This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Impoant Viral Diseases in Children, Subject name: Pediatrics
A child presents with history of high fever for 4 days along with seizures. A rash develops on trunk on the day after the fever subsides. What is the most probable diagnosis? 
Select and explain. 
A. Roseola infantum, B. Measles, C. Rubella, D. Varicella
A: Roseola infantum
Answer: A: Roseola infantum 
Explanation: History of high fever & rash appearing as the fever subsides is suggestive of Roseola infantum. -Roseola infantum/sixth disease/exanthema subitum * Caused by herpes virus (HHV6A and 6B) * Clinical features: Sudden onset of high fever Rash appear when the fever subsides Nagayama spots are seen * Lab findings in Roseola infantum Relative Lymphocytosis Leukopenia