 Patients and Methods. Patients selected to be enrolled were born in Chagas disease endemic areas of Argentina and bordering countries such as Bolivia and Paraguay, whose current residence is in urban non endemic areas of Argentina. They were sorted by clinical stage: stage 0, 1, 2 and 3 according to a modified Kuschnir classification.1 Briefly, Stage 0 corresponds to patients only with reactive serology for Chagas disease; stage 1, patients with reactive serology plus electrocardiographic abnormalities; stage 2, patients with the abovementioned characteristics plus dilatation of left ventricle by echocardiography, and stage 3, patients with the abovementioned characteristics, plus cardiac failure. 