Organism in bronchiolitis is:
**Core Concept**
Bronchiolitis is a common lower respiratory tract infection that primarily affects infants and young children, caused by various viral pathogens. The most common cause of bronchiolitis is the **Respiratory Syncytial Virus (RSV)**.
**Why the Correct Answer is Right**
The correct answer is related to the **Respiratory Syncytial Virus (RSV)**, which is the most frequent cause of bronchiolitis in infants and young children. RSV infects the epithelial cells lining the small airways, leading to inflammation, increased mucus production, and airway obstruction.
**Why Each Wrong Option is Incorrect**
**Option A:** Influenza virus, while a respiratory pathogen, is not the primary cause of bronchiolitis.
**Option B:** Adenovirus can cause respiratory infections but is less commonly associated with bronchiolitis than RSV.
**Option D:** Other viruses and bacteria can cause respiratory infections, but they are not the primary cause of bronchiolitis.
**Clinical Pearl / High-Yield Fact**
RSV is highly contagious and spreads through close contact with infected individuals or contaminated surfaces.
**Correct Answer:** D. Respiratory Syncytial Virus.