Brain magnetic resonance imaging white matter lesions are frequent in HTLV-I carriers and do not discriminate from HAM/TSP.

Human T lymphotropic virus (HTLV)-I is known to cause HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and other pronounced disease in less than 4% of those infected. However, evidence is accumulating that a proportion of HTLV-I carriers have neurological and urological symptoms without fulfilling criteria for HAM/TSP. Brain white matter (WM) lesions on magnetic resonance imaging (MRI) are frequently seen in HAM/TSP.