Lower airway responses to influenza A virus in healthy allergic and nonallergic subjects.

Acute asthma is considered a complication of respiratory viral infections. This investigation assessed the effects of influenza A virus infection on both the patency and responsiveness of the lower airways. Subjects with allergic rhinitis (AR; n = 21) and without AR (non-AR; n = 25) were intranasally inoculated with influenza A virus and monitored for 8 d in a cloistered environment for changes in symptoms, signs, and airway physiology (pulmonary function, bronchial methacholine provocation). All subjects were infected after inoculation. Significant increases in nasal symptoms and secretion weights were observed, with peak effects on Days 3 and 4. Cough was a relatively minor symptom, and none of the subjects developed wheezing. Likewise, there were no significant changes in the measured functions of the lower airways. No effects on allergy status were observed. Under these experimental conditions, influenza A virus infection did not produce detectable alterations in lower airway function in health AR and non-AR subjects.