Canadian Blood Services traceback investigation of a suspected case of transfusion-transmitted malaria.

This was a probable transfusion-transmitted malaria (TTM) case from an eligible donor who in retrospect was found to have unrecognized, asymptomatic, semi-immune malaria infection, and who was potentially infectious. Blood donor lack of recall of prior malaria infection does not negate the risk of TTM from those who have lived in malaria-endemic countries.