Severe Asthma Not Linked to Persistent Viral Presence

Respiratory virus detection rates in severe and stable asthma similar to healthy controls

FRIDAY, July 15 (HealthDay News) -- Respiratory-virus detection rates in the airways of patients with clinically stable and severe asthma are not significantly different from those of healthy controls, according to a study published in the August issue of Allergy.

Viviana Turchiarelli, M.D., from the University of Amsterdam in the Netherlands, and colleagues investigated whether the presence of viruses in the airways of patients with clinically severe but stable asthma is more persistent and prolonged than patients with mild asthma and healthy controls. A total of 35 patients who had no cold symptoms for more than four weeks were divided into three groups: clinically stable mild asthma (12), severe asthma (12), and healthy controls (11). All participants completed a questionnaire on asthma symptoms, and a spirometry test at baseline. Nasal and throat swabs, induced sputum samples, exhaled breath condensate, and gelatine filled expired air from positive and negative controls were assayed by polymerase chain reaction for 14 respiratory viruses at zero, six, and 12 weeks.

The investigators found that 32 of the 525 patient evaluations had positive virus samples, with human rhinovirus, adenovirus, respiratory syncytial virus, parainfluenza 3 & 4, human bocavirus, influenza B and coronavirus detected. On average, 18 percent of controls and 30 percent of patients with mild and severe asthma tested positive for a virus when all sampling methods were combined, with no difference between the groups. Based on longitudinal data the viral presence over time was changing rather than persistent.

"These findings suggest that the maintenance and chronicity of asthma is not linked to persistent viral presence in the airways," the authors write.

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