title: Increasing incidence of invasive group A streptococcus disease in New Zealand, 2002-2012: a national population-based study.
abstract: OBJECTIVE
  To analyse the incidence, demographics and molecular epidemiology of invasive group A streptococcal (GAS) disease in New Zealand between 2002 and 2012.
  
  
  METHODS
  Using laboratory-based surveillance data, invasive GAS isolates were identified from the Institute of Environmental Science and Research, New Zealand. Hospitalization and mortality data were obtained from the New Zealand Ministry of Health. Molecular typing was performed by sequence analysis of the emm gene.
  
  
  RESULTS
  The incidence of invasive GAS infections increased from 3.9 per 100,000 population in 2002 to 7.9 per 100,000 population (P < 0.001) in 2012. The incidence was highest in the over 75-year age group, and in Pacific peoples. There was temporal variation in emm types associated with invasive GAS disease, with emm1 being the overall predominant emm type. The diversity of emm types varied significantly according to ethnicity. Overall, 59% of GAS isolates were theoretically covered by an experimental M-protein vaccine.
  
  
  CONCLUSIONS
  Our study provides valuable data on the epidemiology of invasive GAS disease in New Zealand, and represents one of the few studies to assess such longitudinal data across an entire nation. The increase in invasive GAS disease is concerning, and reasons for this should be explored further.
authors.affiliation: Institute of Environmental Science and Research, Wellington, New Zealand; University of Auckland, Auckland, New Zealand. Electronic address: deb.williamson@auckland.ac.nz.
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Williamson
authors.affiliation: Institute of Environmental Science and Research, Wellington, New Zealand.
authors.forename: Julie
authors.initials: J
authors.lastname: Morgan
authors.affiliation: Institute of Environmental Science and Research, Wellington, New Zealand.
authors.forename: Virginia
authors.initials: V
authors.lastname: Hope
authors.affiliation: University of Auckland, Auckland, New Zealand.
authors.forename: John D
authors.initials: JD
authors.lastname: Fraser
authors.affiliation: University of Auckland, Auckland, New Zealand.
authors.forename: Nicole J
authors.initials: NJ
authors.lastname: Moreland
authors.affiliation: University of Auckland, Auckland, New Zealand.
authors.forename: Thomas
authors.initials: T
authors.lastname: Proft
authors.affiliation: Institute of Environmental Science and Research, Wellington, New Zealand.
authors.forename: Graham
authors.initials: G
authors.lastname: Mackereth
authors.affiliation: Institute of Environmental Science and Research, Wellington, New Zealand.
authors.forename: Diana
authors.initials: D
authors.lastname: Lennon
authors.affiliation: University of Otago, Wellington, New Zealand.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Baker
authors.affiliation: Institute of Environmental Science and Research, Wellington, New Zealand.
authors.forename: Philip E
authors.initials: PE
authors.lastname: Carter
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D009520:New Zealand / Q000453:epidemiology; D018805:Sepsis; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology* / Q000401:mortality; D013297:Streptococcus pyogenes; D055815:Young Adult
keywords: Epidemiology; Sepsis; Streptococcal disease