Amoebae are basically unicelluar microorgansims which has life cycle that is simple. Its life cycle is divided into two stages: the actively motile feeding stage (trophozoite) and the motionless, resistent, infective stage (cyst). Replication is accomplised by binary fission (splitting of trophozoite) or by the development of numerous trophozoites within the mature multinucleated cyst.

Most amoebae found in humans are commensal organisms.


Entamoeba Histolytica


Psysiology and Structure:

The trophozoite of Entamoeba Histolytica is the most pathogenic of the intestinal amebae that is found in humans. It measures 10-60 micrometers. Trophozoite cytoplasm is finely granular and may contain inclusions. It is usually absent in ingested bacteria and yeast.

The cyst of Entamoeba Histolytica measures 10-20 micrometers. A mature cyst contains 4 nuclei while an immature cyst contains less than 4 nuclei. The presence of evenly distrubuted peripheral nuclear xhromatin is crucial in the indentification of Entamoeba Histolytica.


Life cycle of Entamoeba Histolytica:

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Clinical Syndromes:

The outcome of infection may result in a carrier state. Amebasis is usually acquired by ingestion of contaminated water or food containing amebic cysts, although transmission as a sexually transmitted disease by male homosexuals has occured.

Asymptomatic carriers may also transmit disease.

Symptimatic patients may have abdominal pain and diarrhea (in worse situations, bloody diarrhea ensue), ulcers forming in the appendix, cecum and other parts of the colon. Ulcers are flask-shaped taht appears to be raised with a small mucosal opening and an eroded area beneath the surface.


Treatment, Preventation and Control:

  • Patient can be treated with Iodoquinol (
  • Human infection may result from the ingestion of food and water contaminated with human feces or as a result of specific sexual practices.  Therefore, adequate sanitation measures such as chlorination and filtration of water supplies may limit the spread of these and other enteric protozal infections.