Abstract
A 4-year-old boy from the United States had been staying in Indonesia for five months when he presented with fever, severe lethargy, progressive weight loss, and abdominal distension. He was first diagnosed with Plasmodium vivax infection in Indonesia and received treatment with chloroquine. However, his condition continued to deteriorate and he required erythrocyte transfusion for severe anemia. Three weeks into his illness, he was found to have low parasitemia with Plasmodium falciparum with massive hepatosplenomegaly in Singapore. A splenic infarct was also documented on computed tomography. Treatment with atovaquone-proguanil resulted in stabilization of the hemoglobin level and rapid reduction in splenic size, with clearance of malarial parasites from the bloodstream. Although reported typically in adult tropical residents, hyper-reactive malarial splenomegaly may occasionally be found in the pediatric traveler. Clinicians receiving children returning from the tropical regions should be aware of this potentially life-threatening complication of partially treated malaria.