Conclusions: Higher seroprevalence in rural population was attributable to a higher probability to encounter the vector in rural areas. Increased exposure to infection and to development of the disease symptoms together with increased lethality of the disease as patients age explains the age-related Chagasic electrocardiographic anomalies. Since rural and urban populations showed different reactions under Chagas disease and the rural population was mainly of guarani stock, the genetic and environmental determinants of the results should be further explored. (C) 2021 The Authors. Published by Elsevier Ltd on behalf of World Federation of Parasitologists.