Roseola infantum is caused by which virus?

Roseola infantum, also known simply as roseola, is primarily caused by human herpesvirus 6 (HHV-6). This viral infection commonly affects children and is characterized by a sudden high fever followed by the appearance of a distinctive rash once the fever subsides.

HHV-6 is known to have two distinct forms, HHV-6A and HHV-6B. HHV-6B is the strain most commonly associated with roseola. The infection is typically mild and self-limiting, often resolving with supportive care.

Understanding the mechanism of transmission and symptoms associated with roseola is crucial for pediatric care, as differentiation from other febrile illnesses is important for management and reassurance to parents. The other viruses listed in the choices—HHV-7, cytomegalovirus (CMV), and varicella-zoster virus—are not the primary causative agents of roseola, which emphasizes the importance of accurately identifying HHV-6 in clinical presentations of this illness.