title: Seroprevalence of Babesia microti infection in Canadian blood donors.
abstract: BACKGROUND
  Human babesiosis, caused by the intraerythrocytic protozoan parasite Babesia microti, is primarily transmitted by tick bites and is also transmitted by transfusion. Infections have been identified in U.S. blood donors close to Canadian borders. We aimed to assess the risk of transfusion-transmitted babesiosis in Canada by examining infections in ticks and seroprevalence in blood donors.
  
  
  METHODS
  Passive surveillance (receipt of ticks submitted by the public) was used to identify regions for tick drag sampling (active surveillance, 2009-2014). All ticks were tested for B. microti using an indirect immunofluorescent antibody assay (Imugen, Inc.). Between July and December 2013, blood donations from selected sites (southern Manitoba, Ontario, Québec, New Brunswick, and Nova Scotia) near endemic U.S. regions were tested for antibody to B. microti. Donors completed a questionnaire about risk travel and possible tick exposure.
  
  
  RESULTS
  Of approximately 12,000 ticks submitted, 14 were B. microti positive (10 in Manitoba, one in Ontario, one in Québec, two in New Brunswick). From active tick surveillance, six of 361 ticks in Manitoba were positive (1.7%), three of 641 (0.5%) in Québec, and none elsewhere. There were 26,260 donors at the selected sites of whom 13,993 (53%) were tested. None were positive for antibody to B. microti. In 2013, 47% of donors visited forested areas in Canada, and 41% traveled to the United States.
  
  
  CONCLUSIONS
  The data do not suggest that laboratory-based testing is warranted at this time. However, there are indicators that B. microti may be advancing into Canada and ongoing monitoring of tick populations and donor seroprevalence is indicated.
authors.affiliation: Canadian Blood Services, Ottawa, Ontario, Canada.
authors.forename: Sheila F
authors.initials: SF
authors.lastname: O'Brien
authors.affiliation: Héma-Québec, Montreal, Québec, Canada.
authors.forename: Gilles
authors.initials: G
authors.lastname: Delage
authors.affiliation: Canadian Blood Services, Ottawa, Ontario, Canada.
authors.forename: Vito
authors.initials: V
authors.lastname: Scalia
authors.affiliation: Public Health Agency of Canada, Winnipeg, Manitoba, Canada.
authors.forename: Robbin
authors.initials: R
authors.lastname: Lindsay
authors.affiliation: Héma-Québec, Montreal, Québec, Canada.
authors.forename: France
authors.initials: F
authors.lastname: Bernier
authors.affiliation: Héma-Québec, Montreal, Québec, Canada.
authors.forename: Sophie
authors.initials: S
authors.lastname: Dubuc
authors.affiliation: Héma-Québec, Montreal, Québec, Canada.
authors.forename: Marc
authors.initials: M
authors.lastname: Germain
authors.affiliation: Canadian Blood Services, Ottawa, Ontario, Canada.
authors.forename: Gerry
authors.initials: G
authors.lastname: Pilot
authors.affiliation: Canadian Blood Services, Ottawa, Ontario, Canada.
authors.forename: Qi-Long
authors.initials: QL
authors.lastname: Yi
authors.affiliation: Canadian Blood Services, Ottawa, Ontario, Canada.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Fearon
mesh_terms: D000818:Animals; D041001:Babesia microti / Q000302:isolation & purification*; D001404:Babesiosis / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission; D001782:Blood Donors / Q000706:statistics & numerical data*; D058731:Blood Safety; D002170:Canada / Q000453:epidemiology; D006801:Humans; D018884:Ixodes / Q000469:parasitology*; D018570:Risk Assessment; D012307:Risk Factors; D016036:Seroepidemiologic Studies