State three measures for preventing foodborne illnesses

Chapter 11 Discussion

Learning Objectives
By the end of this chapter, the reader will be able to:
State three measures for preventing foodborne illnesses
Discuss 10 microbiological agents that are implicated in foodborne illness
Explain the significance of foodborne illness for the world’s population
List five categories of contaminants in the food supply
Describe one major regulation for protecting the safety of food from carcinogens

Foodborne Diseases/Infections
“illnesses acquired by consumption of contaminated food; they are frequently and inaccurately referred to as food poisoning”
An outbreak indicates “the occurrence of a similar illness among two or more people which an investigation linked to consumption of a common meal or food items, except for botulism (one case is an outbreak)”

Burden of Illness Pyramid

Risk Factors for Foodborne Illness – USA
63% Inadequate cooling and cold holding temperatures
29% Preparing food ahead of planned event
27% Inadequate hot holding temperatures
26% Poor personal hygiene/infected persons
25% Inadequate reheating
9% Inadequate cleaning of equipment
7% Use of leftovers
6% Cross-contamination
5% Inadequate cooking or heating process
… List goes on…

Risk Factors for Foodborne Illness
So what are some of the prevention measures we can take?
Clean, separate, cook, & chill
Hand hygiene
Irradiation of food (common for meats)

Risk Factors for Foodborne Illness

Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over

Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over
First step of process
Generally through public health surveillance (usually passive)
Nationally Notifiable Conditions
Establish a normal baseline incidence of a given disease
Detect an increase in the incidence, or a “cluster”
If the cluster has something in common, then it is considered an outbreak

Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over
Usually the first cases identified are only a small part of the total outbreak
Develop a “case definition”, including:
Pathogen & symptoms
Time range & geographic area
Other criteria (common source or DNA/PFGE fingerprint)
May distinguish probable vs. confirmed
Using the case definition, active surveillance for additional cases
Surveying individuals
Looking through health records/laboratory reports
Reaching out to other health officials

Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over
Developing possible sources of illness, modes of transmission, and even a specific source
Iterative process, where hypotheses are continually refined or refuted
When lots of potential exposures, conduct “hypothesis-generating interviews” to determine common exposures (e.g. food items consumed)
Challenging due to memory and amount of items consumed

Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over
Once hypotheses are generated, need to test them to see if correct source was identified
Case-control studies are the most common type of tests
Controls may be matched on geography and time
Determine if eating a particular item was statistically more common for cases
What test is used to help determine?

Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over
Based upon the tests, may be able to assess the point of contamination
Could trace as far back as the agriculture production of the food
If the common source was prepared in several kitchens, by several people, would suggest an upstream point of contamination
Can conduct environmental assessments, looking for related pathogen

Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over
Once a point of contamination is identified, control measures should be implemented immediately
Could include…
Clean/disinfect facilities
Temporarily close restaurant/plant
Recalling food items
Educate the public
Dispose of particular items

Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over
An outbreak ends when the number of new illnesses drops back to the normal baseline (remember Step 1)
Continue to conduct surveillance in case new cases arise
In which case, the investigation would be reopened and hypotheses may need to be revised or retested

PulseNet – Identifying Outbreaks
National laboratory network of 83 public health laboratories
Uses “fingerprinting” of microorganisms – either by DNA or patterns of bacteria
Pulse-field gel electrophoresis (PFGE)
Whole genome sequencing (WGS)
Used for several foodborne illnesses – E. coli, Salmonella, Shigella, Vibrio cholera, and more…

Blue Bell & Listeria
February 2015 – South Carolina Department of Health and Environmental Control found listeria as part of routine sampling of products
Based on this, Texas Department of State Health Services collected product samples from the Blue Bell Creameries facility in Brenham, Texas – found the bacteria in the same products identified in South Carolina
March 2015 – Kansas health officials identified the same PFGE pattern in two cases
These two cases and four other cases developed in the hospital, after patients ate the products containing listeria
March 13, 2015 – Blue Bell removed and recalled the product in question and shut down the production line in the Brenham, Texas facility
April 2015 – PulseNet database identified 6 more cases across 3 states with the same PFGE pattern
Linked these cases to the Blue Bell Oklahoma facility
April 20, 2015 – Blue Bell recalls ALL of its products from all of its facilities

Blue Bell & Listeria

Shiga Toxin-producing E. Coli

Shiga Toxin-producing Escherichia coli (STEC)
Common strains are O157:H7 and O104:H4
Shiga Toxin – halts protein synthesis within target cells by targeting the ribosomes
Similar to mechanism of ricin

2015 Chipotle Outbreak – E. Coli O26 (STEC)
Non-pathogenic strains are part of the normal flora in animals and humans
Symptoms (~8 days):
Abdominal pain
Diarrhea (watery and/or bloody)
No or low-grade fever
Sources:
Undercooked meat
Has also been associated with alfalfa, fruit juices, salami, lettuce, cheese, game meat, and raw milk

2015 Chipotle Outbreak – E. Coli O26 (STEC)
Outbreak in Washington and Oregon in late 2015
Most likely associated with one food item (but never identified)
October 31, 2015 – WA & OR officials announce an outbreak linked to Chipotle food
November 3, 2015 – Chipotle closes 43 restaurants in WA & OR
November 20, 2015 – The CDC expands the scope to six states, affected at least 45 people
December 4, 2015 – The CDC again expands the scope to 9 states and 52 people
Finally, outbreak was expanded to 11 states and 55 people

2015 Chipotle Outbreak – E. Coli O26 (STEC)
Outbreak in Washington and Oregon in late 2015
Most likely associated with one food item (but never identified)
October 31, 2015 – WA & OR officials announce an outbreak linked to Chipotle food
November 3, 2015 – Chipotle closes 43 restaurants in WA & OR
November 20, 2015 – The CDC expands the scope to six states, affected at least 45 people
December 4, 2015 – The CDC again expands the scope to 9 states and 52 people
Finally, outbreak was expanded to 11 states and 55 people

2015 Chipotle Outbreak – E. Coli O26 (STEC)
Whole genome sequencing was conducted on 36 of the STEC O26 isolates (from the 55 individuals identified)
All 36 isolates were closely related genetically
Provided additional evidence that the illnesses were linked to a common source

2015 Chipotle Outbreak – E. Coli O26 (STEC)
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