Accepted Article This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/tmi.13278 This article is protected by copyright. All rights reserved. Systematic Review Human T-cell Lymphotropic Virus type 1 and Associated Diseases in Latin America Emiliana Eusebio-Ponce 1,2 , Francisco Javier Candel 2,3 , Eduardo Anguita 2,4 1 Research Department, Universidad Iberoamericana, Santo Domingo, Dominican Republic 2 Department of Medicine, Universidad Complutense de Madrid, Spain 3 Clinical Microbiology and Infectious Diseases Department, Instituto de Medicina de Laboratorio, Hospital Clínico San Carlos, Madrid, Spain 4 Hematology Department, Instituto de Medicina de Laboratorio, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos, Madrid, Spain SUMMARY This narrative review, which is based on a after a systematic literature search following the PRISMA guidelines, provides a general overview of Human T-cell Lymphotropic Virus type 1 (HTLV-1) and associated diseases: Adult T-cell Leukemia-Lymphoma (ATLL) and HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) in Latin America, focusing on epidemiology and prevention. Using the published information on HTLV-1, ATLL and HAM/TSP prevalence, we present comprehensive and accurate maps and tables, and developed an algorithm to assist in the prevention of HTLV-1 transmission through breastfeeding while considering socioeconomic status. Latin America is an interesting scenario to study HTLV-1 because of the diverse origin of its population. Apart from the expected high prevalence in inhabitants of African ancestry, the presence of endemic foci affecting indigenous populations is particularly striking. ATLL prevention is the biggest challenge in this field. Most ATLL cases are transmitted through breastfeeding; thus, prevention methods to avoid ATLL in endemic countries have to be focused on this. In view of the high inequality in most Latin American countries, reduction of breastfeeding duration, freezing/thawing and pasteurization of breast milk can be suitable interventions in poor settings, considering that avoiding the risk of malnutrition and infant mortality must be the priority.