Viral rhinitis and asthma.

Upper respiratory tract infections are among the most common infectious diseases. Approximately 80% of the common colds are caused by rhinoviruses. Recently, rhinovirus colds have been linked with lower airway illnesses such as asthma exacerbations resulting in a considerable interest in the pathogenesis of lower respiratory tract pathology. The important role that allergic airway disease plays in virally induced changes in airway function has been experimentally shown in several studies. Unfortunately, the precise mechanisms by which viruses could induce lower airway symptoms have not yet been determined.