Entamoeba histolytica

Entamoeba histolytica. Trophozoite in fecal smear (saline wet mount, high power). Numerous ingested erythrocytes are present in the cytoplasm, but the nucleus is not visible. The presence of red blood cells in an amebic trophozoite is virtually diagnostic of E. histolytica infection. In rare and poorly documented instances, trophozoites of Entamoeba coli have been reported to have ingested erythrocytes. Entamoeba dispar, the nonpathogenic intestinal ameba that is morphologically identical to E. histolytica, does not invade tissue nor does it ingest red blood cells.