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

Abstract

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 < .0001) and with cold symptoms, as reported concurrently with sampling and 3 to 4 days later. No differences were found between the 3 hRV genotypes (hRV-A, hRV-B, and hRV-C) in symptom risk. A history of inhaled corticosteroid use, but not atopic status, mite allergen exposure, or vitamin D levels, modified the association between viruses and asthma symptoms.

Conclusion: The detection of nasal hRV was associated with a significantly increased risk of day-to-day asthma symptoms in children. Host, virus genotype, and environmental factors each had only a small or no effect on the relationship of viral infections to asthma symptoms.

Keywords: Virus; asthma; asthma control; children; mixed-model analysis; respiratory; rhinovirus.

Fig E1

Recruitment and retention details.

Fig E2

Distribution of the mite allergen Der p 1. A, Concentration of allergen in reservoir dust samples. B, Quantity of allergen settling in a Petri dish over 10 weeks.

Fig E3

Distribution of serum vitamin D levels (n = 52). The serum concentration of 25-hydroxyvitamin D (25-OHD) recommended in a National position statement for optimal musculoskeletal health is ≥50 nmol/L.

Fig E4

Distribution of hRV titers determined by means of quantitative RT-PCR in nasal and breath samples, which were subsequently able or not able to be genotyped in a nested PCR assay.