title: Detection of influenza C virus but not influenza D virus in Scottish respiratory samples.
abstract: BACKGROUND
  A newly proposed genus of influenza virus (influenza D) is associated with respiratory disease in pigs and cattle. The novel virus is most closely related to human influenza C virus and can infect ferrets but infection has not been reported in humans.
  
  
  OBJECTIVE
  To ascertain if influenza D virus can be detected retrospectively in patient respiratory samples.
  
  
  METHODS
  3300 human respiratory samples from Edinburgh, Scotland, covering the period 2006-2008, were screened in pools of 10 by RT-PCR using primers capable of detecting both influenza C and D viruses.
  
  
  RESULTS
  Influenza D was not detected in any sample. Influenza C was present in 6 samples (0.2%), compared with frequencies of 3.3% and 0.9% for influenza A and B viruses from RT-PCR testing of respiratory samples over the same period. Influenza C virus was detected in samples from individuals <2 years or >45 years old, with cases occurring throughout the year. Phylogenetic analysis of nearly complete sequences of all seven segments revealed the presence of multiple, reassortant lineages.
  
  
  CONCLUSIONS
  We were unable to detect viruses related to influenza D virus in human respiratory samples. Influenza C virus was less prevalent than influenza A and B viruses, was associated with mild disease in the young (<2 years) and old (>45 years) and comprised multiple, reassortant lineages. Inclusion of influenza C virus as part of a diagnostic testing panel for respiratory infections would be of limited additional value.
authors.affiliation: Centre for Immunology, Infection and Evolution, University of Edinburgh, Ashworth Laboratories, Kings Buildings, West Mains Road, Edinburgh EH9 3JT, United Kingdom. Electronic address: D.B.Smith@ed.ac.uk.
authors.forename: Donald B
authors.initials: DB
authors.lastname: Smith
authors.affiliation: The Roslin Institute Building, The University of Edinburgh, Easter Bush Campus, Midlothian, EH25 9RG, United Kingdom.
authors.forename: Eleanor R
authors.initials: ER
authors.lastname: Gaunt
authors.affiliation: The Roslin Institute Building, The University of Edinburgh, Easter Bush Campus, Midlothian, EH25 9RG, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Digard
authors.affiliation: Department of Virology, Royal Infirmary of Edinburgh, 51 Little France Crescent, Old Dalkeith Road, Edinburgh EH16 4SA, United Kingdom.
authors.forename: Kate
authors.initials: K
authors.lastname: Templeton
authors.affiliation: The Roslin Institute Building, The University of Edinburgh, Easter Bush Campus, Midlothian, EH25 9RG, United Kingdom.
authors.forename: Peter
authors.initials: P
authors.lastname: Simmonds
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D009982:Gammainfluenzavirus / Q000302:isolation & purification*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000821:virology*; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012606:Scotland / Q000453:epidemiology; D018117:Thogotovirus / Q000302:isolation & purification*
keywords: Influenza C virus; Respiratory disease