ARCHIVED - Canadian Integrated Surveillance Report: Salmonella, Campylobacter, verotoxigenic E. coli and Shigella, from 2000 to 2004

Background

This is the second Canadian Integrated Surveillance Report examining the reported trends for the top four enteric bacterial groups in Canada, based on data collected through various surveillance databases. This report focuses on the years 2000 to 2004. The surveillance data used to prepare this report were developed for different purposes and collect different data elements (see Appendix A for details). Each system has inherent limitations therefore, interpretation of data should be done with these limitations in mind (see Appendix A for more information).

In general, notification of an enteric disease case is initiated by the laboratory confirmation of a notifiable agent. There were 52 diseases identified as nationally notifiable during the 2000 to 2004 period⁽¹⁾. Among these, were 11 identified as enteric, food and waterborne diseases, including the four reviewed in this report (Appendix B). The local public health unit is informed of the case by the laboratory or physician, and through subsequent follow-up, acquires detailed information about the patient and potential risk factors. These data form the basis for reports in the National Notifiable Diseases databases - Summary [NDRS] and Individual Case [NNDI]. Local and regional laboratories forward some enteric pathogens to provincial laboratories for confirmation, identification and further subtyping. Aggregate reports of isolates are sent to the National Enteric Surveillance Program (NESP) by the provincial public health or central reference laboratory in each province. Some isolates from the provincial laboratories are sent to the Enteric Diseases Program, National Microbiology Laboratory (NML) for identification and additional subtyping. Isolates from non-human sources (food, animal and environment) are sent to the Laboratory for Foodborne Zoonoses (LFZ)for isolation and subtyping. As part of the Canadian Integrated Program for Antimicrobial Resistance surveillance (CIPARS), human Salmonella isolates are sent to NML, while Salmonella isolates from animal and food sources are sent to LFZ, for antimicrobial susceptibility testing. Additional data sources include the Hospital Morbidity Database (HMDB) from the Canadian Institute for Health Information (CIHI) which contains data about hospital admissions from across Canada, as well as data from the Death Database of the Vital Statistics program of Statistics Canada. This later database includes cause of death data (as reported on death certificates) on all deaths in Canada. Thus, each information source provides a unique perspective on enteric diseases in Canada.

This report uses all of these data sources to describe agents, cases and outbreaks related to the top four enteric bacterial groups reported in Canada: Salmonella, Campylobacter, verotoxigenic Escherichia coli and Shigella. While the main focus of this document is to describe disease trends over time and geographic area, comparisons between the main surveillance systems collecting similar data have also been highlighted, where appropriate. For instance, the rates of infection with Salmonella are quite similar whether reported as National Notifiable Diseases data or as laboratory-based data. For Campylobacter infections, however, the rates can be quite different depending on the data source and the province/territory. No single data source is adequate to describe all the various aspects of enteric disease in Canada. Consequently, the combined interpretation of each of the data sets in this document provides a comprehensive overview and highlights the most appropriate data source for answering particular questions about trends in enteric disease reporting in Canada.