[Human T-lymphotrophic virus type I and II--diagnosis and clinical presentation]

Human T-lymphotropic virus type 1, HTLV-I, was the first human oncogenic retrovirus to be isolated in 1978. HTLV-I has previously been called Human T-cell leukaemia virus or Human T-cell lymphoma virus type I. HTLV-I infection is endemic in southwestern Japan, the Caribbean basin, and parts of South America and Africa. HTLV-I is aetiologically associated with adult T-cell leukaemia lymphoma and tropical spastic paraparesis (TSP), also known as HTLV-I-associated myelopathy. HTLV-II was isolated in 1982 and is endemic among some north American Indians. HTLV-II has not been clearly linked to any specific disease. Both viruses are found worldwide, particularly among intravenous drug users (IVDU), and have also been found in blood donors in USA and Europe. HTLV-I/II are transmitted by the same routes as HIV-1: blood-borne via blood transfusions and among IVDUs by sharing contaminated needles, and by mother-to-child transmission, primarily through breast feeding. HTLV-I/II infections are also sexually transmitted and can be transmitted in utero, though less efficiently than HIV-1. The diagnosis of HTLV-I/II infections is based on the detection of antibody to the virus. Due to the high degree of cross reactivity between HTLV-I and HTLV-II, it is difficult by serology to discriminate between the two viruses. Less than 5% of individuals infected with HTLV-I develop symptoms after a latent period, which can last from a few years to several decades. No specific treatment of adult T-cell leukaemia or tropical spastic paraparesis is currently available and no vaccine has yet been developed.