title: An outbreak of E. coli O157:H7 hemorrhagic colitis associated with unpasteurized gouda cheese.
abstract: BACKGROUND
  A cluster of E. coli O157:H7 hemorrhagic colitis was identified in metro Edmonton, Alberta through notifiable disease surveillance in late 2002.
  
  
  METHODS
  Environmental health officers collected food histories and clinical information from cases in the cluster. The provincial public health laboratory conducted pulsed field gel electrophoresis (PFGE) analysis on E. coli O157:H7 isolates from cluster cases. Public health and food regulatory agencies conducted an investigation when a food source (unpasteurized gouda cheese) was implicated.
  
  
  RESULTS
  PFGE analysis revealed an "outbreak" profile in 13 cases. Onset dates for the outbreak cases ranged between October 2002 and February 2003. Two cases, aged 22 months and 4 years, developed hemolytic uremic syndrome as a result of their infection. Consumption of unpasteurized gouda cheese produced at a local dairy farm was reported by 12 of 13 outbreak cases in the 2 to 8 days prior to illness. E. coli O157:H7 was isolated from 2 of 26 cheese samples manufactured by the implicated producer. The cheese isolates had indistinguishable PFGE profiles as compared with outbreak case isolates. Implicated cheese was found to be contaminated with E. coli O157:H7 104 days after production, despite having met regulated microbiological and aging requirements.
  
  
  CONCLUSIONS
  To our knowledge, this is the first confirmed outbreak of E. coli O157:H7 infection in Canada associated with raw milk hard cheese. A review of federal legislation vis-à-vis raw milk hard cheese may be in order.
authors.affiliation: Capital Health-Public Health Division, Edmonton, Alberta. lhonish@cha.ab.ca
authors.forename: Lance
authors.initials: L
authors.lastname: Honish
authors.forename: Gerry
authors.initials: G
authors.lastname: Predy
authors.forename: Nyall
authors.initials: N
authors.lastname: Hislop
authors.forename: Linda
authors.initials: L
authors.lastname: Chui
authors.forename: Kinga
authors.initials: K
authors.lastname: Kowalewska-Grochowska
authors.forename: Larry
authors.initials: L
authors.lastname: Trottier
authors.forename: Cornelia
authors.initials: C
authors.lastname: Kreplin
authors.forename: Ingrid
authors.initials: I
authors.lastname: Zazulak
mesh_terms: D000416:Alberta / Q000453:epidemiology; D002611:Cheese / Q000382:microbiology*; D016000:Cluster Analysis; D003092:Colitis / Q000453:epidemiology / Q000382:microbiology*; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology; D005511:Food Handling; D005516:Food Microbiology; D006471:Gastrointestinal Hemorrhage / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans