Infections

Wheezing with respiratory infections is extremely common in early childhood. It is estimated that the prevalence of wheezing during the first five years of life varies from 30–60%. In the majority of children who experience wheezing with respiratory infections, these episodes of wheezing become less frequent as the child grows older. However, determining whether the initial episode of wheezing with a viral respiratory illness is an important factor in the eventual development of asthma is an important question. Although a significant body of information suggests an association between respiratory tract illnesses in early life and the later development of airway dysfunction, this relationship is difficult to establish and indicates the complexity of factors that surround the development of bronchial hyperresponsiveness and eventual expression of asthma. A similarly important issue to resolve is the relationship between respiratory infections and the pathogenesis of airway hyperresponsiveness. It is apparent that viral, not bacterial, upper respiratory infections (URIs) trigger asthma attacks. With the use of more sensitive techniques to identify respiratory viruses, the relationship between respiratory infections, particularly viral URIs, and asthma has become even more convincing and important.