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USDA, ARS Workshop Poultry Food Assess Risk Model (Poultry FARM)
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A quantitative microbial risk assessment model (QMRA) for Listeria, Salmonella, Campylobacter and chicken meat.
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Predicts the public health impact of chicken meat destined for specific distribution channels and consumer populations
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Packaging Consumption Distribution Channel Cooking Safe Unsafe To maximize the public health benefit of chicken by ensuring its safety & consumption
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Hazard Identification Exposure Assessment Hazard Characterization Risk Characterization How many people will get sick and die? Holistic
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Salmonella (Se) Campylobacter (Cj) Initial distribution of pathogens among servings Listeria (Lm)
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Pathogen levels on chicken meat (mean log MPN/carcass) Plant APlant BPlant CPlant DPlant E Lm001.010.900 Se0.110.170.740.190.48 Cj3.652.373.864.193.45 Waldroup et al. (1992) J. Appl. Poultry Res. 1:226-234. Cj levels are higher than Lm and Se, which are similar
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Relative differences among pathogens are simulated in Poultry FARM
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Plant Packaging Contamination Distribution Abuse Growth/Death Preparation Contamination Transfer Cooling Abuse Growth/Death Cooking Under-cooking Survival Serving Contamination Transfer Table Consumption Dose-response Predicts how pathogen levels change from farm-to-table 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. 13:796-800
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Predictive models can be developed for each pathogen event
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No response InfectionMild illness Illness Determines whether or not an illness occurs
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Depends on the outcome of the interaction between the pathogen, food and host Disease Triangle PathogenHost Food
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IllnessHospitalDeath Determines the severity of illness
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There are important differences in severity among pathogens OutcomeListeriaSalmonellaCampylobacter Hospital92.2%22.1%10.2% Death20.0%0.78%0.1% Mead et al. (1999) http://www.cdc.gov/ncidod/eid/vol5no5/mead.htm
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Illness (C 1 ) Hospital (C 2 ) Death (C 3 ) Severity = C 1 + 2C 2 + 10C 3 Weight factor Cases
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Foodborne illness is a random event
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Monte Carlo simulation is a good method for modeling foodborne illness
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A + B = C
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Foodborne illness is a rare event
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Iteration 1 2 3 : 10,000 Discrete 1 0 : 0 Pert (0,2,4) 1.8 1.2 0.2 : 2.2 Antilog 63.1 0 : 0 Round 63 0 : 0 IncidenceExtent Pathogen Number =IF(RiskDiscrete=0,0,RiskPert) Poultry FARM simulates pathogen-free servings
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Poultry FARM Tour
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Lot ALot B Which is higher risk?
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InputPathogenABCDE 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. 1:226-234.
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QuestionABCDE Q45% Q510% Q615% 5%15%10% Q720% 10%20%10% Q825% 15%25%15% Q920%10% 30%20% Q1035%10%15%35% Q1125%5%15%25%15% Q1220%60%20%10%80%
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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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Each random number generator seed produces a unique outcome of the scenario
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Listeria monocytogenesABCDELmSeCj0%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 entericaABCDELmSeCj0%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 jejuniABCDELmSeCj0%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 + CjABCDELmSeCj0%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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It is important to consider multiple pathogens and post-process risk factors when assessing food safety
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