Occurrence of virus-induced COPD exacerbations during four seasons

In this study, we investigated the occurrence of viral infections in acute exacerbations of chronic obstructive pulmonary disease (COPD) during four seasons. Viral infections were detected by the use of real-time reverse transcriptase polymerase chain reaction on pharyngeal swabs. During a 12-month period pharyngeal swabs were obtained in 136 exacerbations of 63 patients. In 35 exacerbations (25.7%) a viral infection was detected. Most viral infections occurred in the winter (n = 14, 40.0%), followed by summer (n = 9, 25.7%), autumn (n = 6, 17.1%), and spring (n = 6, 17.1%). Rhinovirus was the most frequently isolated virus (n = 19, 51.4%), followed by respiratory syncytial virus (n = 6, 16.2%), human metapneumovirus (n = 5, 13.5%), influenza A (n = 4, 10.8%), parainfluenza 4 (n = 2, 5.4%), and parainfluenza 3 (n = 1, 2.7%). This study showed that virus-induced COPD exacerbations occur in all four seasons with a peak in the winter months. However, the distribution of rhinovirus infections showed a different pattern, with most infections occurring in July.