**Question:** Most common viral disease affecting parotid glands -

A. Herpes Simplex Virus (HSV)
B. Human Herpesvirus 1 (HHV-1)
C. Parotid Gland Tumour
D. Infectious Mononucleosis (Mono)

**Core Concept:**
Parotid glands are the largest salivary glands located in the face, one on each side of the face, above and in front of the ears. They play a crucial role in saliva production and are primarily affected in certain viral infections. The question is asking about the most common viral disease involving parotid glands. In this context, we should focus on viral infections causing inflammation and swelling of the salivary glands.

**Why the Correct Answer is Right:**
The correct answer is Infectious Mononucleosis (Mono), also known as glandular fever, caused by the Epstein-Barr virus (EBV). EBV belongs to the family of herpesviruses and is highly contagious. Mono is a common infection in childhood and adolescence, often transmitted through saliva. It is characterized by fever, fatigue, and lymphadenopathy (swelling of lymph nodes) along with salivary gland inflammation (sialadenitis) and swelling in the parotid glands, leading to the clinical entity known as "Moon Face."

**Why Each Wrong Option is Incorrect:**

A. Herpes Simplex Virus (HSV) typically causes herpes labialis (cold sores) around the mouth and lips, not primarily affecting parotid glands. HSV is not the most common cause of parotid gland inflammation.

B. Human Herpesvirus 1 (HHV-1) is responsible for oral herpes (cold sores) around the mouth, not affecting parotid glands.

C. Parotid Gland Tumour refers to a benign or malignant growth in the parotid gland, not a viral disease. This option is incorrect as it discusses a condition resulting from a mass or growth rather than a viral infection affecting the parotid glands.

**Clinical Pearls:**

1. Infectious Mononucleosis (Mono) is a common viral infection in childhood and adolescence, often transmitted through saliva. It is a classic example of a viral infection causing lymphadenopathy, fever, and salivary gland inflammation.
2. The Epstein-Barr virus (EBV) is responsible for the clinical entity of Infectious Mononucleosis (Mono).
3. Herpesviruses (HSV, HHV-1) are primarily associated with oral herpes and do not cause parotid gland inflammation as commonly seen in Mono.
4. Parotid Gland Tumour refers to a benign or malignant growth in the parotid gland, not a viral disease affecting the glands.

**Core Concept:**

EBV belongs to the herpesviridae family and is known for causing infectious mononucleosis (Mono). Infectious Mononucleosis presents with symptoms like fever, lymphadenopathy, and salivary gland inflammation. Parot