What is Endolimax Nana?

Alexander Pearson

The Endolimax nana it is an intestinal amoeba that exclusively parasitizes the intestine of humans. However, it is a non-pathogenic commensal parasite, which means that it does not cause considerable harm to humans..

The distribution of this amoeba is cosmopolitan, but it is more likely to be found in warm and humid environments. Its prevalence is even higher in areas with poor hygiene or poor health resources.

The route of transmission is through the ingestion of food or beverages contaminated with amoeba cysts..


Although it does not cause disease like other amoebae, cases of chronic diarrhea, hives, constipation, rectal pain, vomiting, among other conditions have been reported in some patients contaminated with Endolimax nana.

Importantly, according to some surveys, the prevalence can be as high as 30% in some populations..


Endolimax nana it is the smallest of the intestinal amoebae that infect humans, hence its name "nana". This amoeba, like other intestinal amoebas, has two forms in its development: the trophozoite and the cyst.


The trophozoite has an irregular shape and its average size is quite small, 8-10μm (micrometers). It has a single nucleus sometimes visible in unstained preparations and its cytoplasm has a granular appearance..


The cyst is the infectious form of Endolimax nana, its shape is spherical and its size ranges between 5-10μm. During maturation, fully developed cysts contain 4 nuclei, although some may have as many as 8 nuclei (hypernucleated forms). The cytoplasm may contain diffuse glycogen and small inclusions.


Both the cysts and trophozoites of these microorganisms are transmitted in the stool and are used for diagnosis. Cysts are generally found in well-formed stools and trophozoites are found particularly in diarrheal stools..

1-Infected human feces contain both forms of amoeba, trophozoites and cysts.

2-Host colonization occurs after ingestion of mature cysts present in food, water or any object contaminated with fecal matter.

3-Excystation occurs in the small intestine of the infected person, which is the division of the mature cyst (with four nuclei) to give rise to 8 trophozoites that then migrate to the large intestine. Trophozoites divide by binary fission and produce cysts. Finally, both forms pass in the stool to repeat the cycle.

Due to the protection conferred by their cell walls, cysts can survive for many days, even weeks, outside they are already protected by their cell wall. Cysts are responsible for transmission.

In contrast, trophozoites do not have that protective cell wall that cysts have, which is why, once outside the body, they would be destroyed under these conditions. If a person ingests food or water contaminated with trophozoites, they would not survive the acidic environment of the stomach..


Confirmation of parasitosis is by microscopic identification of cysts or trophozoites in stool samples. However, living cysts and trophozoites are difficult to differentiate from other amoebas, such as Entamoeba histolytica, Dientamoeba fragilis Y Entamoeba hartmanni.

Cysts can be identified in concentrated wet mount preparations, stained smears, or other microbiological techniques. Typical ovoid cysts are easily identified in stool samples with iodine and hematoxylin.

The clinical importance of Endolimax nana is to differentiate it from pathogenic amoebas such as E. histolytica. Because Dwarf is commensal, specific treatment is not indicated.


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