AN 11-MONTH-OLD, previously healthy boy, was admitted after a 3-day history of daily fevers up to 38.8°C. The patient was otherwise active and playful and had no history of rhinorrhea, cough, vomiting, or diarrhea. On admission, his temperature was 38.8°C, but he was alert, well nourished, and in no respiratory distress. His chest was clear on auscultation, and the findings from the remainder of his examination showed no abnormalities. The white blood cell count was 20.7×109/L, with 0.61 segments, 0.06 band forms, and 0.29 lymphocytes, and 0.04 basophils. The hemoglobin level was 98 g/L (reference range, 140-175 g/L); hematocrit 0.28 (reference range, 0.41-0.50); and a platelet count of 0.001×109/L. A chest radiograph done on admission, with the patient in the right lateral decubitus position, is shown (Figure 1). Blood culture showed no growth of organisms after 72 hours, and purified protein derivative for tuberculin was nonreactive with a positive control.