Roseola infantum can be caused by –
**Core Concept**
Roseola infantum, also known as exanthem subitum, is a viral exanthem that primarily affects infants and young children. It is characterized by a sudden onset of high fever, followed by a distinctive maculopapular rash.
**Why the Correct Answer is Right**
Roseola infantum is primarily caused by human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7). These viruses are highly contagious and are typically acquired through close contact with an infected individual. The infection leads to a sudden onset of high fever, which can last for 3-5 days, followed by the appearance of a rash. The rash usually appears after the fever has resolved and is characterized by small, pink, flat spots that may coalesce to form larger patches.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as measles virus primarily causes measles, a different viral exanthem characterized by a distinctive cough, conjunctivitis, and a more widespread rash.
**Option B:** This option is incorrect as rubella virus primarily causes German measles, a viral exanthem characterized by a rash, fever, and lymphadenopathy, but it does not typically cause roseola infantum.
**Option C:** This option is incorrect as varicella-zoster virus primarily causes chickenpox, a viral exanthem characterized by a rash of vesicles that crust over and leave scars.
**Clinical Pearl / High-Yield Fact**
Roseola infantum is a common cause of febrile seizures in infants and young children, and it is essential to recognize the characteristic rash and history of high fever to diagnose this condition.
**Correct Answer:** D. Human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7)