[Human T lymphotropic virus: from molecular epidemiology to disease]

Human T lymphotropic virus (HTLV) is a retrovirus presenting several novel features. Although the dominant modes of transmission are conventional, i.e., blood-borne, sexual and mother-to-child, HTLV), the distribution of HTLV infection is highly variable within human populations. Unlike HIV, the genome of HTLV shows low variability but, like HIV, HTLV originates from old world monkeys and apes. Although the virus can induce severe diseases, this course is observed in only a small number of infected people. Determinant factors for development of adult T cell leukemia (ATL) and tropical spastic paraparesis (TSP) are complex and treatment outcomes have been disappointing.