title: Decline in prevalence and asymmetric distribution of human T cell lymphotropic virus 1 and 2 in blood donors, State of Minas Gerais, Brazil, 1993 to 2007.
abstract: BACKGROUND
  Human T cell lymphotropic virus types 1 and 2 (HTLV-1/2) are endemic in Brazil and are screened for in transfusion services since 1993. This study evaluated the evolution of the prevalence of HTLV-1 and 2 in blood donors of the Hemominas Foundation from 1993 to 2007, and its geographical distribution in State of Minas Gerais, Brazil.
  
  
  METHODS
  The Hemominas Foundation is a centralized blood center in Minas Gerais, Brazil. The sources of data were the Hemominas Foundation Technical Bulletin and files from the centralized serological laboratory. Donors were tested in the period using enzyme linked immuno sorbent assays (ELISA), followed by Western blot, when repeatedly reactive. The data were analyzed by EPIINFO 6.2 and TABWIN 3.5 softwares.
  
  
  RESULTS
  The average seroprevalence in the period 1993-2007 was 0.1%. A steady decline occurred from 0.4% in 1993 to below 0.1% in 2002 and later, with a transient peak of 0.5% in 1994. HTLV reactivity distribution was asymmetrical in the state, with regions of higher prevalence, interspersed with low prevalence areas. Comparison of positive and negative donors verified that increasing age was proportional to virus positivity. Odds ratio for age ranged from 1.43 (30 to 39 years-old) to 3.09 (50 to 65 years-old). Women had a greater chance of being positive (OR-1.64), as previously described.
  
  
  CONCLUSIONS
  Possible explanations for HTLV-1/2 prevalence decline are the exclusion of positive donors from the donor pool, an increase in repeat donors and ELISA test improvement, with reduction in the number of false positive results.
authors.affiliation: Technical Management, Hemocenter of Belo Horizonte, Belo Horizonte, MG.
authors.forename: Maria Regina
authors.initials: MR
authors.lastname: Dias-Bastos
authors.forename: Cláudia Di Lorenzo
authors.initials: CD
authors.lastname: Oliveira
authors.forename: Anna Bárbara de Freitas
authors.initials: AB
authors.lastname: Carneiro-Proietti
mesh_terms: D000328:Adult; D001782:Blood Donors / Q000706:statistics & numerical data*; D015153:Blotting, Western; D001938:Brazil / Q000453:epidemiology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005843:Geography; D015490:HTLV-I Infections / Q000175:diagnosis / Q000453:epidemiology*; D015491:HTLV-II Infections / Q000175:diagnosis / Q000453:epidemiology*; D015368:Human T-lymphotropic virus 1 / Q000276:immunology*; D015367:Human T-lymphotropic virus 2 / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence