Etiological agent of Roseola infantum includes
**Core Concept**
Roseola infantum, also known as sixth disease, is a viral exanthem that primarily affects infants and young children. The etiological agent responsible for this condition is a member of the herpesvirus family.
**Why the Correct Answer is Right**
The correct answer is a double-stranded DNA virus that belongs to the genus *Roseolovirus*. This virus is highly contagious and spreads through respiratory droplets, leading to a self-limiting illness characterized by a high fever followed by a distinctive rash. The virus infects B lymphocytes and causes a transient immunosuppression, which contributes to its pathogenesis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify a virus. Roseola infantum is a viral exanthem, not a bacterial or fungal infection.
**Option B:** This option is incorrect because the varicella-zoster virus is the etiological agent of chickenpox, not roseola infantum.
**Option C:** This option is incorrect because the coxsackievirus is a member of the enterovirus family and is associated with hand, foot, and mouth disease, not roseola infantum.
**Clinical Pearl / High-Yield Fact**
Roseola infantum typically affects children between 6 months and 2 years of age and is highly contagious during the prodromal phase, which is characterized by a high fever and the absence of a rash.
**Correct Answer: D. Human herpesvirus 6 (HHV-6) and Human herpesvirus 7 (HHV-7)**