Role of viral infections in the development and exacerbation of asthma in children

Wheezing is a common complaint among parents of infants.  About 1 in 5 children have acute wheezing illnesses in their first two years of life.  This is important because an overwhelming majority of these wheezing illnesses are related to viruses, and are linked to asthma development.  In this month’s issue of JACI, Jartti and Gern review the role of viral infections in the development of asthma in children (J Allergy Clin Immunol 2017; 140(4): 895-906). 

They survey the viruses -rhinoviruses, respiratory syncytial viruses, and others – and how they impact the developing set of lungs.  Genetic variation and low interferon responses are two factors that increase the risk of these types of infections.  In addition, increased eosinophil counts in blood and nasal mucus and atopic eczema all increase the risk of later asthma. 

Additionally, viral infections can lead to exacerbations in children who already have asthma.  This may explain why the rates of asthma exacerbations are higher during the fall and winter, and why omalizumab, a potent medication for asthma control, may help to prevent exacerbations due to viruses like rhinovirus.  The authors conclude that these insights may allow for new strategies to help prevent and manage viral wheezing illnesses so that they don’t lead to and worsen later asthma.

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