[Clinical and biological epidemiology of onco-retroviral HTLV-I and II infections].

Human T cell leukemia virus type I and II are endemic in South West Japan and in large parts of the equatorial belt in Central and South America, in Africa, and in some Pacific islands, areas where 1 to 5% of the general populations are infected. Pockets of high prevalence up to 15% and even 35% can be observed. The transmission of HTLV-I includes: maternal to offspring through breast feeding, sexual mainly from men to women and through blood exchange (blood transfusion, intravenous drug abusers, etc.) The diseases being proven to be caused by HTLV-I, include acute adult T cell leukemias as described in Japan, in 1977, in which the HTLV-I provirus is clonally integrated in leukemic cells, and a progressive spastic encephalomyelopathy named TSP/HAM, frequent in HTLV-I endemic areas, and in which an active viral replication takes place. No specific treatment being available, vaccine development, more feasible than for HIV, is critical since 8 to 12% of seropositive individuals develop HTLV-I associated diseases.