Human T-lymphotropic virus type II and neurological disease

Authors

  • Abelardo Araujo MD,

    1. Evandro Chagas Clinical Research Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
    2. Conway Institute of Biomolecular and Biomedical Research, Department of Medical Microbiology, University College Dublin, Belfield, Dublin, Ireland
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  • William W. Hall MD

    Corresponding author
    1. Conway Institute of Biomolecular and Biomedical Research, Department of Medical Microbiology, University College Dublin, Belfield, Dublin, Ireland
    • Conway Institute of Biomolecular and Biomedical Research, Department of Medical Microbiology, University College Dublin, Belfield, Dublin 4, Ireland
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Abstract

Human T-lymphotropic virus type I (HTLV-I) and type II (HTLV-II) are closely related retroviruses with similar biological properties and common modes of transmission. HTLV-I infection is endemic in well-defined geographic regions, and it is estimated that some 20 million individuals are infected worldwide. Although most infected individuals are asymptomatic carriers, some 2 to 5% will develop a chronic encephalomyelopathy, HTLV-I–associated myelopathy/tropical spastic paraparesis (HAM/TSP). In contrast with HTLV-I, the role of HTLV-II in the development of neurological disorders is much less clear. HTLV-II is endemic in many native Amerindian groups and epidemic in injecting drug users (IDUs) worldwide. To evaluate the role of HTLV-II in neurological disease, we have critically reviewed all reported cases of HTLV-II–associated disorders. This has confirmed that although rare infection is associated with a disorder clinically similar or identical to HAM/TSP. However, most reports that have attributed infection to a range of other neurological disorders are difficult to evaluate in that in many cases either the association appears to be fortuitous or the presentations were confounded by a background of concomitant human immunodeficiency virus–1 infection and/or active IDU. In view of the many HTLV-II–infected individuals in urban areas of North America and Europe, neurologists should be aware of the potential clinical consequences of this infection.

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