PulseNet is a national laboratory-based surveillance system for identifying outbreaks of foodborne illnesses. Learn how PulseNet Canada uses genomic science to detect outbreaks across Canada.
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Purpose of PulseNet Canada
PulseNet Canada is a national surveillance system for identifying and responding to foodborne disease outbreaks. It is comprised of a network of public health laboratories across Canada linked by databases. The PulseNet Canada team at the National Microbiology Laboratory (NML) in Winnipeg, Manitoba, houses and manages the national databases. This national network tracks all cases of foodborne illnesses caused by:
- Vibrio
- E. coli
- Shigella
- Salmonella
- Listeria monocytogenes
PulseNet Canada uses advanced genomic science to detect outbreaks that may have cases occurring anywhere in Canada.
Foodborne illnesses are a global problem. Outbreaks can be widespread and often span wide geographic regions, including across international borders due to the trade of raw and processed food and international travel.
Whole genome sequencing databases
A critical component of detecting and investigating human foodborne outbreaks is the DNA "fingerprinting" of the bacteria that cause the outbreaks. These fingerprints are the DNA profiles obtained by whole genome sequencing. When organisms have the same DNA sequence that is a clue that the illnesses may have come from the same source.
PulseNet Canada scientists generate whole genome sequences for each case of disease soon after it is diagnosed, and the sequences are entered into NML's electronic database.
This database houses all of the sequences from all cases of foodborne illnesses in Canada so public health officials can quickly identify an outbreak strain. These profiles are available on-line to partners. Using whole genome sequencing technology and a centralized national database permits rapid inter-laboratory comparison and communication of information about foodborne illnesses, and flags potential outbreaks as soon as possible.
Using this system helps:
- identify whether an outbreak is occurring even if the affected people are geographically far apart
- trigger the need to investigate and intervene quickly to protect the public
- determine when an outbreak is over
PulseNet Canada also provides a mechanism for laboratories and investigators to communicate clearly and quickly across the country.
Monitoring process
The monitoring process for foodborne illness outbreaks follows a series of steps:
- Provincial public laboratories isolate enteric bacterial pathogens from human clinical cases.
- Participating laboratories perform whole genome sequencing using standardized methods, equipment and software.
- PulseNet scientists enter whole genome sequences into electronic databases at the provincial laboratories and the NML. Participating members have a direct link to the national databases.
- Participating laboratories post clusters of cases with matching whole genome sequencing profiles in their jurisdictions to the PulseNet Canada discussion board on the Canadian Network for Public Health Intelligence. Members view and respond to postings on a daily basis.
- Database managers at NML search for clusters of related isolates in more than 1 province. They report the results to the participating lab(s) and Public Health Agency of Canada epidemiologists, and post them to the discussion board.
PulseNet Canada partners
Provinces and select federal departments work together to operate PulseNet Canada in tracking foodborne pathogens across the country. Participating laboratories include:
History of PulseNet
The Centers for Disease Control and Prevention (CDC), along with the Association of Public Health Laboratories, developed PulseNet in the United States in response to a large outbreak of E. coli in 1996. During that outbreak, scientists at the CDC (Atlanta, Georgia) performed DNA "fingerprinting" by pulsed-field gel electrophoresis (PFGE). They determined that the strain of E. coli found in patients had the same PFGE pattern as the strain found in hamburger patties served at a large chain of regional fast food restaurants. From this discovery, they built a national network to perform PFGE routinely and share the data across the United States for rapid outbreak detection and response.
We, along with our provincial public health laboratory partners, established PulseNet Canada in 2001 to harmonize our surveillance system with PulseNet USA. Shortly thereafter, PulseNet International was formed, bringing harmonized foodborne outbreak detection and response across the world. As of 2021, 88 countries participate in PulseNet International.
Beginning in 2013, a newer, better technology was emerging (whole genome sequencing), and PulseNet Canada began planning to replace PFGE with whole genome sequencing. Compared to the old technology, whole genome sequencing is a much more accurate method of tracking illnesses. In 2017, PFGE was replaced by whole genome sequencing. Today, whole genome sequencing provides the most accurate bacterial fingerprinting data possible.
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