HISTORY
A 14-month-old girl presented with persistent fever, cough, and worsening rash of 5 days’ duration. On the first day of the illness, the infant was brought to an acute care clinic for evaluation. Upper respiratory tract infection was diagnosed; her parents were instructed to use nasal saline and provide acetaminophen, as needed. Two days before presentation, she was brought to an outpatient clinic, where secondary otitis media on the left side was diagnosed and treatment with amoxicillin(Drug information on amoxicillin), 40 mg/kg/d in 2 doses for 10 days, was prescribed. On the day of presentation, the parents reported that the rash, which began on the cheeks and chest, had spread to other areas and the cough and fever had persisted.
PHYSICAL EXAMINATION
Temperature was 37.6ºC (99.7ºF); respiration rate, 33 breaths per minute, without retractions or signs of distress. Maculopapular rash on the forehead, cheeks, neck, chest, back, and arms, with fewer macules on the upper thighs and sparing of the lower limbs. Gingival mucosa showed some hyperemia of the posterior palate, no enanthem; tonsils red and inflamed, with no white plaques. Infant had been taking solids and liquids without problem. Heart, abdominal, and genital findings normal.
INITIAL LABORATORY RESULTS
White blood cell count of 15,900/µL, with 4% bands, 12% neutrophils, 67% lymphocytes, 9% atypical lymphocytes, and 6% eosinophils; hemoglobin, 11.3 g/dL; and hematocrit 32.4%, with normal red cell indices. Bicarbonate level, 17 mEq/L (normal, 21 to 33 mEq/L), with anion gap of 20 mEq/L; liver enzyme levels normal; and alkaline phosphatase level, 1736 U/L (normal, 108 to 317 U/L).
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