title: Epidemiology of Haemophilus influenzae bacteremia: a multi-national population-based assessment.
abstract: OBJECTIVE
  Haemophilus influenzae is an important cause of invasive infection but contemporary data in non-selected populations is limited.
  
  
  METHODS
  Population-based surveillance for Haemophilus influenzae bacteremia was conducted in seven regions in Australia, Canada, and Denmark during 2000-2008.
  
  
  RESULTS
  The overall annual incidence rate was 1.31 per 100,000 population and type specific rates were 0.08 for H. influenzae serotype b (Hib), 0.22 for H. influenzae serotypes a, c-f (Hiac-f), and 0.98 per 100,000 for non-typeable H. influenzae (NTHi). Very young and old patients were at highest risk. The serotypes causing disease varied according to age with nearly all cases in the elderly due to NTHi. The presence of comorbid medical illness was common with 14%, 16%, and 29% patients having Charlson comorbidity scores of 1, 2, and ≥ 3, respectively. The 30-day all-cause case-fatality rate was 18%. Factors independently associated with death at 30-days in logistic regression analysis included male gender, hospital-onset disease, older age, and lower respiratory tract, central nervous system, or unknown focus of infection.
  
  
  CONCLUSIONS
  Haemophilus influenzae is an important cause of morbidity and mortality particularly with NTHi in the elderly. These data serve as a baseline to assess the future effectiveness of new preventative interventions.
authors.affiliation: Department of Medicine, University of Calgary, Calgary, Alberta, Canada. Kevin.laupland@calgaryhealthregion.ca
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Laupland
authors.forename: Henrik C
authors.initials: HC
authors.lastname: Schønheyder
authors.forename: Christian
authors.initials: C
authors.lastname: Østergaard
authors.forename: Jenny Dahl
authors.initials: JD
authors.lastname: Knudsen
authors.forename: Louis
authors.initials: L
authors.lastname: Valiquette
authors.forename: John
authors.initials: J
authors.lastname: Galbraith
authors.forename: Karina J
authors.initials: KJ
authors.lastname: Kennedy
authors.forename: Kim O
authors.initials: KO
authors.lastname: Gradel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia / Q000453:epidemiology; D016470:Bacteremia / Q000453:epidemiology* / Q000401:mortality; D002170:Canada / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006192:Haemophilus Infections / Q000453:epidemiology* / Q000401:mortality*; D006193:Haemophilus influenzae; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012307:Risk Factors; D012703:Serotyping