Donors deferred for self-reported Chagas disease history: does it reduce risk?




Current Food and Drug Administration guidance specifies that all blood donors must be asked about a history of Chagas disease.

Study Design and Methods

We identified all American Red Cross donors deferred for Chagas disease history from January 2000 to August 2011. Attempts were made to contact all deferred donors and invite them back for anti-Trypanosoma cruzi testing. After January 2007, all accepted donors (no Chagas history) were anti-T. cruzi tested.


Over the 12-year period (approx. 88 million donor presentations), 34 donors had a Chagas deferral. When contacted, seven reported risk (e.g., travel or residence in an endemic area, vector exposure) and six were anti-T. cruzi tested with one radioimmunoprecipitation assay (RIPA) positive. Six others had answered the question incorrectly. The remaining 21 could not be contacted but from the donor record it could be determined that 13 were Hispanic ethnicity or Spanish speaking and/or provided specific details of Chagas risk or disease.


In 12 years, only 28 potentially infected donors were identified using the Chagas question. Limited testing data suggest that few of these would have had serologic evidence of prior infection. In contrast, nearly 5 years of anti-T. cruzi screening identified 488 RIPA-positive donors, none of whom answered “yes” to the Chagas question. According to estimates in this study, the value of retaining the questionnaire in addition to testing translates to preventing the collection of 0.4 infected donors per billion. Thus, the Chagas history question has no meaningful value.