Chemotherapy of Amoebiasis It is caused by Entamoeba Histolytica. It is exists in two forms: The trophozoites, present in the intestinal lumen & in infected tissues. The cysts form which develop from trophozoites within intestinal lumen. The trophozoites with amoeboid movements are active form and rapidly dies after elimination in the stool. The cysts represent a dormant stage and are resistant to freezing and partial drying and transmit infection from person to person. Primarly it affects colon, later liver, lung, & brain.