Expanding the etiologic spectrum of spastic ataxia syndrome: chronic infection with human T lymphotropic virus type 1.

Human T-lymphotropic virus type-1 (HTLV-1) is a neglected infection most often associated with an indolent process. However, a subset of HTLV-1 seropositive patients face the risk to develop life-threatening T-cell lymphoma/leukemia, or the highly disabling and incurable HTLV1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Over the years, other complications to HTLV-1 have been proposed and debated intensely.