Outbreak of Verotoxigenic E. Coli (VTEC): Winnipeg
Increased VTEC activity well over expected amounts was observed in the Winnipeg Health Region (WHR) during the summer of 2006. Seventy-seven (77) cases were reported in the WHR between 1 January and 30 September 2006; 15-20 cases are expected in this time period and only 10-15 cases would be expected in the WHR during the summer period.
Similarly, VTEC cases were elevated during the summer of 2006 in rural Manitoba and in other provinces across Canada. Further analysis by the Public Health Agency of Canada uncovered no common source of VTEC for this increased background level of activity throughout Canada, and no common PFGE strains between provinces.
Two VTEC outbreaks in the USA linked to consumption of contaminated spinach and lettuce respectively were not related to the Winnipeg VTEC outbreak, as they were caused by entirely different VTEC strains (PFGE patterns) not seen in any of the Winnipeg cases.
The working hypothesis created to guide the WRHA public health interventions postulated that VTEC strains possibly originating from the slaughterhouse that owns and supplies a certain processor (processor Y) entered the food chain sometime early in the month of August 2006.
The most likely source would have been a bovine carcass that had been contaminated with fecal material. Further, it was hypothesized that VTECcontaminated meat would have been supplied to a certain retailer (retailer X) by processor Y.
Inadequate cleaning of the industrial grinder and inadequate food handling practices initially observed at retailer X could have amplified and perpetuated VTEC contamination of meat products, increasing the probability that retailer X would have supplied its daily clients (restaurants A, B, C and D) with contaminated raw ground beef.
In addition, restaurant inspection reports revealed that, in some of these restaurants, raw ground beef was stored at improper temperatures that could have resulted in the further amplification of VTEC. Inadequate food handling practices were also observed in all of these restaurants, potentially contributing to the transmission of VTEC to customers through cross-contamination of ground beef-containing and possibly other food products.