FoodNet Canada Annual Report 2013

Executive Summary

FoodNet Canada tracks enteric diseases (illnesses of the gut) commonly known as food-poisoning, in Canadians, and traces them back to their sources, such as food, water and animals. These data are analyzed to help determine which sources are causing the most illness among Canadians and help us to track illnesses and their causes over time. 

In the 2013 surveillance year, FoodNet Canada was active in two areas: the Region of Waterloo Public Health in Ontario (ON) and the Fraser Health Authority of lower mainland British Columbia (BC).  In each location, or “sentinel site”, enhanced human disease surveillance is performed in parallel with active surveillance of the possible sources that ill persons may have been exposed to, to determine if they contain specific bacteria, viruses and parasites that could cause illness in humans. 

The following key findings are based on the surveillance data from 2013 in the ON and BC sites:

• A total of 803 human cases of 11 bacterial, viral and parasitic diseases were reported within the ON and BC sites in 2013. The three most frequently reported diseases (campylobacteriosis, salmonellosis and giardiasis) accounted for 81% of the cases.  
• Campylobacteriosis remained the most commonly reported enteric disease in both sentinel sites, with Campylobacter jejuni being the most common species associated with human campylobacteriosis. The majority of raw chicken samples tested were also contaminated with Campylobacter jejuni.  Consumption of unpasteurized milk was identified as a possible exposure factor. As observed in previous years, retail chicken meat continues to be considered to be the most important vehicle of transmission for Campylobacter.  However, other sources such as beef and dairy cattle, and their products, in particular unpasteurized milk, are also likely important. 
• Distributions of patient age and gender among the human salmonellosis cases in 2013 were similar to those observed historically.  The most commonly reported serovars from human cases of salmonellosis were Enteritidis, Heidelberg and Typhimurium.  Phage type and pulsed-field gel electrophoresis (PFGE) pattern alignment continues to be observed among isolates from endemic human cases, retail chicken products, and broiler chicken manure for both Salmonella Heidelberg and Salmonella Enteritidis. The prevalence of Salmonella on ground chicken and broiler chicken manure continues to be high as reported in previous years.  The most important possible vehicle of transmission identified were retail chicken products, especially uncooked chicken nuggets.
• Verotoxigenic E. coli (O157:H7 and non-O157:H7 serotypes) infections continue to be primarily domestically acquired, as demonstrated by the low number of travel-related cases in 2013.  E. coli O157:H7 PFGE patterns in both human and non-human samples from 2013 continued to show considerable diversity and a lack of persistence over time, as observed nationally and within the FoodNet Canada sites.
• As in previous years, pathogenic strains of Listeria monocytogenes were detected in 2013 from samples of skinless chicken breasts, ground beef, ground chicken and uncooked chicken nuggets. The scientific literature suggests that abattoirs and meat processing environments rather than farm animals may be an important source of L. monocytogenes. FoodNet Canada retail data from past surveillance years indicate that pathogenic serotypes of L. monocytogenes have been present on raw chicken, beef, and pork meat sold at retail, as well as less commonly, in bagged leafy greens.   L. monocytogenes was also detected in 2013 on samples of bagged leafy greens.  FoodNet Canada is contributing towards the development of new typing methods for L. monocytogenes based on whole genome sequencing.
• Findings are consistent with previous years showing that the majority of Yersinia cases were domestically acquired. Among travel-related cases, the majority reported travel to Central or South America in 2013.  As in the past, the majority of Shigella infections were travel-related, with Central or South America also being the most frequently reported travel destination.
• Giardia, Cryptosporidium and Cyclospora were all detected, though infrequently, on retail leafy greens in 2013.  Additionally, Giardia and Cryptosporidium were more commonly found in untreated surface water and recreational water (beaches) in 2013.  
• FoodNet Canada surveillance found both pathogenic norovirus and rotavirus on leafy greens.  Historically, norovirus and rotavirus have been identified in many of the tested sources, including fresh produce, retail meats, and food animal manure.  However, the potential risk to consumers is unknown given the uncertain viability of these viruses.
• Travel outside of Canada continued to add to the burden of enteric disease observed in Canada in 2013, with 27% of the reported cases from both sites (combined) likely involving infections acquired abroad.  Safe travel practices continue to be important considerations among Canadians.
• The collection of information across all of FoodNet Canada surveillance components (human, retail, on-farm, and water) in an enhanced and standardized way, has allowed for the integration of these data leading to the identification of patterns in subtype distributions among human cases and potential exposure sources over time. Continued surveillance and addition of more sentinel sites will help in refining key findings and informing prevention and control measures for enteric diseases in Canada.

For more details on the report and its key findings, please email: phac.foodnet.canada.aspc@canada.ca