Endolimax nana

Endolimax nana is an ameba considered nonpathogenic.

Disease // Pathogenesis

Endolimax nana is a nonpathogenic ameba.

Location in the Host

Endolimax nana is found in the lumen the colon and cecum.

Geographic Distribution

Endolimax nana is found worldwide.

Life Cycle

Image courtesy of CDC

Morphology & Diagnosis

Endolimax nana is detected in ova & parasite examinations. Endolimax nana is a small ameba. Trophozoites are 6-12u while the cyst are 5-10u.

The trophozoite will have a single nucleus with a karyosome that takes up a good portion of the nucleus and is irregularly shaped. Peripheral chromatin is absent on the nuclear membrane. The cytoplasm may contain ingested bacteria.

The cyst contain four nuclei when mature. Immature cysts are rarely seen. They are spherical in shape. The karysome in the nuclei is not as large as seen in the trophozoite stage but nevertheless it still is prominently larger then that seen in the other Entamoeba species.


Endolimax nana in formalin concentrate – photo by W. Vientos
Endolimax nana in trichrome stain – Photo courtesy of CDC