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Bronchiolitis is swelling and mucus buildup in the smallest air passages in the lungs (bronchioles), usually due to a viral infection.
Bronchiolitis usually affects children under the age of 2, with a peak age of 3 - 6 months. It is a common, and sometimes severe illness. Respiratory syncytial virus (RSV) is the most common cause. More than half of all infants are exposed to this virus by their first birthday.
Other viruses that can cause bronchiolitis include:
You can catch the virus if you come into direct contact with nasal fluids or airborne droplets from someone who has the illness. This may happen if the person sneezes or coughs near you.
Bronchiolitis is seasonal and appears more often in the fall and winter months. It is a very common reason for infants to be hospitalized during winter and early spring.
Risk factors for bronchiolitis include:
Watts KD, Goodman DM. Wheezing, bronchiolitis, and bronchitis. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 383.
American Academy of Pediatrics Subcommittee on the Diagnosis and Management of Bronchiolitis. Diagnosis and management of bronchiolitis. Pediatrics. 2006;118:1774-1793.
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