Infection caused by Entamoeba histolytica, of Entamoeba group is called amoebiasis. It is also called amoebic dysentery. The causative agent is an anerobic protozoan parasite that can exist for extended stretches of time in the colon. These can eb present in the digestive system with no or mild symptoms. Symptoms may include ulcerations, diarrhea or bloody diarrhea.