Role of viruses in exacerbations of chronic obstructive pulmonary disease.

Exacerbations of chronic obstructive pulmonary disease (COPD) are a major cause of morbidity and mortality and hospital admission. Respiratory viral infections, especially rhinoviruses, are a major cause of COPD exacerbations, with upper respiratory tract infections being associated with over 50% of COPD exacerbations. The presence of an upper respiratory tract infection leads to a more severe exacerbation and a longer symptom recovery time at exacerbation. Respiratory viral infections occurring during COPD exacerbations are more likely to lead to hospitalization. Sputum inflammatory markers were found to be higher in those patients with symptoms of a common cold or where rhinovirus was detected at exacerbation, thus suggesting that viral infections lead to greater airway inflammation and thus more severe exacerbations. COPD exacerbations are associated also with systemic inflammatory effects with increases in markers such as plasma fibrinogen and interleukin-6. Respiratory viruses have also been detected when the patients are stable, and this suggests that chronic viral infection may occur. Strategies to prevent viral infection will have a significant effect on the morbidity of COPD and will improve quality of life.