An acute viral syndrome of the bronchioles characterized by wheezing and respiratory distress. Airway resistence in the smaller air passages increases during both inspiration and expiration but since the radius of the airway is smaller during expiration, the resulting ball-valve respiratory obstruction leads to early air trapping and overinflation.
Atelectasis occurs when the obstruction becomes complete and trapped air is absorbed.
RSV is shed from the respiratory tract for an average of 9 days in children under 1 year of age and for up to months in infants with immunodeficiency syndromes. Clinical age, season, clinical features 2. Imaging Studies 1.