title: Clinical utility of PCR for common viruses in acute respiratory illness.
abstract: BACKGROUND
  Acute respiratory illness (ARI) accounts for a large proportion of all visits to pediatric health facilities. Quantitative real-time polymerase chain reaction (qPCR) analyses allow sensitive detection of viral nucleic acids, but it is not clear to what extent specific viruses contribute to disease because many viruses have been detected in asymptomatic children. Better understanding of how to interpret viral findings is important to reduce unnecessary use of antibiotics.
  
  
  OBJECTIVE
  To compare viral qPCR findings from children with ARI versus asymptomatic control subjects.
  
  
  METHODS
  Nasopharyngeal aspirates were collected from children aged ≤5 years with ARI and from individually matched, asymptomatic, population-based control subjects during a noninfluenza season. Samples were analyzed by using qPCR for 16 viruses.
  
  
  RESULTS
  Respiratory viruses were detected in 72.3% of the case patients (n = 151) and 35.4% of the control subjects (n = 74) (P = .001). Rhinovirus was the most common finding in both case patients and control subjects (47.9% and 21.5%, respectively), with a population-attributable proportion of 0.39 (95% confidence interval: 0.01 to 0.62). Metapneumovirus, parainfluenza viruses, and respiratory syncytial virus were highly overrepresented in case patients. Bocavirus was associated with ARI even after adjustment for coinfections with other viruses and was associated with severe disease. Enterovirus and coronavirus were equally common in case patients and control subjects.
  
  
  CONCLUSIONS
  qPCR detection of respiratory syncytial virus, metapneumovirus, or parainfluenza viruses in children with ARI is likely to be causative of disease; detection of several other respiratory viruses must be interpreted with caution due to high detection rates in asymptomatic children.
authors.affiliation: Department of Medicine Solna, Unit of Infectious Diseases, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden;
authors.forename: Samuel
authors.initials: S
authors.lastname: Rhedin
authors.forename: Ann
authors.initials: A
authors.lastname: Lindstrand
authors.forename: Maria
authors.initials: M
authors.lastname: Rotzén-Östlund
authors.forename: Thomas
authors.initials: T
authors.lastname: Tolfvenstam
authors.forename: Lars
authors.initials: L
authors.lastname: Ohrmalm
authors.forename: Malin Ryd
authors.initials: MR
authors.lastname: Rinder
authors.forename: Benita
authors.initials: B
authors.lastname: Zweygberg-Wirgart
authors.forename: Ake
authors.initials: A
authors.lastname: Ortqvist
authors.forename: Birgitta
authors.initials: B
authors.lastname: Henriques-Normark
authors.forename: Kristina
authors.initials: K
authors.lastname: Broliden
authors.forename: Pontus
authors.initials: P
authors.lastname: Naucler
mesh_terms: D000208:Acute Disease; D016022:Case-Control Studies; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D060888:Real-Time Polymerase Chain Reaction / Q000706:statistics & numerical data*; D012136:Respiratory Syncytial Viruses / Q000302:isolation & purification; D012141:Respiratory Tract Infections / Q000175:diagnosis* / Q000235:genetics / Q000821:virology*; D012229:Rhinovirus / Q000302:isolation & purification; D014764:Viral Proteins / Q000302:isolation & purification
chemical_list: D014764:Viral Proteins; C105040:pol protein, Rabbit endogenous retrovirus H
keywords: case-control study; children; etiology; respiratory illness; viral infections