Asthma and Infections: An Update on Asthma ExacerbationsSykes, Annemarie MBBS, PhDClinical Pulmonary Medicine: March 2013 - Volume 20 - Issue 2 - p 56–60 doi: 10.1097/CPM.0b013e318285c4e0 Obstructive Airways Disease Abstract Author Information Asthma is common, affecting approximately 300 million people of all ages globally and the incidence is increasing in many countries. Although stable asthma is a problem, the majority of mortality morbidity and health care expenditure is associated with asthma exacerbations. The majority of asthma exacerbations are related to respiratory virus infections, particularly rhinovirus, and asthmatic airways may have a defective interferon response to rhinovirus infection. This review summarizes the current literature on the role of viruses, evidence for defective interferon induction in asthma, and suggests a potential role for bacteria in asthma exacerbations. National Heart & Lung Institute, Imperial College London, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, Centre for Respiratory Infection, Imperial Healthcare NHS Trust, London, UK Supported by grants from the Medical Research Council (MRC Clinical Research Fellowship) and Clinical Lecturer funding schemes. The author declares that there is nothing to disclose. Address correspondence to: Annemarie Sykes, MBBS, PhD, Imperial College London, Norfolk Place W2 1PG, UK. E-mail: email@example.com. © 2013 Lippincott Williams & Wilkins, Inc.