Association of viral and Mycoplasma pneumoniae infections with acute respiratory illness in patients with chronic obstructive pulmonary diseases.

The relative importance of respiratory virus and M. pneumoniae infections as causes of acute respiratory illnesses was studied over an 8 yr period in 150 subjects who were normal or who had varying degrees of chronic obstructive pulmonary disease (COPD). Viral or M. pneumoniae infections were associated with 186 of 1,030 (18%) illnesses studied, whereas these infections were detected in only 86 of 1,398 (6%) illness-free periods (P less than 0.01). Rhinoviruses, influenza viruses, parainfluenza viruses and coronaviruses were each significantly associated with acute respiratory illnesses. The occurrence of acute respiratory illnesses and viral infections was the same in subjects with moderate to severe COPD as it was in subjects who were normal or who had mild disease.