Entamoeba histolytica infection is a parasitic intestinal infection induced by the amoeba entamoeba histolytica, also known as E. histolytica. This protozoan passes the body when cysts are consumed in water or food. It can also enter the body via direct contact with feces.

The cysts are a latent type of parasite that can sustain in the soil or surroundings for a few months after being stored in feces. The microscopic cysts can be found in fertilizer, soil or water polluted with contaminated feces.

Cysts can be transmitted by food handlers while making preparations or handling food. It is also possible to transmit the virus during anal or oral sex and colonic irrigation. Cysts enter the body and become lodged in the digestive tract. They then emit a trophozoite, an intrusive, active form of the parasite.


Entamoeba histolytica infection can aggravate colitis, bloody diarrhea and tissue damage in people who have no signs. The person can then transmit the disease by excreting infected feces that contain new cysts.

When signs do appear, they usually appear one to four weeks after the cysts have been consumed. At this stage, signs such as loose stools and abdomen cramping are common.

Trophozoites may attack the intestinal walls, penetrate the bloodstream, and move to different internal organs in a rare complication of the condition. They typically invade the liver, but they can also invade the brain, lungs, heart, or other organs.

If trophozoites infiltrate an internal organ, they may cause the following:


After discussing your latest medical and travel history, your healthcare provider may suspect Entamoeba histolytica infection. Because E. histolytica resembles other parasites, including E. dispar, diagnosing Entamoeba histolytica infection can be difficult.

Your doctor may order the following tests to identify E. histolytica and rule out other potential issues:

  • Stool samples
  • Antigen testing


Whether or not you have symptoms, Entamoeba histolytica infection must be addressed if tests reveal the existence of E. histolytica. Treatment is typically not justified if tests only identify E. dispar, another amoeba that may induce Entamoeba infection, because it is nonpathogenic.

In general, the treatment comprises the following:

  • Antiamoebic drug
  • Antibiotics
  • Surgery

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