A 15-month-old child develops a high fever that resolves, followed by a maculopapular rash. What condition does this describe?

The scenario described, where a 15-month-old child experiences a high fever that subsequently resolves followed by the appearance of a maculopapular rash, is characteristic of roseola infantum. This viral infection is commonly seen in young children and is caused by human herpesvirus 6 (HHV-6), although other strains like HHV-7 can also be implicated.

In roseola, the illness typically begins with a sudden high fever that can persist for several days. Once the fever resolves, a distinctive rash develops, usually beginning on the trunk and then spreading to the extremities. The rash is often macular and may be slightly raised, but it is typically not itchy. This progression of symptoms—first a high fever and then the rash—is key in identifying roseola infantum.

Other conditions listed, such as erythema infectiosum (commonly known as fifth disease), primarily presents with a "slapped cheek" appearance in older children and may not follow the exact pattern of high fever preceding the rash. Scarlet fever can present with a rash but is often accompanied by other symptoms, such as a sore throat and "strawberry tongue," not typically related to the fever followed by rash progression seen in roseola