Comparison between chimeric Trypanosoma cruzi antigens (ABBOTT PRISM Chagas assay) and local antigenic extracts in blood bank screening for Chagas disease in an endemic area for the Triatoma dimidiata vector

Trypanosoma cruzi can be transmitted by blood transfusion in non-endemic areas, and in endemic areas the risks may be higher. We investigated the seroprevalence of anti-T. cruzi antibodies in 1,500 blood donors from a blood bank in an endemic area where Triatoma dimidiata constitutes the main vector and in 2,800 healthy young subjects. Choosing antigens is crucial in diagnostic tests as it directly influences performance across regions. We screened 1,500 blood donors in parallel for chimeric Trypanosoma cruzi antigens with the ABBOTT PRISM Chagas assay at the State Blood Transfusion Center and with an in-house ELISA assay using local T. cruzi antigenic extracts at a Biomedical Research Center laboratory. Overall, 13 T. cruzi isolates from the Yucatan Peninsula, Mexico, were characterized for their antigenic profiles before being used in an in-house ELISAs. All T. cruzi isolates shared immunodominant antigens among themselves and with South American strains (particularly those below 100 kDa). Seroprevalence of anti-T. cruzi antibodies in blood donors totaled 0.2% (3/1500) in the ABBOTT PRISM Chagas assay and 0.26% (4/1500) in the in-house ELISA. We found low sensitivity (33%; 95%CI 0.01710 to 0.8815), high specificity (99.8%; 95%CI 0.9941 to 0.9995), and a low kappa index (0.2). Seroprevalence in young subjects totaled 0.14 %. We found comparable seroprevalence to blood banks in large Mexican municipalities free of vector transmission. Thus, optimal public immunodominant antigens are needed to cover the broad immune spectrum induced by T. cruzi infection.