The severity of bronchiolitis is not dependent on the co-infection of RSV with other respiratory viruses

Bronchiolitis is one of the most common lower respiratory diseases in infants. A correlation between the severity of bronchiolitis and a co-infection with respiratory syncytial virus (RSV) as well as other viruses has not yet been elucidated. The purpose of this study was to clarify the impact of RSV co-infection with other viruses on the severity of bronchiolitis and airway inflammation. One hundred and twelve hospitalized children with clinical symptoms of bronchiolitis were prospectively enrolled in this study. Nasopharyngeal aspirates were analyzed to identify RSV, human bocavirus, human metapneumovirus and nine other respiratory viral pathogens. Inflammatory cell counting and concentrations of cytokines/chemokines were also evaluated. The severity of the disease was further determined on the basis of symptom score and duration of hospitalization. Viral pathogens were detected in 84 samples (75%). RSV was detected in 62 samples (55.36%), 31 of which also possessed other viruses. No difference was found between children with bronchiolitis that had RSV as the sole infecting viral agent and those that were infected with RSV and other viruses with respect to the prevalence of symptoms prior to admission to the hospital, the duration of hospitalization and the diagnosis of severe bronchiolitis. The median cellularity, concentrations of cytokines and cell counts of nasopharyngeal aspirates were similar between the two groups of children. The severity of bronchiolitis is not dependent on the co-infection of RSV with other respiratory viruses.