Association of specific viral infections with childhood asthma exacerbations

Hassanzad, Maryam; Nadji, Seyed Alireza; Darougar, Sepideh; Tashayoie-Nejad, Sabereh; Boloursaz, Mohammad Reza; Mahdaviani, Seyed Alireza; Baghaie, Nooshin; Ghaffaripour, Hosseinali; Velayati, Ali Akbar

Asthma is the most common chronic respiratory disease associated with an increasing prevalence characterized by airway inflammation, mucus production, and airway hyperresponsiveness [1] . Bronchial hyperresponsiveness may occur in response to many common environmental triggers [2, 3] leading to asthma exacerbations. Asthma exacerbations are acute or subacute worsening episodes of shortness of breath, coughing, wheezing, and chest tightness [4] , which are classified as mild, moderate, severe, or life-threatening. These exacerbations may be associated with a variety of respiratory viruses, including human rhinovirus (HRV), respiratory syncytial virus (RSV), influenza virus, parainfluenzavirus, human metapneumovirus, adenovirus, bocavirus, and coronavirus [5] , of which the first two mentioned groups are most importantly relevant to asthma development [6] . Viral respiratory infections are usually self-limiting illnesses [4] . However, they may exert profound effects on important aspects of asthma [7] . Studies suggest a substantial role for viral infections in about 50% of asthma exacerbations