Bronchiolitis is best described as which of the following?

• A. A viral infection of the lower airway that commonly affects infants and children younger than 2 years of age
• B. A bacterial infection of the upper airway
• C. A fungal infection of the lungs
• D. An allergic inflammatory reaction of the airways

Answer: (A)

Bronchiolitis is a viral infection of the lower airways that commonly affects infants and children younger than two years. It is most often caused by RSV and involves inflammation of the bronchioles, leading to airway obstruction with wheeze, tachypnea, and increased work of breathing, sometimes with fever and nasal symptoms. This description fits because bronchiolitis is a small-airway (lower respiratory tract) viral illness in very young children, rather than a bacterial infection of the upper airway, a fungal lung infection, or an allergic inflammatory process. Management is typically supportive, focusing on hydration, nasal suctioning, and oxygen if needed, with antibiotics not routinely indicated unless a bacterial coinfection is suspected.