Which virus most commonly causes bronchiolitis?

Which virus most commonly causes bronchiolitis?

• A. Parainfluenza
• B. Adenovirus
• C. Influenza
• D. RSV

Answer: (D)

Bronchiolitis in young children is most commonly caused by respiratory syncytial virus (RSV). RSV has a particular tendency to infect the small airways (bronchioles), leading to inflammation, edema, and increased mucus production that narrows these tiny passages. This pathophysiology produces the wheezing, rapid breathing, and sometimes chest retractions that define bronchiolitis. Because this virus is the leading cause in children under about two years old, especially during winter months, RSV stands out as the principal etiologic agent. Other viruses like parainfluenza, adenovirus, and influenza can cause bronchiolitis or similar lower respiratory illnesses, but they are less commonly responsible for the classic bronchiolitis seen in infants, and parainfluenza is more often linked to croup.

Bronchiolitis in young children is most commonly caused by respiratory syncytial virus (RSV). RSV has a particular tendency to infect the small airways (bronchioles), leading to inflammation, edema, and increased mucus production that narrows these tiny passages. This pathophysiology produces the wheezing, rapid breathing, and sometimes chest retractions that define bronchiolitis. Because this virus is the leading cause in children under about two years old, especially during winter months, RSV stands out as the principal etiologic agent.

Other viruses like parainfluenza, adenovirus, and influenza can cause bronchiolitis or similar lower respiratory illnesses, but they are less commonly responsible for the classic bronchiolitis seen in infants, and parainfluenza is more often linked to croup.