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. 2002 Sep;13(5):321-30.
doi: 10.1155/2002/383840.

Verotoxigenic Escherichia coli (VTEC): a major public health threat in Canada

David L Woodward  1 , Clifford G Clark, Richard A Caldeira, Rafiq Ahmed, Frank G Rodgers
Affiliations

Verotoxigenic Escherichia coli (VTEC): a major public health threat in Canada

David L Woodward et al. Can J Infect Dis. 2002 Sep.

Abstract

Background: Verotoxigenic Escherichia coli (VTEC) was first described in Canada during the 1980s as an emerging foodborne disease in association with morbidity and mortality in outbreaks of hemorrhagic colitis caused by E coli O157:H7.

Objective: To describe the surveillance activities and epidemiological laboratory markers of VTEC that are used at the National Laboratory for Enteric Pathogens (NLEP) to investigate sporadic cases and outbreaks of E coli O157:H7 and non-O157 VTEC in Canada.

Methods: Passive surveillance was conducted by obtaining data on laboratory confirmed cases of VTEC from the Provincial Laboratories of Public Health across Canada. The laboratory epidemiological markers generated for isolates of VTEC included biotyping, serotyping, phage typing, toxin detection and characterization, and molecular typing using pulsed-field gel electrophoresis.

Results: Major outbreaks of VTEC O157:H7 disease have been associated with ground beef, unpasteurized apple juice, salami and untreated water. In 1999 and 2000, a total of 46 outbreaks of E coli O157:H7 disease were investigated. Among those, one outbreak was associated with contact at a petting zoo and a second with the consumption of salami. An outbreak in 2000 in Ontario was associated with water and resulted in more than 1000 cases of human illness, with six deaths. The NLEP has also identified more than 100 non-O157 VTEC serotypes from cattle and meat products. At least 23 VTEC serotypes found in humans were also identical to those found in cattle and meat products.

Conclusions: The laboratory-based information that is generated is used to define the incidence, sources of infection, risk factors, trends, distribution and transmission of VTEC to humans from food, water and animal sources. Prevention and control of outbreaks are high-priority health concerns.

Keywords: Epidemiological markers; Escherichia coli (VTEC); Outbreaks; Verotoxigenic.

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Figures

Figure 1
Figure 1
Human laboratory confirmed cases of Escherichia coli O157:H7 in Canada between 1983 and 2000
Figure 2
Figure 2
Pulsed-field gel electrophoresis (PFGE) of selected non-O157 verotoxin Escherichia coli serotypes found in Canada. Lanes 1, 5, 10 and 15 contain PFGE standard strain G5244. Serotypes of each isolate tested are included below the lane number
Figure 3
Figure 3
Dendrogram distribution of non-O157 verotoxin Escherichia coli in Canada.Pulsed-field gel electrophoresis patterns were analyzed using Molecular Analyst 2.0 (Applied Maths Kortrijk, Belgium). The dendrogram was created using the Dice coefficient by the unweighted pair group method with arithmatic mean method, with a maximum band position tolerance of 1.5%
Figure 4
Figure 4
Pulsed-field gel electrophoresis (PFGE) of the Escherichia coli O157:H7 outbreak associated with salami that affected three provinces in Canada. Lanes 1, 5, 10 and 15 contain PFGE standard strain G5244. PFGE pattern designations and sources of the strains are shown below each lane
See this image and copyright information in PMC

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