Viral Infections and Associated Factors That Promote Acute Exacerbations of Asthma

Abstract

Despite asthma being the most common chronic childhood ailment, there is still much to learn about the disease. Early childhood infections with well-known or emerging viruses can lay the pathophysiologic framework for asthma development and exacerbation later in life, which may be due partly to alteration of the airway microbiome. Once asthma is established, acute exacerbations are usually associated with infections with respiratory viruses, such as rhinoviruses (RVs). Once again, there are bidirectional interactions between viruses and airway bacteria that appear to influence the severity of illness and the likelihood of exacerbation. Studies employing recent advances in viral and bacterial identification analytic techniques will clarify these new concepts and may provide the basis for new treatments or prevention or respiratory infection-associated exacerbation. This paper is a review of the associations among respiratory viruses, bacteria, inflammatory mechanisms, and asthma exacerbation.

Keywords: Asthma exacerbation; co-infection; emerging viruses; eosinophils; inflammatory mediators.

Figure. Factors that can influence the severity of RV infections and the risk of RV-induced exacerbations of asthma. In children and adults with asthma, the severity of RV infection is positively related to the probability of exacerbation. Factors that increase the likelihood of more severe RV illnesses and exacerbations of asthma include the species of RV, the presence of bacterial pathogens in the airway, allergic inflammation, and polymorphisms in CDHR3 and the 17q21 region of the genome. RV, rhinovirus; CDHR3, cadherin-related protein-3; IgE, immunoglobulin E; Eos, eosinophils.