title: Evaluation of a new enzyme-linked immunosorbent assay for detection of Chagas antibody in US blood donors.
abstract: BACKGROUND
  Chagas disease, caused by the parasite Trypanosoma cruzi, represents a serious blood safety problem due to increasing immigration from Latin America. The Food and Drug Administration recently recommended implementation of Chagas antibody screening for US donors as soon as a suitable assay is licensed. An anonymized preclinical study of a prototype T. cruzi lysate-based enzyme-linked immunosorbent assay (ELISA) developed by Ortho-Clinical Diagnostics was conducted.
  
  
  METHODS
  Two populations of specimens were evaluated: 1) 10,192 sequential donations from blood donors residing in the El Paso, Texas, area and 2) 178 specimens from South America which were presumptively positive for antibodies to T. cruzi and purchased from commercial vendors.
  
  
  RESULTS
  A total of 10,189 (99.97%) of the 10,192 screened donor specimens did not react, whereas 3 (0.03%) tested initially reactive. The 3 initially reactive specimens tested repeat reactive and were confirmed by radioimmunoprecipitation analysis (RIPA). Based on antibody profile analysis, 2 of the 3 Chagas-positive specimens were from the same donor. Observed specificity of the test was therefore 100 percent. Of the specimens from South America, 173 of 178 were reactive by the prototype ELISA. Of the 5 nonreactive specimens, all did not react by indirect fluorescence assay, but 4 were positive by RIPA. Therefore, calculated sensitivity of the ELISA was 97.7 percent (173/177).
  
  
  CONCLUSIONS
  These studies indicate that the prototype ELISA has excellent sensitivity and specificity for detection of antibodies to T. cruzi in donors. Moreover, among donations from a geographically selected collection region of the United States, observed seroprevalence was 0.03 percent.
authors.affiliation: Blood Systems Research Institute, San Francisco, California 94118, USA. ltobler@bloodsystems.org
authors.forename: Leslie H
authors.initials: LH
authors.lastname: Tobler
authors.forename: Paul
authors.initials: P
authors.lastname: Contestable
authors.forename: Lubov
authors.initials: L
authors.lastname: Pitina
authors.forename: Lubor
authors.initials: L
authors.lastname: Pitina
authors.forename: Holly
authors.initials: H
authors.lastname: Groth
authors.forename: Shirley
authors.initials: S
authors.lastname: Shaffer
authors.forename: Gary R
authors.initials: GR
authors.lastname: Blackburn
authors.forename: Harold
authors.initials: H
authors.lastname: Warren
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Lee
authors.forename: Michael P
authors.initials: MP
authors.lastname: Busch
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D001782:Blood Donors; D014355:Chagas Disease / Q000276:immunology* / Q000469:parasitology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods* / Q000592:standards; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D008403:Mass Screening / Q000379:methods*; D015531:Radioimmunoprecipitation Assay; D012680:Sensitivity and Specificity; D016036:Seroepidemiologic Studies; D013020:South America; D013781:Texas; D014349:Trypanosoma cruzi / Q000276:immunology*; D014481:United States
chemical_list: D000913:Antibodies, Protozoan