Amoebic dysentery infection. Illustration showing human digestive system with amoeba cells in the foreground. Entamoeba histolytica is an anaerobic parasitic protozoan that causes amoebic dysentery in humans. It infects the intestines causing ulceration, and symptoms including diarrhoea, cramps, fever and weight loss. If untreated, the amoeba can move to the liver and other organs, and the infection can prove fatal. The disease is endemic in regions with poor sanitation. The parasites are passed in faeces, and can survive outside the body as long-lasting cysts, which revert to the active trophozoite stage when ingested. Treatment is with antimicrobial drugs.