Visual Diagnosis: An Infant Who Has Fever and Rash

Presentation

A 9-month-old girl is brought to the clinic because of worsening fever and rash. Three days ago, she developed a fever of 38.8°C (101.8°F) and pinpoint flesh-colored “bumps” on the abdomen. The rash soon turned red and quickly spread to the entire body, but it was not pruritic. The following day she developed clear rhinorrhea and a cough severe enough to cause posttussive emesis. The fever persisted for the next 2 days despite administration of ibuprofen. The increasing irritability and fever of 40.0°C (104°F) prompted her mother to bring her to the clinic. The child’s appetite is poor, but she does drink, and her urine output has not diminished. There is no diarrhea. Her mother denies administering any medication other than ibuprofen. The child has been healthy previously, and her mother is unaware of any known illness contacts. She has received her primary immunization series for diphtheria, tetanus, pertussis, polio, Haemophilus influenzae type b, and hepatitis B. Of note, she and her family traveled cross-country by automobile 2 weeks ago.

Physical examination reveals an irritable but consolable infant who has a red rash consisting of raised spots and flat, confluent patches (Fig. 1⇓). She has a temperature of 38.3°C (101.8°F), respiratory rate of 42 breaths/min, and pulse of 152 beats/min. Discrete, intensely red, raised …