Herpes zoster oticus is caused by-
**Core Concept**
Herpes zoster oticus, also known as Ramsay Hunt syndrome type 2, is a viral infection affecting the geniculate ganglion of the facial nerve, leading to a characteristic rash and symptoms of facial paralysis.
**Why the Correct Answer is Right**
The correct answer is **Varicella-zoster virus (VZV)**, which is the same virus responsible for chickenpox and shingles. Reactivation of latent VZV in the geniculate ganglion causes the characteristic symptoms of herpes zoster oticus. This reactivation is thought to occur due to immune system decline or stress, leading to the virus's reactivation from its latent state in the dorsal root ganglia or geniculate ganglion.
**Why Each Wrong Option is Incorrect**
* **Option A:** Herpes simplex virus is not associated with herpes zoster oticus, which is a distinct clinical entity caused by VZV.
* **Option B:** Human herpesvirus 6 (HHV-6) is a different type of herpesvirus, not related to herpes zoster oticus.
* **Option C:** Cytomegalovirus (CMV) is another type of herpesvirus, but it is not associated with herpes zoster oticus.
**Clinical Pearl / High-Yield Fact**
Herpes zoster oticus is a clinical emergency, as it can lead to significant complications, including facial paralysis, hearing loss, and otitis media. Prompt treatment with antiviral medications, such as acyclovir, can help reduce the severity and duration of symptoms.
**Correct Answer:** D. Varicella-zoster virus (VZV)