title: Diversity and origin of hepatitis C virus infection among unpaid blood donors in the Netherlands.
abstract: BACKGROUND
  To improve transfusion policy and to increase understanding of the spread of hepatitis C virus (HCV) in the general population, HCV infections among voluntary Dutch blood donors were examined with molecular epidemiologic techniques.
  
  
  METHODS
  During 6 years, 1997 through 2002, confirmed anti-HCV-positive donors were interviewed on HCV-associated risk behavior with a standardized questionnaire. Additionally, HCV isolates were genotyped, partially sequenced, and compared to sequences obtained from Dutch injecting drug users (IDUs).
  
  
  RESULTS
  HCV prevalence and incidence rates among Dutch donors were extremely low; the residual risk of transmitting HCV was calculated to be 1 in 30 million donations. Former IDUs (21%), transfusion recipients (30%), and immigrants (>12%) were identified as major HCV risk groups. Cryptogenic transmission caused 18 percent of infections among new donors and all infections among repeat donors. Compared to IDUs, genotype distribution among donors was highly diverse; major subtypes were 3a (27%), 1a (24%), 1b (24%), 2a/b (10%), and 4 (9%). Half of the donors were infected with IDU-related subtypes 1a and 3a, whereas subtype 1b mainly spread via blood transfusion and various other nosocomial modes of transmission in the past. HCV infections acquired in endemic countries could be clearly identified based on genotype.
  
  
  CONCLUSIONS
  Different modes of transmission are linked to infections with certain HCV subtypes, suggesting separate HCV epidemics, but spillover between different risk groups underlines the value of molecular epidemiologic techniques to gain insight into the origin and dynamics of HCV infections on a population level.
authors.affiliation: Department of Infectious Diseases, Health Service, Amsterdam, The Netherlands. tvdlaar@ggd.amsterdam.nl
authors.forename: Thijs J W
authors.initials: TJ
authors.lastname: van de Laar
authors.forename: Marco H G M
authors.initials: MH
authors.lastname: Koppelman
authors.forename: Akke K
authors.initials: AK
authors.lastname: van der Bij
authors.forename: Hans L
authors.initials: HL
authors.lastname: Zaaijer
authors.forename: H Theo M
authors.initials: HT
authors.lastname: Cuijpers
authors.forename: Cees L
authors.initials: CL
authors.lastname: van der Poel
authors.forename: Roel A
authors.initials: RA
authors.lastname: Coutinho
authors.forename: Sylvia M
authors.initials: SM
authors.lastname: Bruisten
mesh_terms: D000328:Adult; D001782:Blood Donors; D001803:Blood Transfusion; D005260:Female; D016679:Genome, Viral / Q000235:genetics; D016174:Hepacivirus / Q000235:genetics; D006526:Hepatitis C / Q000453:epidemiology* / Q000235:genetics / Q000635:transmission*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology / Q000379:methods; D009426:Netherlands; D012189:Retrospective Studies; D012307:Risk Factors; D015819:Substance Abuse, Intravenous / Q000453:epidemiology / Q000821:virology