VIRUS-INDUCED WHEEZING IN CHILDREN: Respiratory Syncytial Virus (RSV) and Rhinovirus

The strong association between infantile wheezing and respiratory tract infections caused by the respiratory syncytial virus (RSV) has been well established. In studies of older children, rhinovirus becomes the major virus associated with asthma. These relationships are outlined in the box on page 36. In the past, this relationship was more difficult to appreciate, because rhinovirus does not always grow well in culture. In addition, the linkage between asthma and atopy during childhood has raised the question whether viral infections alone can precipitate exacerbations of asthma. Use of the polymerase chain reaction (PCR) to measure viral nucleic acid material has provided the opportunity to study virus-induced wheezing among children in greater detail, and investigations of experimental rhinovirus infections in adults have demonstrated how this virus can augment both the early and late phase manifestations of airway hyperreactivity. This article reviews recent advances that have enhanced our understanding of virus-induced wheezing, along with new information indicating that interactions between viral infections and allergic inflammation may be critical to the pathogenesis of acute symptoms.