Synthesis Foodborne Outbreaks

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Synthesis Foodborne Outbreaks

• EPIET Introductory Course, 2006Lazareto, Menorca

Prepared by Mike Catchpole
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Steps of an outbreak investigation

• Confirm outbreak and diagnosis
• Form Outbreak Control Team
• Define a case
• Identify cases and obtain information
• Describe data by time, place, person
• Develop hypothesis
• Test hypothesis analytical studies
• Additional studies
• Communicate results
• outbreak report, publication
• Implement control measures

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Epidemiological findings

• Descriptive data
• Who was affected, when and where
• Analytical studies
• May demonstrate statistically significant
  association between illness and particular
  demographic or exposure variables

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But...

• Why?
• How?
• Where from?
• How can we stop it happening (again)?

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Foodborne outbreaks most common causes in UK

• Preparation of food too far in advance of needs
• Storage of food at room temperature
• Inadequate cooling
• Inadequate reheating
• Use of contaminated processed food
• Undercooking
• Cross contamination from raw to cooked food
• Consumption of raw food
• Infected food handlers

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Routes of Food Contamination

• Contamination of raw food or failure to eliminate
  acceptable contamination of raw food
• Farming practice/abattoir practice/zoonotic
  problems
• Pasteurisation failure
• Undercooking, inadequate cooling
• Contamination during food preparation
• Infected food handler
• Environmental contamination
• Cross contamination (from raw or processed
  ingredients)
• Contamination after food preparation
• Infected food handler
• Inadequate storage, cooling or reheating
• Environmental contamination
• Cross contamination from raw food

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Identifying the cause of food contamination

• Inspection and microbiological examination of
  food preparation premises
• Questioning about food preparation staff health
• Observation and questioning about food
  preparation practices (storage of raw/cooked
  foods)
• Scrutiny of records (staff sickness,
  fridge/freezer temperature charts, oven
  temperature charts, cleaning records) and
  checking of calibration of instruments

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Identifying the cause of food contamination

• Inspection and microbiological examination of
  farms
• Scrutiny of records (pasteurisation temperature
  charts, veterinary records, staff sickness
  records) and checking of calibration of
  instruments
• Observation and questioning about animal
  husbandry and crop management

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Identifying the cause of food contamination

• Inspection and microbiological examination of
  commercial food preparation premises and track
  back of food distribution chains
• Scrutiny of records (temperature charts, quality
  control records, staff sickness records) and
  checking of calibration of instruments
• HACCP (hazard analysis of critical control
  points) and inspection of production line
• Inspection of supplier records

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Why investigate outbreaks?

• Stop the outbreak
• Understand what happened and why
• Prevent future outbreaks
• Improve our knowledge
• Improve surveillance and outbreak detection
• Training