Vivax malaria.

Malaria occurs in the United States infrequently and is found exclusively among immigrants and travelers returning from areas where the disease is endemic. Cases of acute relapses of Plasmodium vivax infection can present to the emergency department. Patients are often immigrants from developing countries who were symptom-free in this country for weeks or months preceding their illness. The clinical presentation and current treatment of malaria are reviewed. Malarial infection may become apparent months after leaving endemic areas despite adherence to prophylactic regimens. The disease usually responds to appropriate drug therapy with rapid and often dramatic results, but it can be fatal if unrecognized.