Outcomes in Military Blood Donors at Joint Base San Antonio With Reactive Trypanosoma cruzi Antibody Screening Results.

Background: All blood donors in the United States are universally screened once for Trypanosoma cruzi antibodies to prevent transfusion-transmitted Chagas disease, but military donors are screened with every donation. Previous studies of military blood donors demonstrated that reactive T cruzi antibodies were a common reason for postdonation deferral, but follow-up is unclear. This study evaluated the diagnostic evaluation of blood donors with reactive T cruzi screening results.

Methods: Medical records of all blood donors at the Armed Services Blood Bank Center at Joint Base San Antonio-Lackland with reactive screening results for T cruzi antibodies between January 2017 to December 2022 were evaluated after chemiluminescent immunoassay or chemiluminescent microparticle immunoassay screening and enzyme strip assay supplementary testing. Records were assessed to determine the diagnostic evaluation and final diagnosis of each case following initial reactive screening results.

Results: Of 89,459 blood donors during the study period, 49 (0.055%) screened reactive for T cruzi antibodies on initial blood donation. Of those, 4 (8%) had positive and 18 (36%) had indeterminate supplementary test results. No donors met criteria for Chagas disease on clinical diagnostic testing. Of the 8 with repeated screening testing ordered in the weeks after their original reactive result, only 1 (13%) had a repeated reactive screening test result but negative confirmatory serologic results.

Conclusions: While reactive T cruzi screening results occurred in this cohort, there were no cases of Chagas disease. This study demonstrates that some military blood donors have transient reactivity with screening assays, and future work should determine ways to safely bring these donors without Chagas disease back into the donor pool.