Trypanosoma cruzi infection in North America and Spain: evidence in support of transfusion transmission.

BACKGROUND: The United States, Canada, and Spain perform selective testing of blood donors for Trypanosoma cruzi infection (Chagas disease) to prevent transfusion transmission. The donor, product, and patient characteristics associated with transfusion-transmitted infections are reviewed and the infectivity of components from donors with serologic evidence of infection is estimated. STUDY DESIGN AND METHODS: A systematic review of transfusion-transmitted T. cruzi cases and recipient tracing undertaken in North America and Spain is described. Cases were assessed for the imputability of the evidence for transfusion transmission.
RESULTS: T. cruzi infection in 20 transfusion recipients was linked to 18 serologically confirmed donors between 1987 and 2011, including 11 identified only by recipient tracing. Cases were geographically widely distributed and were not associated with incident or autochthonous infections. Index clinical cases were described only in immunocompromised patients. All definite transmissions (n = 11) implicated apheresis or whole blood-derived platelets (PLTs), including leukoreduced and irradiated products. There is no evidence of transmission by red blood cells (RBCs) or frozen products, while transmission by whole blood transfusion remains a possibility. Recipient tracing reveals low component infectivity from serologically confirmed, infected donors of 1.7% (95% confidence interval [CI], 0.7%-3.5%) overall: 13.3% (95% CI, 5.6%-25.7%) for PLTs, 0.0% (95% CI, 0.0%-1.5%) for RBCs, and 0.0% (95% CI, 0%-3.7%) for plasma and cryoprecipitate.
CONCLUSIONS: T. cruzi is transmitted by PLT components from some donors with serologic evidence of infection. Evidence of transmission before the implementation of widespread testing in the countries studied is sparse, and selective testing of only PLT and fresh whole blood donations should be considered.