title: Estimated risk of Chikungunya viremic blood donation during an epidemic on Reunion Island in the Indian Ocean, 2005 to 2007.
abstract: BACKGROUND
  Between 2005 and 2007, Chikungunya virus (CHIKV) caused a massive epidemic on Reunion Island with a major peak in the number of cases in February 2006. Blood donation was interrupted on the island in January 2006.
  
  
  METHODS
  Estimates of the mean risk of viremic blood donation on Reunion Island were computed for different phases of the epidemic. Calculations used CHIKV incidence estimates derived from sentinel surveillance, duration of viremia, and frequency of asymptomatic infection. Data on these two last parameters were initially based on hypotheses and subsequently obtained from studies carried out during the outbreak. The estimated risk was compared to the results of CHIKV nucleic acid testing (NAT) implemented for platelet (PLT) donations screening.
  
  
  RESULTS
  Over the course of the outbreak, the mean risk was estimated at 132 per 100,000 donations. The risk peaked at 1,500 per 100,000 donations at the height of the outbreak in February 2006. In total, 47 blood donations would have been potentially viremic if blood collection had not been interrupted. During this period, an estimated 312,500 of 757,000 inhabitants had been infected by mosquito-borne transmission. From January to May 2006, the estimated mean risk (0.7%) and observed risk on PLT donations (0.4%) were of the same order of magnitude.
  
  
  CONCLUSIONS
  During this large outbreak, the estimated risk of viremic blood donation was high, but low compared to the risk of mosquito-borne CHIKV transmission. The estimated risk was corroborated by the concordant results with the observed risk.
authors.affiliation: The Institut de Veille Sanitaire (InVS) (French Institute of Public Health Surveillance), Saint-Maurice, France. c.brouard@invs.sante.fr
authors.forename: Cécile
authors.initials: C
authors.lastname: Brouard
authors.forename: Pascale
authors.initials: P
authors.lastname: Bernillon
authors.forename: Isabelle
authors.initials: I
authors.lastname: Quatresous
authors.forename: Josiane
authors.initials: J
authors.lastname: Pillonel
authors.forename: Azzedine
authors.initials: A
authors.lastname: Assal
authors.forename: Henriette
authors.initials: H
authors.lastname: De Valk
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Desenclos
mesh_terms: D018354:Alphavirus Infections / Q000453:epidemiology / Q000209:etiology / Q000821:virology*; D001782:Blood Donors; D002646:Chikungunya virus / Q000302:isolation & purification*; D004196:Disease Outbreaks / Q000517:prevention & control / Q000706:statistics & numerical data*; D006801:Humans; D019156:Indian Ocean; D017508:Reunion / Q000453:epidemiology; D012621:Seasons; D065227:Transfusion Reaction; D014766:Viremia / Q000453:epidemiology / Q000821:virology*