title: Determination of Babesia microti seroprevalence in blood donor populations using an investigational enzyme immunoassay.
abstract: BACKGROUND
  Transfusion-transmitted babesiosis caused by Babesia microti has emerged as a significant risk to the US blood supply. This study estimated the prevalence of B. microti antibodies in blood donors using an investigational enzyme immunoassay (EIA).
  
  
  METHODS
  A peptide-based EIA that detects both immunoglobulin (Ig)G and IgM antibodies to B. microti was developed and validated. Donor samples randomly selected from areas defined as high-risk endemic, lower-risk endemic, and nonendemic for B. microti were deidentified and tested using the investigational EIA. Samples that were EIA repeat reactive were further tested by B. microti immunofluorescent assay (IFA), polymerase chain reaction (PCR) on red blood cell lysates, and peripheral blood smear examination. A random subset of 1272 samples from high-risk endemic areas was tested by IFA, PCR, and peripheral blood smear in parallel with EIA.
  
  
  RESULTS
  Among 15,000 donations tested with the investigational B. microti EIA, EIA repeat-reactive rates were 1.08% (54/5000) in a high-risk endemic area, 0.74% (37/5000) in a lower-risk area, and 0.40% (20/5000) in a nonendemic area. After application of a revised cutoff, these values were reduced to 0.92%, (46/5000), 0.54% (27/5000), and 0.16% (8/5000). Overall concordance between EIA and IFA among donor samples was 99.34%. One seropositive sample was positive by PCR.
  
  
  CONCLUSIONS
  The seroprevalence of B. microti in blood donors in a high-risk area measured by an investigational EIA was approximately 1%. The EIA shows promise as an efficient high-throughput blood donor screening assay for B. microti.
authors.affiliation: Immunetics, Inc., Boston, Massachusetts.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Levin
authors.forename: Phillip C
authors.initials: PC
authors.lastname: Williamson
authors.forename: James L
authors.initials: JL
authors.lastname: Erwin
authors.forename: Sherri
authors.initials: S
authors.lastname: Cyrus
authors.forename: Evan M
authors.initials: EM
authors.lastname: Bloch
authors.forename: Beth H
authors.initials: BH
authors.lastname: Shaz
authors.forename: Debra
authors.initials: D
authors.lastname: Kessler
authors.forename: Sam R
authors.initials: SR
authors.lastname: Telford
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Krause
authors.forename: Gary P
authors.initials: GP
authors.lastname: Wormser
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Ni
authors.forename: Haihong
authors.initials: H
authors.lastname: Wang
authors.forename: Neil X
authors.initials: NX
authors.lastname: Krueger
authors.forename: Sally
authors.initials: S
authors.lastname: Caglioti
authors.forename: Michael P
authors.initials: MP
authors.lastname: Busch
mesh_terms: D000913:Antibodies, Protozoan / Q000097:blood; D041001:Babesia microti / Q000276:immunology / Q000302:isolation & purification*; D001404:Babesiosis / Q000097:blood* / Q000469:parasitology*; D001782:Blood Donors / Q000706:statistics & numerical data*; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods*; D016036:Seroepidemiologic Studies; D065227:Transfusion Reaction
chemical_list: D000913:Antibodies, Protozoan