Recurrent Plasmodium falciparum Malaria in U.S. Travelers Treated with Artemether–Lumefantrine

We report two cases of recurrent malaria in U.S. travelers returning from Africa (Ghana and Central African Republic) despite a full course of artemether–lumefantrine (AL). Both patients presented to New York City hospitals, received AL treatment, and clinically improved. Within 2 weeks, they presented with recurrent Plasmodium falciparum malaria. Parasite isolates were sequenced, and P. falciparum kelch 13 propeller domain mutations that are validated or candidate markers of artemisinin partial resistance were not identified. Parasites had mutations within the P. falciparum multidrug resistance protein 1 gene. It is crucial to remain vigilant for recurrent malaria in travelers, even from African regions where partial resistance to artemisinin-based combination therapy has only rarely been reported.