In the acute phase of Chagas disease the nests of Trypanosoma cruzi amastigote forms are found in tissues, especially in cardiac, skeletal and smooth muscle cells from human body. However the most important element of severe injuries formation in the heart and digestive tube tissues is the lymphocyte and macrophage cells infiltration triggering the destruction of normal, non-parasitized heart muscles, and ganglia from the intestine and peripheral nervous system. The non-parasitized target cells destruction caused by lymphocytes and macrophages from the immune system is particularly evident during the chronic phase of the chagasic infection. The severe inflammation weakens the organs, leading to dilatation and to insufficiency. The cellular death implies in replacement by fibrous scars which are only a sequelae from the rejection of the “self” tissue.