title: Characterisation of acute respiratory infections at a United Kingdom paediatric teaching hospital: observational study assessing the impact of influenza A (2009 pdmH1N1) on predominant viral pathogens.
abstract: BACKGROUND
  According to the World Health Organisation, influenza A (2009 pdmH1N1) has moved into the post-pandemic phase, but there were still high numbers of infections occurring in the United Kingdom in 2010-11. It is therefore important to examine the burden of acute respiratory infections at a large children's hospital to determine pathogen prevalence, occurrence of co-infection, prevalence of co-morbidities and diagnostic yield of sampling methods.
  
  
  METHODS
  This was a retrospective study of respiratory virus aetiology in acute admissions to a paediatric teaching hospital in the North West of England between 1st April 2010 and 31st March 2011. Respiratory samples were analysed either with a rapid RSV test if the patient had symptoms suggestive of bronchiolitis, followed by multiplex PCR testing for ten respiratory viruses, or with multiplex PCR testing alone if the patient had suspected other ARI. Patient demographics and data regarding severity of illness, presence of co-morbidities and respiratory virus sampling method were retrieved from case notes.
  
  
  RESULTS
  645 patients were admitted during the study period. 82/645 (12.7%) patients were positive for 2009 pdmH1N1, of whom 24 (29.2%) required PICU admission, with 7.3% mortality rate. Viral co-infection occurred in 48/645 (7.4%) patients and was not associated with more severe disease. Co-morbidities were present more frequently in older children, but there was no significant difference in prevalence of co-morbidity between 2009 pdmH1N1 patients and those with other ARI. NPA samples had the highest diagnostic yield with 192/210 (91.4%) samples yielding an organism.
  
  
  CONCLUSIONS
  Influenza A (2009 pdmH1N1) is an ongoing cause of occasionally severe disease affecting both healthy children and those with co-morbidities. Surveillance of viral pathogens provides valuable information on patterns of disease.
authors.affiliation: Wolfson Centre for Personalised Medicine, University of Liverpool, Block A: Waterhouse Building, 1-5 Brownlow Street, Liverpool L69 3GL, England. emilylees@doctors.org.uk.
authors.forename: Emily A
authors.initials: EA
authors.lastname: Lees
authors.forename: Enitan D
authors.initials: ED
authors.lastname: Carrol
authors.forename: Christine
authors.initials: C
authors.lastname: Gerrard
authors.forename: Fiona
authors.initials: F
authors.lastname: Hardiman
authors.forename: Gareth
authors.initials: G
authors.lastname: Howel
authors.forename: Alison
authors.initials: A
authors.lastname: Timmis
authors.forename: Kent
authors.initials: K
authors.lastname: Thorburn
authors.forename: Malcolm
authors.initials: M
authors.lastname: Guiver
authors.forename: Paul S
authors.initials: PS
authors.lastname: McNamara
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D060085:Coinfection / Q000453:epidemiology; D015897:Comorbidity; D004739:England; D006776:Hospitals, Pediatric; D006784:Hospitals, Teaching; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification / Q000472:pathogenicity; D007251:Influenza, Human / Q000453:epidemiology; D060885:Multiplex Polymerase Chain Reaction; D016133:Polymerase Chain Reaction / Q000379:methods; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000821:virology*; D012189:Retrospective Studies; D012621:Seasons; D014780:Viruses / Q000235:genetics / Q000472:pathogenicity