Diagnostic evaluation of military blood donors screening positive for Trypanosoma cruzi infection.

Routine blood donor screening for Trypanosoma cruzi, the causative parasitic agent of Chagas disease, began in the U.S. in 2007. Results of follow-up testing and evaluation after a positive screen have not been studied in the armed forces. Among first-time donors at the Joint Base San Antonio- Lackland Blood Donor Center between January 2014 and December 2016 (N=43,402), a total of 23 (0.05%) screened positive for T. cruzi. This descriptive study highlights demographic and follow-up information for all 22 active duty service members who screened positive; a non-active duty member was excluded due to unavailability of clinical records. Members who screened positive received 13 different combinations of confirmatory testing (mean: 2.7 tests per person). In select cases, clinical evaluation included electrocardiogram (n=15) and 30-second rhythm strip (n=5). Two patients met criteria for Chagas disease; 11 patients were considered negative; and nine patients were indeterminate. Among a small cohort of active duty service members who screened positive for T. cruzi infection on blood donation, diagnostic evaluation varied considerably. Opportunities exist to decrease heterogeneity of clinical workup and improve evaluation of persons who screen positive.