Background: Because Trypanosoma cruzi (T. cruzi) infection in Canada and the United States is largely contracted in endemic countries, targeted testing of blood donors with risk travel may improve safety. The operational validity of a travel question suitable for donor screening was tested, and it was field-tested.
Study design and methods: After 1331 donors completed a short travel question, operational validity was assessed by detailed travel histories in face-to-face interviews. Two nationwide donor surveys were carried out assessing donor responses to similar travel questions in 2001 (13,623 donors) and in 2006 (20,037 donors). All donors in Toronto, Ontario, answered a travel question in 1997 and those born in or who spent 6 months or more in Mexico, Central America, or South America were tested for antibody to T. cruzi.
Results: There was 97.3 percent agreement between the travel question and detailed interviews, with 15 donors (1.1%) failing to acknowledge risk travel (false-negative questioning responses). Of these, 6 donors were born there and 7 others had less than 1 year of cumulative travel. In 2001 and 2006, there were 2.1 and 2.0 percent of donors with risk travel, respectively, but 16.5 and 11.2 percent of these donors were identified only because they were born there (travel not acknowledge). There were 1337 (1.6%) donors in Toronto in 1997 with risk travel and none were positive for the presence of T. cruzi antibody.
Conclusion: Donors can answer a short question about cumulative time in Latin America with similar accuracy to detailed questioning, but screening questions should also include country of birth.