title: Changing Patterns of Pertussis in a Children's Hospital in the Polymerase Chain Reaction Diagnostic Era.
abstract: OBJECTIVE
  To assess changes in diagnostic practice and vaccine schedules for pertussis, we used culture-confirmation and clinical severity to compare pertussis cases at a single Australian tertiary pediatric hospital during relevant periods.
  
  
  METHODS
  We replicated the case ascertainment methods of a study reporting a 2-year epidemic period 1997-1999 (whole cell pertussis vaccine with 18-month booster, only culture available) to conduct a retrospective cross-sectional observational study over a 6-year period 2007-2012 (acellular pertussis vaccine, no 18-month booster, polymerase chain reaction and culture available). Cases were compared from case note review 2007-2012 (including prevalence of comorbidities) and published data 1997-1999.
  
  
  RESULTS
  During 2007-2012, average annual hospitalizations in those aged < 6 months increased 2.3-fold (32.0 vs 14.0) and in those aged > 6 months by 5.1-fold (17.7 vs 3.5). Limited to culture-positive hospitalizations, there was no increase in those aged < 6 months (14.0 vs 14.5) contrasted with a 4.6-fold increase in those aged > 6 months (2.3 vs 0.5), despite increased annual culture requests (488 vs 188). In 2007-2012, significant comorbidities were documented in 41/72 (57%) hospitalized children aged ≥ 12 months vs 38/225 (17%) <12 months (OR 6.5, 95% CI 3.7-11.7).
  
  
  CONCLUSIONS
  Increased cases of culture-positive hospitalized pertussis were limited to fully immunized children > 6 months of age, consistent with schedule changes. Significant comorbidities were common, making a booster dose at 12-18 months of age especially important.
authors.affiliation: National Center for Immunization Research and Surveillance of Vaccine Preventable Diseases, The Children's Hospital at Westmead, Westmead, New South Wales, Australia; Discipline of Pediatrics and Child Health, University of Sydney, The Children's Hospital at Westmead, Westmead, New South Wales, Australia.
authors.forename: Sophie
authors.initials: S
authors.lastname: Hale
authors.affiliation: National Center for Immunization Research and Surveillance of Vaccine Preventable Diseases, The Children's Hospital at Westmead, Westmead, New South Wales, Australia; Discipline of Pediatrics and Child Health, University of Sydney, The Children's Hospital at Westmead, Westmead, New South Wales, Australia.
authors.forename: Helen E
authors.initials: HE
authors.lastname: Quinn
authors.affiliation: Department of Microbiology and Infectious Diseases, The Children's Hospital at Westmead, Westmead, New South Wales, Australia.
authors.forename: Alison
authors.initials: A
authors.lastname: Kesson
authors.affiliation: National Center for Immunization Research and Surveillance of Vaccine Preventable Diseases, The Children's Hospital at Westmead, Westmead, New South Wales, Australia; Discipline of Pediatrics and Child Health, University of Sydney, The Children's Hospital at Westmead, Westmead, New South Wales, Australia; Department of Microbiology and Infectious Diseases, The Children's Hospital at Westmead, Westmead, New South Wales, Australia.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Wood
authors.affiliation: National Center for Immunization Research and Surveillance of Vaccine Preventable Diseases, The Children's Hospital at Westmead, Westmead, New South Wales, Australia; Discipline of Pediatrics and Child Health, University of Sydney, The Children's Hospital at Westmead, Westmead, New South Wales, Australia; Department of Microbiology and Infectious Diseases, The Children's Hospital at Westmead, Westmead, New South Wales, Australia.
authors.forename: Peter B
authors.initials: PB
authors.lastname: McIntyre
mesh_terms: D001886:Bordetella pertussis / Q000235:genetics; D015897:Comorbidity; D003430:Cross-Sectional Studies; D004269:DNA, Bacterial / Q000235:genetics; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D006760:Hospitalization / Q000639:trends*; D006776:Hospitals, Pediatric; D006801:Humans; D007115:Immunization Schedule; D007117:Immunization, Secondary; D007223:Infant; D015278:Intensive Care Units, Pediatric / Q000706:statistics & numerical data; D009517:New South Wales / Q000453:epidemiology; D010567:Pertussis Vaccine; D016133:Polymerase Chain Reaction; D012189:Retrospective Studies; D014917:Whooping Cough / Q000175:diagnosis / Q000453:epidemiology*
chemical_list: D004269:DNA, Bacterial; D010567:Pertussis Vaccine