Le rétrovirus humain oncogène HTLV-1 : épidémiologie descriptive et moléculaire, origine, évolution et aspects diagnostiques et maladies associées Human retrovirus HTLV-1: descriptive and molecular epidemiology, origin, evolution, diagnosis and associated diseases

Human T-cell leukemia/lymphoma virus type 1 (HTLV-1) was the first oncogenic human retrovirus discovered in 1980. It is estimated that around 10–20 million people are infected with HTLV-1 worldwide. However, HTLV-1 is not a ubiquitous virus. Indeed, HTLV-1 is present throughout the world with clusters of high endemicity including mainly southern Japan, the Caribbean region, parts of South America and intertropical Africa, with foci in the Middle East and Australia. The origin of this puzzling geographical repartition is probably linked to a founder effect in certain human groups. In the high endemic areas, 0.5 to 50% of the people have antibodies against HTLV-1 antigens. HTLV-1 seroprevalence increases with age, especially in women. HTLV-1 has 3 modes of transmission: mother to child, mainly through prolonged breastfeeding (> 6 months); sexual, mainly but not exclusively occurring from male to female; and by blood products contaminated by infected lymphocytes. HTLV-1 is mainly the etiological agent of two very severe diseases: a malignant T CD4+ cell lymphoproliferation of very poor prognosis, named adult T-cell leukemia/lymphoma (ATLL), and a chronic neuro-myelopathy named tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM). HTLV-1 is also associated with rare anterior uveitis, infective dermatitis and myositis in some high HTLV-1 endemic areas. The repartition of the different molecular subtypes or genotypes is mainly linked to the geographical origin of the infected persons but not to the associated pathology. HTLV-1 possesses a remarkable genetic stability probably linked to viral amplification via A. Gessain (*) Unite d’epidemiologie et physiopathologie des virus oncogenes, departement de virologie, CNRS-URA3015, Institut Pasteur, 28, rue du Docteur-Roux, F-75724 Paris cedex 15, France e-mail : antoine.gessain@pasteur.fr CNRS, URA3015, F-75015 Paris, France Bull. Soc. Pathol. Exot. DOI 10.1007/s13149-011-0174-4