Núcleos familiares infectados pelo vírus linfotrópico decélulas T humanas: determinantes epidemiológicos e genéticos (Belo Horizonte, 1997-2005)

Abstract

The review of epidemiologic aspects of human T-lymphotropic virus type I let us to assess where we are. We know well about the geographic distribution of the virus and its trend to clustering; we understood the major modes of transmission and the HTLVs causative role in major disease association (adult T cell leukemia-ATL and HTLV associated myelopathy- TSP/HAM). But we still have a long way to run in search of other answers and more and better studies are needed for other apparent disease outcomes, to clarify pathogenesis and on the promoting / inhibition factors that could explain why the great majority of infected subjects remains health carriers. The high prevalence rates found in the family studies point to family aggregation of infection, leading us to look for other distant factors (environmental? genetic?) that could contribute to this, and underline the importance of screening test for infected individual relatives and sexual partner, in order to detain HTLV silent dissemination. HTLV type II is less prevalent than type I in Brazil, but is often found among UDI and American native population. We found a family infected with HTLV-ll among a seropositive former blood donors cohort and this challenge us to molecular studies. The results point tovertical and horizontal transmission of the virus. These modes of transmission are well defined to HTLV-I but some doubts persist for type II, according some researches. The major question related to HTLV keeps going why the great majority remains as health carriers. Japanese researches report the importance of the individual immune responseconditioning the outcome in infected people. Since the efficiency of the immune answer is established by the HLA alleles, we decide to type some infected families. There were found similarities and differences among Japanese and Brazilian studies, and these results suggestHLA alleles could not control alone the disease outcome in the infected individuals. Since there is not curative treatment of ATL and HAM/TSP and a vaccine is unavailable, the social and financial cost for the individual, his/her family and the health system is immense. For this reason, public health interventions aimed at counseling and educating high riskindividuals and populations are of paramount importance.