Viral Infections and Associated Factors That Promote Acute Exacerbations of Asthma

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.

Updates in the Relationship Between Human Rhinovirus and Asthma

Human rhinovirus (HRV) is a nonenveloped, single stranded RNA virus belonging to the family Picornaviridae. HRV infections can cause both upper and lower respiratory illnesses in children and adults. Lower respiratory illnesses are more likely to occur in specific high risk groups, including infants, and children and adults with asthma. The relationships between rates of infection and the risk of clinical illness and exacerbation are not completely understood. Recent studies employing polymerase chain reaction and other molecular techniques indicate that there are new branches on the HRV family tree, and one characteristic of recently detected viruses is that they cannot be detected by standard tissue culture. Here we review the current literature and discuss new advances in understanding the link between HRV and asthma.