Respiratory syncytial virus and adenovirus in acute lower respiratory infections in hospitalized infants and children

Background: Lower respiratory tract infection (LRTI) is a main cause of hospitalization in infants and children. These patients’ nasopharyngeal swabs more frequently contain respiratory syncytial virus (RSV) than human adenovirus (HAdV) in cold seasons; recent data suggest that oropharyngeal swabs more frequently contain HAdV than RSV. Knowing more about virus detection with oropharyngeal swabs, seasonal fluctuations and age-related distribution of RSV and HAdV would help treat children hospitalized for LRTI more effectively. We investigated the seasonal virus-related frequency (as assessed by oropharyngeal swabs) and environmental and clinical features in infants and children hospitalized for LRTI from autumn to spring. Methods: We studied 98 subjects hospitalized for LRTI in our Pediatric Unit, from November 2006 to May 2007. RSV and HAdV in oropharyngeal swabs were assessed by real-time polymerase chain reaction (PCR) assay. Results: PCR assays more frequently detected HAdV (29.6% of patients) than RSV (25.5%). The seasonal incidence also differed (RSV, narrow peak in December and HAdV, wide peak from April to May). Most patients infected with RSV were aged 2 yrs or younger (23/25: 88%); no difference was found in age between subjects who tested HAdV-positive (13/29: 45%) or undetectable-virus (23/44: 52%). Bronchiolitis was more frequently associated with RSV than HAdV or undetectable-virus oropharyngeal swabs. No difference was found in risk factors (school attendance, atopic parents, exposure to cigarette smoking, home dampness or exposure to animals) or clinical features (vital parameters or duration of hospital stay) among the three viral groups. Conclusions: Our findings show a high frequency of HAdV-positive oropharyngeal swabs during acute LRTIs in infants and children and differences in the seasonal distribution of RSV and HAdV in Rome.