The role of respiratory infections in airway hyperresponsiveness and asthma.
Viruses provoke symptoms of wheezing in many patients with asthma. Furthermore, there is evidence that viruses increase airway responsiveness in non-asthma patients. The mechanisms involved in these reactions are not clearly established, but evidence suggests that the ability of viruses to promote this bronchial responsiveness may be related to an upregulation of the allergic inflammatory reaction. This would explain why patients may be more prone to have a late asthmatic reaction.