Entamoeba histolytica is an amoeba responsible for the gastrointestinal disease amebic dysentery. While E. histolytica is found in the environment as both an active trophozoite and as an inactive cyst, virtually all cases of amebic dysentery can be traced to infection with the cyst form of the organism. Speculate on why the active form of the pathogen causes far fewer cases of disease. Solution Mature cysts are more resistant to atmosphere as well as for antibiotics and Immune system than mature organism, upon ingestion of active form of organism which gets killed while if mature cyst enters the human body it remains as it is and later it develops to an active organism which can cause actual disease..