Professor of Medicine
Senior Investigator of the Oswaldo Cruz Foundation
Title: Reappraisal of Morbidity Related to HTLV-1
Biography: Edgar M. Carvalho
The HTLV-1 infection has been neglected mainly due to the misconception it is a low morbidity virus infection, as HTLV-1 associated myelopathy (HAM) and adult T cell leukemia, occurs in less than 5% of infected patients. In a cohort of 495 HTLV-1 infected individuals followed for up to 18 years we have determined the frequency and pathogenesis of diseases associated to HTLV-1. Patients were classified in 4 groups: 1) HTLV-1 carriers; 2) Neurogenic bladder and/or erectile dysfunction; 3) Definitive HAM/TSP; 4) Other inflammatory diseases. The diagnosis was performed by detection of anti HTLV-1 antibodies by ELISA and confirmed by Western blot. The pro-viral load was measured by RT-PCR and cytokine levels in supernatants of unstimulated lymphocyte cultures by ELISA. While there was an association between increase in pro-inflammatory cytokines and pro-viral load (PVL) with HAM, and at lesser extension with neurogenic bladder, these variables were not correlated with other inflammatory diseases related to the virus. The sicca syndrome was associated with high PVL in saliva and gland atrophy. The patients with chronic periodontitis had HTLV-1 in the periodont, increased expression of pro-inflammatory cytokines in this tissue and down modulation of anti-inflammatory cytokines. HTLV-1 associated arthropathy was characterized by pain in large joints, absence or little synovitis, entesitis detected by X-ray and no association with PVL or pro-inflammatory cytokines levels.
More than 95% of these patients who present neurogenic bladder or erectile dysfunction did not progress to HAM/TSP. Morbidly related to HTLV-1 is observed in more than 50% of infected subjects and is related to virus migration to specific tissues associated with a systemic or local exaggerated inflammatory response.