title: Transfusion-transmitted Babesia microti identified through hemovigilance.
abstract: BACKGROUND
  Babesia microti, the primary cause of human babesiosis in the United States, is an intraerythrocytic parasite endemic to the Northeast and upper Midwest. Published studies indicate that B. microti increasingly poses a blood safety risk. The American Red Cross Hemovigilance Program herein describes the donor and recipient characteristics of suspected transfusion-transmitted B. microti cases reported between 2005 and 2007.
  
  
  METHODS
  Suspected transfusion-transmitted Babesia infections were reported by transfusion services or were discovered through recipient-tracing investigations of prior donations from donors with a positive test for B. microti in a serologic study. Follow-up samples from involved donors were tested by Babesia-specific immunofluorescence assay, Western blot, and/or real-time polymerase chain reaction analysis.
  
  
  RESULTS
  Eighteen definite or probable B. microti infections, including five fatalities, were identified in transfusion recipients, 16 from hospital-reported cases and two through serologic lookback studies. Thirteen recipients were 61 to 84 years old and two were 2 years old or younger. Two recipients had sickle cell disease and four were known to be asplenic, including one with sickle cell disease. Seventeen antibody-positive donors were implicated; 11 (65%) were residents in Babesia-endemic areas, while four (24%) nonresident donors had a history of travel to endemic areas.
  
  
  CONCLUSIONS
  Transfusion-transmitted B. microti can be a significant cause of transfusion-related morbidity and mortality, especially in infant, elderly, and asplenic blood recipients. These data demonstrate the need for interventions, in both endemic and nonendemic areas of the United States, to reduce patient risk.
authors.affiliation: Transmissible Diseases Department, Jerome H. Holland Laboratory, American Red Cross, Rockville, Maryland 20855, USA. tonnettil@usa.redcross.org
authors.forename: Laura
authors.initials: L
authors.lastname: Tonnetti
authors.forename: Anne F
authors.initials: AF
authors.lastname: Eder
authors.forename: Beth
authors.initials: B
authors.lastname: Dy
authors.forename: Jean
authors.initials: J
authors.lastname: Kennedy
authors.forename: Patricia
authors.initials: P
authors.lastname: Pisciotto
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Benjamin
authors.forename: David A
authors.initials: DA
authors.lastname: Leiby
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D041001:Babesia microti / Q000235:genetics / Q000302:isolation & purification*; D001404:Babesiosis / Q000175:diagnosis / Q000401:mortality / Q000635:transmission; D001771:Blood Banks; D001782:Blood Donors / Q000706:statistics & numerical data; D002675:Child, Preschool; D016054:DNA, Protozoan / Q000032:analysis; D018562:Disease Transmission, Infectious; D019353:Endemic Diseases / Q000706:statistics & numerical data; D017707:Erythrocyte Transfusion / Q000009:adverse effects* / Q000401:mortality*; D006801:Humans; D007231:Infant, Newborn; D008875:Middle Aged; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D016054:DNA, Protozoan