Evaluation of a new Trypanosoma cruzi antibody assay for blood donor screening.
BACKGROUND
This multicenter prospective study was designed to evaluate the performance characteristics of a new commercially available enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to Trypanosoma cruzi in blood donors, the ORTHO T. cruzi ELISA Test System (Ortho-Clinical Diagnostics).


METHODS
Assay specificity was evaluated among 40,665 serum and ethylenediaminetetraacetate (EDTA) plasma specimens from volunteer blood donors and 481 T. cruzi antibody-negative specimens from a high-risk population. Sensitivity was evaluated among 106 T. cruzi-infected subjects identified by parasite detection, among 93 radioimmunoprecipitation assay (RIPA)-positive specimens from high-risk subjects, and 662 specimens presumed positive for the presence of T. cruzi antibodies by serologic methods. Also assessed were the equivalence of serum and plasma as specimen sources, performance equivalence of automated and semiautomated processing methods, nonspecific reactivity in specimens from other disease states or clinical conditions, and assay precision.


RESULTS
Assay specificity was 99.998 percent in volunteer blood donors and 99.4 percent among high-risk subjects. Sensitivity was 100 percent among specimens positive by parasite detection, or by serologic methods, and 98.9 percent among RIPA-positive specimens from high-risk subjects. No differences were demonstrated between serum and plasma or between semiautomated and automated processing methods. Cross-reactivity was observed with known positive leishmaniasis specimens. Total inter- and intraassay variability was less than 10 percent with both the automated and the semiautomated methods.


CONCLUSIONS
The ORTHO T. cruzi ELISA Test System is an effective, qualitative assay for screening blood donors for immunoglobulin G antibodies to T. cruzi. The assay was licensed for donor screening by the FDA in December 2006.
Gorlin
Jed
J
Memorial Blood Centers, St Paul, Minnesota 55114, USA. jed@mbc.org
Rossmann
Susan
S
Robertson
Gene
G
Stallone
Fred
F
Hirschler
Nora
N
Nguyen
Kim-Anh
KA
Gilcher
Ronald
R
Fernandes
Helen
H
Alvey
Stacey
S
Ajongwen
Patience
P
Contestable
Paul
P
Warren
Harold
H
D000465:Algorithms; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D001782:Blood Donors; D014355:Chagas Disease / Q000097:blood / Q000175:diagnosis / Q000469:parasitology; D046148:Donor Selection / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D011446:Prospective Studies; D015531:Radioimmunoprecipitation Assay / Q000379:methods; D015203:Reproducibility of Results; D014349:Trypanosoma cruzi / Q000276:immunology*
D000913:Antibodies, Protozoan