What symptom is characteristic of roseola infantum?

Roseola infantum, commonly caused by human herpesvirus 6 (HHV-6), is characterized predominantly by a sudden high fever that lasts for three to five days, followed by the appearance of a distinctive rash. The pattern of a high fever preceding the rash is a hallmark of this condition, making it easy for clinicians to identify. After the fever subsides, a rose-colored rash typically erupts, starting on the torso and then spreading to other areas of the body.

The nature of the fever and subsequent rash is important for diagnosis; understanding this helps to differentiate roseola from other febrile illnesses in infants and young children. For example, other viral rashes may not exhibit the same clear pattern of fever prior to the rash or might be accompanied by symptoms not typical of roseola, such as cough or sore throat. Recognizing this classic presentation is crucial for effective management and reassurance to parents, as the illness is usually benign and self-limiting.