title: Pork implicated in a Shiga toxin-producing Escherichia coli O157:H7 outbreak in Ontario, Canada.
abstract: OBJECTIVE
  To describe an outbreak of Shiga toxin-producing Escherichia coli (STEC) O157:H7 infection following a four-day family gathering in Ontario. This is the first published account of a STEC O157 outbreak in Canada linked to consumption of pork.
  
  
  METHODS
  The outbreak investigation included interviews with food handlers and other key associated persons, inspection of food preparation premises, traceback investigations, case finding, analysis of data from an outbreak questionnaire, and laboratory analysis of samples collected from various sources associated with the outbreak.
  
  
  RESULTS
  Several meals, including pork from a pig roast, were served to the 59 attendees, 29 of whom developed gastrointestinal illness following the event. Six cases developed bloody diarrhoea and seven were hospitalized. Leftover pork served the day after the pig roast was the item most significantly associated with an increased risk of illness (p<0.001). STEC O157:H7 was isolated from 11 of the 29 ill attendees, and also from the pork. By pulse-field gel electrophoresis (PFGE), all STEC O157:H7 pork isolates were either identical or closely related to the 11 clinical isolates. No STEC was detected in any other samples. Three Clostridium perfringens isolates, unrelated by PFGE, were obtained from two STEC-positive cases and the pork.
  
  
  CONCLUSIONS
  This outbreak highlights the need for increased awareness of pork as a potential source of STEC O157 infection, and for enhanced education regarding the safe handling, cooking and storage of food, specifically where large cuts of meat are cooked outdoors at events such as pig roasts, a cultural norm in some communities.
authors.affiliation: Wellington-Dufferin-Guelph Public Health, Guelph, ON. Lise.Trotz-Williams@wdgpublichealth.ca
authors.forename: Lise A
authors.initials: LA
authors.lastname: Trotz-Williams
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Mercer
authors.forename: Janice M
authors.initials: JM
authors.lastname: Walters
authors.forename: Anne M
authors.initials: AM
authors.lastname: Maki
authors.forename: Roger P
authors.initials: RP
authors.lastname: Johnson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D004927:Escherichia coli Infections / Q000453:epidemiology*; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D005260:Female; D005511:Food Handling; D005516:Food Microbiology; D006801:Humans; D007223:Infant; D008297:Male; D008460:Meat / Q000382:microbiology*; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D036301:Qualitative Research; D054323:Shiga-Toxigenic Escherichia coli / Q000302:isolation & purification*; D013552:Swine; D055815:Young Adult
keywords: Escherichia coli O157; food-borne illnesses; outbreaks; pigs; pork; zoonoses