A 10-month-old infant presents with a history of high fever (39 to 40 degrees C) for 4 days without any localizing signs. The child now becomes afebrile, and within 12 hours a pink maculopapular rash appears over the trunk and spreads to the face and extremities. The child appears well and playful. Which virus is the most likely cause?
- A Human herpesvirus 6 ✓
- B Parvovirus B19
- C Rubella virus
- D Coxsackievirus A16
Correct answer: A. Human herpesvirus 6
Explanation
Exanthem subitum (roseola infantum) is caused by human herpesvirus 6, typically between 6 months and 2 years. The hallmark is 3 to 5 days of continuous high fever that abruptly resolves, followed by appearance of the rash as defervescence occurs, and the child remains well. This 'rash appears when fever falls' pattern distinguishes it from measles, where the rash appears while fever persists and Koplik spots are present.
Reference: Nelson Textbook of Pediatrics, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.