Entamoeba histolytica Life Cycle

Introduction

Entamoeba histolytica are pathogenic amoeba that are widely known for causing intestinal and extraintestinal infections in human beings. Entamoeba histolytica falls under the phylum Protozoa, the class Sarcodina and the order Lobosa. Entamoeba histolytica causes dysentery by invading the mucosa and submucosa layers of the large intestine in human beings. E. histolytica are commonly found in tropical and subtropical countries. The life cycle of E. histolytica begins and ends inside one single host, i.e., an individual human being.

Let’s look at the Entamoeba histolytica to get a better understanding.

Life Cycle of Entamoeba histolytica:

1) Cyst – Stage 1 –

Infection occurs by ingestion of mature cysts through fecally contaminated water or food. Due to protection from walls, cysts survive several days and sometimes weeks. They are responsible for transmission.

2) Excystation – Stage 2 –

Excystation is the process by which cysts transform into trophozoites. When the cysts enter the ileum of the small intestine of the host, the process of excystation begins. Trophozoites are released in the small intestine and from here they migrate to the large intestine.

3) Trophozoite – Stage 3 –

Trophozoites are unicellular parasites that measure from 14 to 18 mm in diameter. They multiply in the small intestine by binary fission to produce cysts that exit via human stool. Several trophozoites remain inside the lumen of the small intestine. The rest attach themselves to the intestinal mucosa, enter the bloodstream and further grow in the extraintestinal regions of the host like lungs, liver, brain.

Conclusion:

Entamoeba histolytica invasion in human hosts vary from showing zero symptoms to being fatal. This parasite, discovered in 1859 by Lambl. S. Chaudin, showed the difference between pathogenic and non-pathogenic forms of amoeba.

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