Entamoeba Histolytica- Amoebic Dysentery

Amoeba are simple parasites that have no fixed shape and usually infect the digestive system. One type of Amoeba that affects the human colon is called E. Histolytica.

Where is it found?

This parasite is found worldwide but is more common in the tropical areas.

Life Cycle

When infected forms of the Amoeba (cystic form) is passed in the stools of an infected person and contaminate soil or drinking water, the Amoeba can be swallowed by another person. When the amoeba reach the small intestines, they divide there and pass into the stools. The life cycle then starts again.

The disease process

  1. Histolytica only causes symptoms if the parasite invades/penetrated the intestines, which only happens in 10% of the case. Otherwise this disease can have no symptoms at all.

Penetrating Amoeba cause flask shaped ulcers in the colon and continue damaging the lining of the colon as they spread, causing infection and patchy colon lining loss.

If some of the Amoeba succeed in piercing the colon all the way through then they can reach the right side of the liver via the blood stream and cause damage and enlargement of the liver. This is called Amoebic Hepatitis and can lead to Amoebic Abscesses (pus filled infection). If the abscess is untreated then it can rupture into surrounding areas of the liver. Severe infections can even destroy surrounding skin around the anus.

Signs and Symptoms

  • Large, foul smelling, brownish black, blood streaked stools.
  • There may or may not be fever depending on the extent of the infection.
  • Diarrhea
  • Abdominal pain
  • Enlarged painful liver
  • Chills
  • Weight loss
  • Jaundice
  • Red brown pus being coughed out if infection reaches lungs.
  • 6-8 stool passing per day


  • The amoeba are found in the stools of an infected person. These Amoeba also have red blood cells found inside them.


  • Drugs for infection confined to the colon- Diloxanide furoate, Iodoquinol, Paromomycin, Tetracycline.
  • Drugs for infection that has spread to other organs- Chloroquine
  • Both – Metronidazole


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