Plasmodium malariae after successful treatment of P. falciparum malaria with artemether-lumefantrine

We described a case of Plasmodium malariae malaria in a traveler returning from the Democratic Republic of Congo to Belgium. This occurred despite successful artemether-lumefantrine treatment for Plasmodium falciparum three weeks earlier and in the absence of re-exposure in an endemic area. We discuss possible explanations for this unusual observation.