title: Incidence, molecular epidemiology and clinical presentations of human metapneumovirus; assessment of its importance as a diagnostic screening target.
abstract: BACKGROUND
  Human metapneumovirus (HMPV) is a recently discovered human paramyxovirus associated with a spectrum of respiratory symptoms from the common cold to pneumonia and bronchiolitis.
  
  
  OBJECTIVE
  To assess the clinical significance and epidemiology of HMPV, standardized comparison of frequencies of infection, age profiles and disease associations were made with other respiratory viruses in Scotland.
  
  
  METHODS
  7091 respiratory samples collected in Scotland between 1 July 2006 and 30 June 2008 from 4282 individuals were screened by multiplex RT-PCR for respiratory syncytial virus (HRSV), adenovirus (AdV), parainfluenza viruses 1-3 (PIV-1, -2 and -3), influenza A and B and by nested RT-PCR for HMPV.
  
  
  RESULTS
  HMPV was the fifth most prevalent virus (2.0% of samples), found predominantly in young children in winter months. In the 2006-2007 respiratory season, 70% of HMPV isolates were genotype A, but a switch to predominantly type B infections occurred next winter. For samples with information on clinical presentations, 26% of HMPV infections were from subjects with lower respiratory tract presentations, lower than recorded for HRSV, but similar to adenovirus, parainfluenza viruses and influenza viruses A and B. Around 13% of HMPV infections were associated with upper respiratory tract symptoms or disease, comparable with other respiratory virus infections.
  
  
  CONCLUSIONS
  Numerically and through its association with respiratory disease, HMPV represents a diagnostically significant target that should be included in PCR-based routine screening of respiratory samples. Understanding the biological basis of observed rapid turnover of HMPV variants, including the observed HMPV genotype change between respiratory seasons requires further longitudinal studies.
authors.affiliation: Centre for Infectious Diseases, University of Edinburgh, Edinburgh, United Kingdom. E.Gaunt@sms.ed.ac.uk
authors.forename: Eleanor
authors.initials: E
authors.lastname: Gaunt
authors.forename: E Carol
authors.initials: EC
authors.lastname: McWilliam-Leitch
authors.forename: Kate
authors.initials: K
authors.lastname: Templeton
authors.forename: Peter
authors.initials: P
authors.lastname: Simmonds
mesh_terms: D000256:Adenoviridae / Q000302:isolation & purification; D006801:Humans; D015994:Incidence; D029121:Metapneumovirus / Q000302:isolation & purification*; D017720:Molecular Epidemiology; D009975:Orthomyxoviridae / Q000302:isolation & purification; D018184:Paramyxoviridae Infections / Q000175:diagnosis* / Q000453:epidemiology* / Q000821:virology; D010802:Phylogeny; D018113:Respiratory Syncytial Virus, Human; D012141:Respiratory Tract Infections / Q000175:diagnosis* / Q000453:epidemiology* / Q000821:virology; D018108:Respirovirus / Q000302:isolation & purification; D012606:Scotland / Q000453:epidemiology