RSV is the major cause of lower respiratory tract infections in young children. It is a paramyxovirus that is found in ocular or nasal secretions and on fomites. It is also a nosocomial pathogen, so it is crucial to take precautions and prevent the spread of disease. The incubation period varies from 2 to 8 days. RSV may localize to the upper airway, but 50% or more of infections in infants spread to the lower respiratory tract. Therefore, bronchiolitis and pneumonia are often a result of RSV infection.

In bronchiolitis, viruses induce necrosis of bronchiolar epithelium, increased mucus secretion, and edema of the submucosa. Mucus obstructs the bronchioles and this leads to hyperinflation and collapse of lung tissue. Patients initially experience fever, rhinorrhea, pharyngitis, and cough; after the initial few days, they can develop tachypnea and wheezing. Each year, as many as 90,000 infants are hospitalized in the United States for bronchio- litis.

The treatment for RSV is largely supportive care. Children often require close observation, intravenous fluids, and supplemental oxygen. Bronchodilators and steroids are often used, but have limited efficacy. Steroids are postulated to have an impact on bronchiolitis by decreasing bronchiolar inflammation and hyperactivity. However, treatment with intravenous steroids has not demonstrated clinical improvements. The American Academy of Pediatrics’ 2006 clinical practice guidelines, Diagnosis and Management of Bronchiolitis, does not recommend corticosteroids or bronchodilators in the management of bronchiolitis.