[Human T-lymphotropic virus type I (HTLV-I): risk of transmission with transfusion]

PATHOGENIC ROLE: The human T-lymphotropic virus type I (HTLV-I), the first human retrovirus discovered, is the etiologic agent of adult T-cell leukemia/lymphoma (ATL) and of HTLV-I associated myelopathy or tropical spastic paraparesis (HAM/TSP) and has a widespread but uneven worldwide distribution. HTLV-I has a high seroprevalence in Southern Japan, the Caribbean basin and Sub-Sahara Africa. Blood transfusion, intravenous drug use, breast feeding and sexual contacts are major routes of contamination. IMPLICATIONS FOR BLOOD TRANSFUSION: The screening of blood donors for antibody to HTLV-I became systematic in 1989 in French West Indies and in 1991 in Continental France. This review deals with the transfusional implications of the HTLV-I, which belongs to the group of the blood-borne viruses: the prevalence of transfusion-linked HTLV-I infection before the implementation of the specific preventive measures, the parameters influencing the risk of transfusional contamination (the type of blood products, the age of the blood product with regards to its collection date, the proviral load of the blood donor), the prognosis of HTLV-I infection in patients contaminated by transfusion, the prophylactic strategies of transfusion contamination and the residual risk of infection through HTLV-I-infected risk blood products.