Relapsing vivax malaria despite chemoprophylaxis in two blood donors who had travelled to Papua New Guinea.

Two Australian blood donors were diagnosed with relapsing Plasmodium vivax malaria 5 and 15 months, respectively, after their most recent travel to a malaria-endemic country. Common features included travel to Papua New Guinea (specifically, the Kokoda Trail); full compliance with recommended malaria chemoprophylaxis; and negative results on malaria antibody testing at the time of donation. Although all fresh blood components from the two donors issued on the basis of these negative results were recalled before transfusion, these cases underscore the increased potential for relapse of P. vivax in donors returning from malaria-endemic countries, as well as the inability to identify the potential for relapse using current malarial screening tests.