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Causes
By Mayo Clinic staffBronchiolitis occurs when a virus infects the bronchioles, which are the smallest of the airways branching off the main breathing tubes (bronchi) within your lungs. The viral infection makes the bronchioles swell and become inflamed. Mucus collects in these airways, which can make it difficult for air to flow freely into and out from the lungs.
Most cases of bronchiolitis are caused by the respiratory syncytial virus (RSV). RSV is a common virus which infects just about every child by the age of 2. Seasonal outbreaks of RSV infection occur every winter. Bronchiolitis can also be caused by a variety of other viruses, including those that cause the flu or the common cold.
Bronchiolitis is a contagious condition. You contract the virus just as you would a cold or the flu — through droplets in the air when someone who is sick coughs, sneezes or talks. You can also contract bronchiolitis by touching shared objects — such as utensils, towels or toys — and then touching your eyes, nose or mouth.
- AskMayoExpert. Bronchiolitis. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2012.
- Piedra PA. Bronchiolitis in infants and children: Clinical features and diagnosis. http://www.uptodate.com/home/index.html. Accessed March 13, 2013
- Piedra PA. Bronchiolitis in infants and children: Treatment; outcome; and prevention. http://www.uptodate.com/home. Accessed March 13, 2013.
- Fitzgerald DA. Viral bronchiolitis for the clinician. Journal of Pediatrics and Child Health. 2011;47:160.
- American Academy of Pediatrics. Diagnosis and Management of Bronchiolitis. Pediatrics. 2006;118:1774.
- Pianosi PT. (Expert opinion.) Mayo Clinic, Rochester, Minn. April 5, 2013.
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