar group).

Organism Description:
Trophozoite:  Evenly arranged nuclear chromatin, central karyosome, fine cytoplasm (will normally not contain ingested RBCs)
Cyst:  Usually contains chromatoidal bars with smooth, rounded edges, mature cyst contains 4 nuclei (often two-nucleated cysts seen).

Laboratory Report:
Entamoeba hartmanni (indicate trophozoites and/or cysts).


Improved hygiene, adequate disposal of fecal waste, adequate washing of contaminated fruits and vegetables

E. hartmanni will be differentiated from other organisms in the Entamoeba genus by size differences.