ABSTRACT
I. INTRODUCTION Human T-cell lymphotropic virus type I (HTLV-I) is known as the causative agent for adult T-cell leukemia (ATL). This same virus was found to be related to another human disease, a progressive spastic paraparesis, found independently in two areas of the world, the Caribbean basin and Japan. In the Caribbean basin, 59% of patients with tropical spastic paraparesis (TSP) had antibodies to HTLV-I [1]. In Japan, a high prevalence of primary lateral sclerosis or spinal spastic paraparesis was found in South Kyushu [2]. A follow-up study of this disorder established the existence of a new disease associated with HTLV-I, which was named HTLV-I associated myelopathy (HAM) [3-5]. The disease is now known under the acronym HAM/TSP [6,7].
