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Foodborne Illness InvestigationSuccess Driven
by Collaboration

• Lisa Landry
• FWZID, PHAC
• Sept 21, 2006

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Foodborne Illness Investigation

• Responsibility for response to foodborne illness
• outbreaks is shared by
• Local and regional health authorities
• Provincial/territorial governments
• Federal officials

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CFIA - Foodborne Hazard

• Consumer complaints
• Food processing deviations
• Laboratory reports
• Notification from industry
• External information about a food safety problem

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PHAC - Human Illness

• Local/regional officials identify outbreak
• National or P/T surveillance activities identify
  an outbreak
• International outbreak with the potential to
  affect Canada

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Foodborne Illness Outbreak Response Protocol

• General principles and operating procedures for
  coordination and response
• Foodborne illness outbreaks with
  multi-jurisdictional implications
• Focus on information exchange and assistance
  between agencies
• Define roles and responsibilities

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FIORP Partners

• Local public health
• Provincial/territorial governments
• PHAC
• Health Canada
• CFIA

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Centre for Infectious Disease Prevention and
Control

• First point of contact for potential foodborne
  illness outbreaks
• Surveillance
• CNPHI Public Health Alerts
• Notification
• Networking with International groups
• Assistance/content expertise as requested

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Centre for Infectious Disease Prevention and
Control

• Respond to public health emergencies and
  infectious disease outbreaks
• More than one P/T or international
• Lead Outbreak Investigation Coordination
  Committee (OICC)
• Coordinate epidemiological investigation and
  information sharing
• Coordinate communications

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Current Information Exchange

• Weekly Food Safety and Zoonoses Teleconference
• NESP data
• Outbreak investigations
• Recalls
• Telephone/e-mail
• Public Health Alerts
• Teleconferences as necessary for outbreak
  response
• FIORP Outbreak Investigation Coordination
  Committee

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Foodborne Outbreak Scenarios

• Traditional scenario
• Cases clustered in time and space
• Common meal or event
• Often result of a food handling error

• New scenario
• Seemingly unlinked cases
• Widely distributed foods
• Food with long-shelf life or ready-to-eat,
  requiring no/little consumer handling

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Detecting an outbreak

• Traditional scenario
• Detected locally by
• Doctor
• Local public health
• Community
• Rely on syndromic surveillance and good
  relationships

• New scenario
• Detected by the lab
• Rare serotype
• Subtyping (phage typing, PFGE)
• Antimicrobial resistance
• Rely on lab-based surveillance and communication
  between lab and epi

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Steps in investigating an outbreak

• Determine existence of an outbreak
• Confirm diagnosis
• Assemble team
• Implement immediate control measures
• Develop case definition do case finding
• Analyse time, place, person data
• Generate hypothesis
• Test hypothesis
• Implement prevention control measures
• Disseminate findings, conduct evaluation

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SE PT30 outbreak

• An example of a collaborative foodborne
• illness outbreak investigation

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Outbreak Examples

• S. Heidelberg-nuggets
• Donairs
• E. coli ground beef
• Bean Sprouts

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Confirm existence of outbreak

• In Canada, in December 2000, the Ontario
  provincial lab identified an increase in the
  number of Salmonella isolates
• The isolates were serotyped the increase was
  seen specifically in S. Enteritidis (SE)
• 45 higher than in the 4 previous years

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The lab identifies an increase

• SE isolates were sent to the national lab for
  phage typing
• 16 (8/48) of isolates were phage type (PT) 30

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Assemble team

• Team included
• Local Public Health
• Provincial Public Health
• Provincial Laboratory
• National Microbiology Laboratory, PHAC
• CFIA
• Food Directorate, HC
• CIDPC, PHAC
• Some contact with CDC and FDA

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Implement rapid control measures

• Cases were scattered around the province
• No obvious links observed
• No immediate control measures were implemented

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SE PT30 case definition

• Confirmed case of SE PT30
• Since November 1, 2000, in Canada, any person
  with laboratory confirmation of infection by
  demonstration of SE PT30 in stool through culture
  and phage typing

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Find the cases

• The Ontario Ministry of Health communicated with
• Laboratories and doctors to increase their
  awareness and reporting of cases
• CIDPC,PHAC who notified other provinces and USA
• Case finding
• 60 cases reported in Ontario (Jan-Mar 01)
• Cases identified in 2 other provinces of Canada
  and in the USA

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Analyse the data

• Describe the data collected by
• Person
• Time
• Place
• To generate hypothesis about the potential source

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Onset dates of SE PT30 cases Canada, 2000-01
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Canada
USA
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Person, Place, Time - what are your data telling
you?

• Just women or just vegetarians
• Mostly children
• Specific ethnic culture
• Pet owners
• Periodicity to epidemic curve - weekends
• Travel season
• Only part of a town
• Only major centres or only small towns

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Generate hypothesis

• Identify trends and patterns
• From person, place and time data collected
• From visits and in-depth interviews with cases
• One or few investigators
• Questions change according to new information
  gathered
• If no idea, stop and rethink

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Generate hypothesis

• Recent cases were interviewed from January to
  March 2001 no source
• Hypothesis generation questionnaire was changed
  twice
• April 2001 one investigator interviewed 8 recent
  cases they had all eaten almonds in the 5 days
  prior to symptom onset HYPOTHESIS!

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Test the hypothesis

• Epidemiological study
• Case-control
• Cohort
• Cross-sectional
• Environmental investigation
• Traceback

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Test the hypothesis

• Case control study to test the hypothesis that
  almonds were the source of infection
• 15 recent cases
• 15 controls matched for neighborhood and age
• Asked about eating nuts and where they were
  purchased
• 13 cases had eaten raw almonds from the same
  chain of stores none of the controls had eaten
  almonds from these stores
• OR 13.0 (95CI 2.0 - 552.5)

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Canada
USA
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Source confirmation

• What type of almonds?
• Packaged or bulk, raw or processed etc.
• Where purchased from?
• Grocery store, restaurant etc
• What exactly should be recalled?
• Product identifiers
• What caused the problem?
• Examine process

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What is needed to trace a product

• Clear documentation of product name and
  production site
• Packaging if available
• Lot numbers, production time/date, best before
  date, size, point of purchase
• Invoices and shipping documents from receiver
  back to distributor back to producer back to farm

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Environmental investigations

• Not just an inspection!
• Requires a multi-disciplinary team epi, lab,
  inspection, agriculture, environment
• Not about what is normally done but what happened
  in a specific time in a specific place
• May involve multiple visits

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Towards Action

• PHAC works closely with CFIA
• Interpret epidemiology
• Product identified fits the epidemiology
• Have correctly confirmed a source
• PHAC continues working with CFIA to inform
  decision making

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TracebackEnvironmental investigation

• Almonds positive for SE PT30 from
• Home samples
• Stores and warehouse in Canada
• Processor in USA
• Almond farms in USA
• The source of farm contamination not identified

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Implement preventive measures

• Eliminate the source
• Immediately
• Recall product off the market
• Advise public not to eat the product
• Long-term
• Modify procedures in the cultivation, transport
  and processing of foods

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Implement preventive measures

• Recall of almonds by stores and processor
• Public advisories in Canada and US
• Improvement in lab methods for routine analysis
  of Salmonella in almonds
• Assessment of new methods for sterilization of
  raw almonds

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Onset dates of SE PT30 cases Canada, 2000-01
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A successful partnership

• PHAC works closely with our public health
• colleagues at all levels and CFIA to
• prevent and control foodborne illness