A 3½-year-old boy, who lives in the southeastern United States, is referred for evaluation of eosinophilia that was detected on laboratory tests performed during a routine health supervision visit. A few days ago, he had loose stools, without blood or mucus, associated with low-grade fever. He has no history of significant illness, allergies, respiratory symptoms, weight loss, sick contacts, or travel. He is not taking any medications. He lives with his mother, aunt, three siblings, four cousins, and two dogs in a rural area that has city water and sewage. He frequently plays outside the house.

Physical findings, including vital signs, are within normal limits except for some scratch marks on his trunk and extremities. His WBC count is 35×103/mcL (35×109/L) with 56% eosinophils (absolute eosinophil count [AEC] of 19.8×103/mcL [19.8×109/L]). The rest of the laboratory evaluation, including a metabolic panel and...

You do not currently have access to this content.