Plasmodium vivax malaria in spite of atovaquone/proguanil (malarone) prophylaxis

A 70-year-old male scientist, who had returned 5 weeks earlier from Ethiopia, was admitted to the hospital with symptoms consistent with malaria. On physical examination, he had orthostatic hypotension. He was dehydrated and showed a mild clinical delirium. Abdominal examination revealed a possible spleen tip, and he had petechial lesions bilaterally below his knees. Laboratory data revealed his white blood cell count to be 4,500/mL, with 67% polymorphonuclear cells and 15% band forms. The hemoglobin level was 13.9 g/dL, and the platelet count was low, at 32,000/mL.