Human T cell lymphotropic virus (HTLV-1): when to suspect infection?

Human T-cell lymphotropic virus (HTLV) infections have occurred for thousands of years. However, knowledge about their pathogenesis is recent. The virus is endemic in several regions around the world. In Brazil, it is present in all states at varying prevalence rates and it has been estimated that around 2.5 million Brazilians are infected. Genetic and immunological parameters of the host are the most important determinants of the clinical manifestations associated with infection. These can be divided into three categories: neoplastic, inflammatory and infectious. HTLV-associated myelopathy (HAM/TSP) and adult T-cell leukemia/lymphoma (ATLL) were the first diseases to be related to this retrovirus. More recently, countless other diseases have been correlated with the virus. The objective of this review is to provide an update on epidemiological, pathophysiologic, therapeutic and, primarily, diagnostic knowledge about HTLV, in order to encourage etiologic suspicion of HTLV in all its diverse clinical manifestations, which are currently rarely associated with this agent.