Rhinoviruses significantly affect day-to-day respiratory symptoms of children with asthma

© 2014 American Academy of Allergy, Asthma & Immunology. Background Viruses are frequently associated with acute exacerbations of asthma, but the extent to which they contribute to the level of day-to-day symptom control is less clear.Objective We sought to explore the relationship between viral infections, host and environmental factors, and respiratory symptoms in children.Methods Sixty-seven asthmatic children collected samples twice weekly for an average of 10 weeks. These included nasal wash fluid and exhaled breath for PCR-based detection of viral RNA, lung function measurements, and records of medication use and asthma and respiratory symptoms in the previous 3 days. Atopy, mite allergen exposure, and vitamin D levels were also measured. Mixed-model regression analyses were performed.Results Human rhinoviruses (hRVs) were detected in 25.5% of 1232 nasal samples and 11.5% of breath samples. Non-hRV viruses were detected in less than 3% of samples. hRV in nasal samples was associated with asthma symptoms (cough and phlegm: odds ratio = 2.0; 95% CI = 1.4-2.86, P =.0001; wheeze and chest tightness: odds ratio = 2.34, 95% CI = 1.55-3.52, P