USDA, ARS Workshop

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USDA, ARS Workshop Poultry Food Assess Risk
Model (Poultry FARM)
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What is Poultry FARM?
A quantitative microbial risk assessment model
(QMRA) for Listeria, Salmonella, Campylobacter
and chicken meat.
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What does Poultry FARM do?
Predicts the public health impact of chicken meat
destined for specific distribution channels and
consumer populations
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What is the goal of Poultry FARM?
Packaging
Unsafe
Cooking
Safe
Distribution Channel
Consumption
To maximize the public health benefit of chicken
by ensuring its safety consumption
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What is QMRA?

• Hazard Identification
• Exposure Assessment
• Hazard Characterization
• Risk Characterization

Holistic
How many people will get sick and die?
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Hazard Identification
Initial distribution of pathogens among servings
Campylobacter (Cj)
Salmonella (Se)
Listeria (Lm)
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Pathogen levels on chicken meat(mean log
MPN/carcass)
Plant A Plant B Plant C Plant D Plant E
Lm 0 0 1.01 0.90 0
Se 0.11 0.17 0.74 0.19 0.48
Cj 3.65 2.37 3.86 4.19 3.45
Cj levels are higher than Lm and Se, which are
similar
Waldroup et al. (1992) J. Appl. Poultry Res.
1226-234.
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Simon Sez!!!
Relative differences among pathogens are
simulated in Poultry FARM
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Exposure Assessment
Plant Packaging Contamination
Distribution Abuse Growth/Death
Preparation Contamination Transfer
Cooling Abuse Growth/Death
Cooking Under-cooking Survival
Predicts how pathogen levels change from
farm-to-table
Serving Contamination Transfer
Table Consumption Dose-response
Key Unit Operation _ Human Action _ Pathogen
Event
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Physiological Differences
Se grows, whereas Cj dies at ambient temperatures
Burnette and Yoon (2004) Food Sci. Biotechnol.
13796-800
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Simon Sez!!!
Predictive models can be developed for each
pathogen event
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Hazard Characterization
No response
Infection
Mild illness
Illness
Determines whether or not an illness occurs
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Simon Sez!!!
Depends on the outcome of the interaction between
the pathogen, food and host
Disease Triangle
Pathogen
Host
Food
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Risk Characterization
Illness
Hospital
Death
Determines the severity of illness
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Simon Sez!!!
There are important differences in severity among
pathogens
Outcome Listeria Salmonella Campylobacter
Hospital 92.2 22.1 10.2
Death 20.0 0.78 0.1
Mead et al. (1999) http//www.cdc.gov/ncidod/eid/v
ol5no5/mead.htm
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Severity Assessment
Illness (C1)
Hospital (C2)
Death (C3)
Severity C1 2C2 10C3
Cases
Weight factor
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Simon Sez!!!
Foodborne illness is a random event
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Simon Sez!!!
Monte Carlo simulation is a good method for
modeling foodborne illness
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What is Monte Carlo Simulation?
A B C
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Simon Sez!!!
Foodborne illness is a rare event
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Rare Events' Modeling
Pathogen Number
Incidence
Extent
Discrete 1 0 0 0
Iteration 1 2 3 10,000
Pert (0,2,4) 1.8 1.2 0.2 2.2
Antilog 63.1 0 0 0
Round 63 0 0 0
IF(RiskDiscrete0,0,RiskPert)
Poultry FARM simulates pathogen-free servings
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Poultry FARM Tour
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Scenario Analysis
What IF?
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Which is higher risk?
Lot A
Lot B
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Scenario Settings
Input Pathogen A B C D E
Q1 Q2 Q3 Lm Se Cj 0.0 16.7 78.1 0.0 28.1 53.1 29.2 47.9 90.6 18.8 24.0 100.0 0.0 9.4 82.3
Waldroup et al (1992) J. Appl. Poultry Res.
1226-234.
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Scenario Settings
Question A B C D E
Q4 5 5 5 5 5
Q5 10 10 10 10 10
Q6 15 15 5 15 10
Q7 20 20 10 20 10
Q8 25 25 15 25 15
Q9 20 10 10 30 20
Q10 35 10 15 35 35
Q11 25 5 15 25 15
Q12 20 60 20 10 80
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Simulation Settings
QMRA Model Poultry FARM 3.0 Iterations 10,000
servings Simulations 100 Sampling Latin
Hypercube Random Number Generator Seed Random
Selection
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Simon Sez!!!
Each random number generator seed produces a
unique outcome of the scenario
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Listeria monocytogenes
A B C D E
Lm Se Cj 0 16.7 78.1 0 28.1 53.1 29.2 47.9 90.6 18.8 24 100 0 9.4 82.3
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Salmonella enterica
A B C D E
Lm Se Cj 0 16.7 78.1 0 28.1 53.1 29.2 47.9 90.6 18.8 24 100 0 9.4 82.3
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Campylobacter jejuni
A B C D E
Lm Se Cj 0 16.7 78.1 0 28.1 53.1 29.2 47.9 90.6 18.8 24 100 0 9.4 82.3
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Lm Se Cj
A B C D E
Lm Se Cj 0 16.7 78.1 0 28.1 53.1 29.2 47.9 90.6 18.8 24 100 0 9.4 82.3
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Simon Sez!!!
It is important to consider multiple pathogens
and post-process risk factors when assessing food
safety
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The End