Viral infection and allergy status impact severity of asthma symptoms in children with asthma exacerbations.

BACKGROUND: Although viral infection is known to be associated with asthma exacerbations, prior research has not identified reliable predictors of acute symptom severity in virus-related asthma exacerbations (VRAEs). OBJECTIVE: To determine the effect of asthma control and viral infection on the severity of current illness and evaluate biomarkers related to acute symptoms during asthma exacerbations. METHODS: We prospectively enrolled 120 children with physician-diagnosed asthma and current wheezing who presented to Arkansas Children's Hospital emergency department. The asthma control test (ACT) stratified controlled (ACT > 19) and uncontrolled (ACT ≤ 19) asthma, whereas pediatric respiratory symptom scores evaluated symptoms. Nasopharyngeal swabs were obtained for viral analysis, and inflammatory mediators were evaluated by nasal filter paper and Luminex assays. RESULTS: There were 33 children with controlled asthma and 87 children with uncontrolled asthma. In those with uncontrolled asthma, 77% were infected with viruses during VRAE compared with 58% of those with controlled asthma. Uncontrolled subjects with VRAE had more acute symptoms compared with the controlled subjects with VRAE or uncontrolled subjects without a virus. The uncontrolled subjects with VRAE and allergy had the highest acute symptom scores (3.363 point pediatric respiratory symptom; P = .04). Children with asthma with higher symptom scores had more periostin (P = .02). CONCLUSION: Detection of respiratory viruses is frequent in those with uncontrolled asthma. Uncontrolled subjects with viruses have more acute symptoms during exacerbations, especially in those with allergy. Periostin was highest in subjects with the most acute symptoms, regardless of control status. Taken together, these data imply synergy between viral infection and allergy in subjects with uncontrolled asthma when considering acute asthma symptoms and nasal inflammation during an exacerbation of asthma.

Rhinovirus and Asthma Exacerbations.

Rhinovirus (RV) is ubiquitous and typically causes only minor upper respiratory symptoms. However, especially in children and adolescent asthmatics, RV is responsible for most exacerbations. This ability of RV to drive exacerbations typically requires the concomitant presence of exposure to a bystander allergen. Susceptibility to RV-mediated exacerbations is also related to the genetic background of the host, which contributes to greater infectivity, more severe infections, altered immune responses, and to greater inflammation and loss of asthma control. Given these responses, there are several treatments available or being developed that should improve the control of exacerbations related to RV infection.