Bronchiolitis. Bronchiolitis occurs predominantly in the first year of life and with decreasing frequency in the second and third years. The clinical features are rapid breathing and lower chest wall indrawing, fever in one-third of cases, and wheezing (Cherian and others 1990). Inflammatory obstruction of the small airways, which leads to hyperinflation of the lungs, and collapse of segments of the lung occur. Because the signs and symptoms are also characteristic of pneumonia, health workers may find differentiating between bronchiolitis and pneumonia difficult. Two features that may help are a definition of the sea- sonality of RSVs in the locality and the skill to detect wheezing. RSVs are the main cause.
