Weekly monitoring of children with asthma for infections and illness during common cold seasons

Abstract

Background Exacerbations of childhood asthma and rhinovirus infections both peak during the spring and fall, suggesting that viral infections are major contributors to seasonal asthma morbidity. Objectives To evaluate rhinovirus infections during peak seasons in children with asthma, and to analyze relationships between viral infection and illness severity. Methods Fifty-eight children with asthma ages 6-8 years provided 5 consecutive weekly nasal lavage samples during September and April; symptoms, medication use, and peak flow were recorded. Rhinoviruses were identified using multiplex PCR and partial sequencing of viral genomes. Results Viruses were detected in 36-50% of the specimens, and, 72-99% of the viruses were rhinoviruses. There were 52 different strains (including 16 HRV-C) among the 169 rhinovirus isolates; no strains found in more than two collection periods, and all but two children had a respiratory infection. Virus-positive weeks were associated with greater cold and asthma severity (p<0.0001 and p=0.0002 respectively). Furthermore, virus-positive illnesses had increased duration and severity of cold and asthma symptoms, and more frequent loss of asthma control (47% vs. 22%, p=0.008). While allergen-sensitized vs. non-sensitized children had the same number of viral infections, the former had 47% more symptomatic viral illnesses (1.19 vs. 0.81 per month, p=0.03). Conclusions Rhinovirus infections are nearly universal in children with asthma during common cold seasons, likely due to a plethora of new strains appearing each season. Illnesses associated with viruses have greater duration and severity. Finally, atopic asthmatic children experienced more frequent and severe viral-induced illnesses. Clinical Implications The combination of viral infection and allergy increases the morbidity of respiratory illness in children with asthma.