title: Respiratory viruses associated with community-acquired pneumonia in children: matched case-control study.
abstract: BACKGROUND
  Community-acquired pneumonia (CAP) is the leading cause of death in children worldwide and a substantial proportion of childhood CAP is caused by viruses. A better understanding of the role of virus infections in this condition is needed to improve clinical management and preventive measures. The aim of the study was therefore to assess the association between specific respiratory viruses and childhood CAP.
  
  
  METHODS
  A case-control study was conducted during 3 years in Stockholm, Sweden. Cases were children aged ≤5 years with radiological CAP. Healthy controls were consecutively enrolled at child health units during routine visits and matched to cases on age and calendar time. Nasopharyngeal aspirates were obtained and analysed by real-time PCR for 15 viruses. Multivariate conditional logistic regression was used to account for coinfections with other viruses and baseline characteristics.
  
  
  RESULTS
  A total of 121 cases, of which 93 cases met the WHO criteria for radiological pneumonia, and 240 controls were included in the study. Viruses were detected in 81% of the cases (n=98) and 56% of the controls (n=134). Influenza virus, metapneumovirus and respiratory syncytial virus were detected in 60% of cases and were significantly associated with CAP with ORs >10. There was no association with parainfluenza virus, human enterovirus or rhinovirus and coronavirus and bocavirus were negatively associated with CAP.
  
  
  CONCLUSIONS
  Our study indicates viral CAP is an underestimated disease and points out hMPV as a new important target for the prevention of childhood CAP.
authors.affiliation: Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Samuel
authors.initials: S
authors.lastname: Rhedin
authors.affiliation: The Public Health Agency of Sweden, Stockholm, Sweden Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Ann
authors.initials: A
authors.lastname: Lindstrand
authors.affiliation: Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Annie
authors.initials: A
authors.lastname: Hjelmgren
authors.affiliation: Department of Clinical Science and Education, Karolinska Institutet, Sachs' Children and Youth Hospital, South General Hospital, Stockholm, Sweden.
authors.forename: Malin
authors.initials: M
authors.lastname: Ryd-Rinder
authors.affiliation: Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Öhrmalm
authors.affiliation: Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden The Public Health Agency of Sweden, Stockholm, Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Tolfvenstam
authors.affiliation: Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden Department of Communicable Disease and Control, Stockholm County Council, Stockholm, Sweden.
authors.forename: Åke
authors.initials: Å
authors.lastname: Örtqvist
authors.affiliation: Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Rotzén-Östlund
authors.affiliation: Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Benita
authors.initials: B
authors.lastname: Zweygberg-Wirgart
authors.affiliation: Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Birgitta
authors.initials: B
authors.lastname: Henriques-Normark
authors.affiliation: Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Kristina
authors.initials: K
authors.lastname: Broliden
authors.affiliation: Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Pontus
authors.initials: P
authors.lastname: Naucler
mesh_terms: D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000821:virology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011024:Pneumonia, Viral / Q000821:virology*; D060888:Real-Time Polymerase Chain Reaction; D013548:Sweden / Q000453:epidemiology
keywords: Clinical Epidemiology; Paediatric Physician; Pneumonia; Viral infection