It multiplies by fission and is able to invade the mucosa of the large intestine where it causes ulcerations. The invasion of the mucosa of the colon takes place by using histolytic enzymes what gave the name to the species. It comes to abscesses and destruction of the intestinal capillarities raspberry red bloody stool is the result. It may be carried to the liver, lung or brain and causes abscesses in those organs. In the intestine, the ameboid form may develop into cyst, a spherical body containing four nuclei and one or more rod shaped chromatoid bodies.
Cysts are resistant to chemical and physical agents.
Ninety per cent of infected people are not obviously ill. The cysts however are able to survive for sometime outside the body and can pass uninjured through the alimentary canal to the ileum. Here each cyst gives rise to eight small infective trophozoites. Important source of infection are cyst passers which do not have signs of any disease but produce great amount of cysts which are spread by contaminated food and polluted water. If polluted water is used to irrigate plantations of vegetable and salads and human faecis are used as fertilizer the spread of Endamoeba histolytica can take place in large group of persons.