Entamoeba is protozoan parasites that generate pseudopods and belong to the phylum Amoebozoa, class Archamoebae, and family Entamoebidae. Entamoeba has at least seven species that can live in the human gut (E. histolytica, Entamoeba coli, Entamoeba hartmanni, Entamoeba polecki, Entamoeba dispar, Entamoeba moshkovskii, and Entamoeba bangladeshi) and one that can live in the oral cavity (Entamoeba gingivalis). Although E. polecki has been linked to diarrhoea on occasion, it’s important to remember that, except for E. histolytica and E. moshkovskii, most Entamoeba species are considered commensal organisms of the large intestine. E. histolytica, E. dispar, and E. moshkovskii are the three most common and morphologically identical amoebae, all of which have quadrinucleate cysts.

On microscopy, trophozoites with mononucleate nuclei average 10–16 m in diameter while mononucleate trophozoites average 12–60 m. Entamoeba hartmanni, a quadrinucleate cyst clade member, is much smaller than E. histolytica, with cysts measuring only 10 m in diameter and trophozoites measuring 3–12 m. Larger E. coli cysts can have up to eight nuclei and are distinguished by splinter-like chromatid bodies in their cytoplasm. Entamoeba polecki is similar in size to Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii, but it possesses a large karyosome and mononucleate cyst. In most industrialised countries, E. dispar is 10 times more common than E. histolytica, whereas, in some developing countries, the two are more evenly distributed. Geographically, E. moshkovskii is also widespread.

The life cycle of Entamoeba Histolytica

Entamoeba histolytica infection is caused by ingesting mature quadrinucleate cysts from faeces-contaminated food, water, or hands. The quadrinucleate cyst is gastric environment resistant and passes through the stomach unaffected.

• When the cyst of E.histolytica reaches the caecum or lower ileum, excystation occurs, and an amoeba with four nuclei emerges, which divides into eight trophozoites via binary fission.
• Trophozoites travel to the large intestine, where they settle in the submucosal tissue.
• Trophozoites multiply in the large intestine through binary fission (the Trophozoite phase of the life cycle is responsible for producing characteristics lesion of amoebiasis).
• A specific number of trophozoites are released into the gut lumen and converted into cystic forms.
• Because the cysts generated in this way are unable to develop in the same host, they must be transferred to another vulnerable host. The cysts travel via the faeces.

The trophozoite is responsible for disease conditions

• The trophozoites invade the intestinal epithelium and produce enzymes that cause necrosis in a specific area. At the spot, there is just minor irritation.
• A classic “flask-shaped” ulcer emerges once the lesion reaches the muscular layer, which can undermine and destroy vast portions of the intestinal epithelium.
• The trophozoites infiltrate the portal circulation after progressing into the submucosa.

Diseases

• Non-invasive infection: The trophozoites are often restricted to the intestinal lumen of asymptomatic carriers and cystic passing.
• In some patients, the trophozoites infiltrate the intestinal mucosa, causing intestinal illness.
• Extraintestinal disease: trophozoites infect extraintestinal locations such as the liver, brain, and lungs through the bloodstream, causing pathologic symptoms.

The treatment for amoebiasis

If you have no symptoms but E. histolytica is discovered in a stool (faeces) sample, you will most likely be prescribed medication to kill the parasite. Diloxanide furoate is a regularly used medication. Therapy is required because even if you have no symptoms, you might still spread the infection to others. In your faeces, the amoebae will still flow out. Also, you may develop symptoms at a later time. Treatment for symptomatic amoebiasis is then determined by the severity of your symptoms.

The clinical manifestations of infection with E. histolytica

Infection with no symptoms

Between 80 and 90 percent of people infected with E. histolytica are asymptomatic; however, 4-10 percent of asymptomatic people infected with E. histolytica develop the disease within a year.

Amoebiasis in the intestine (amoebic colitis)

Amoebic colitis can cause a variety of symptoms, from moderate diarrhoea to fulminant colitis. The onset is usually slow, and patients typically describe symptoms lasting many weeks.

The following are some of the symptoms of amoebic colitis:

• Diarrhoea is a common ailment (94-100 percent )
• Stools that are bloody (70 percent )
• Pain in the abdomen (12-80 percent )
• Loss of weight (44 percent )
• A fever of more than 38°C (10 percent )
• Amoebiasis is the intestine can also cause:
• Colitis with no symptoms
• Fulminant colitis is a type of colitis that affects roughly 0.5 percent of people.
• Amoeboma is a type of amoeboma that is found in about 1% of all cases.
• Toxic megacolon–about 0.5 percent of cases have been documented.

Conclusion

Entamoeba has at least seven species that can live in the human gut (E.histolytica, Entamoeba coli, Entamoeba hartmanni, Entamoeba polecki, Entamoeba dispar, Entamoeba moshkovskii, and Entamoeba bangladeshi) and one that can live in the oral cavity. Although E.polecki has been linked to diarrhoea on occasion, it’s important to remember that, except E.histolytica and E.moshkovskii, most Entamoeba species are considered commensal organisms of the large intestine. Entamoeba polecki is similar in size to Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii, but it possesses a large karyosome and mononucleate cyst.