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USDA, ARS Workshop Poultry Food Assess Risk Model (Poultry FARM). What is Poultry FARM?. A quantitative microbial risk assessment model (QMRA) for Listeria, Salmonella, Campylobacter and chicken meat. What does Poultry FARM do?.
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USDA, ARS Workshop Poultry Food Assess Risk Model (Poultry FARM)
What is Poultry FARM? A quantitative microbial risk assessment model (QMRA) for Listeria, Salmonella, Campylobacterand chicken meat.
What does Poultry FARM do? Predicts the public health impact of chicken meat destined for specific distribution channels and consumer populations
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
What is QMRA? • Hazard Identification • Exposure Assessment • Hazard Characterization • Risk Characterization Holistic How many people will get sick and die?
Hazard Identification Initial distribution of pathogens among servings Campylobacter (Cj) Listeria (Lm) Salmonella (Se)
Pathogen levels on chicken meat(mean log MPN/carcass) Cj levels are higher than Lm and Se, which are similar Waldroup et al. (1992) J. Appl. Poultry Res. 1:226-234.
Simon Sez!!! Relative differences among pathogens are simulated in Poultry FARM
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
Physiological Differences Se grows, whereas Cj dies at ambient temperatures Burnette and Yoon (2004) Food Sci. Biotechnol. 13:796-800
Simon Sez!!! Predictive models can be developed for each pathogen event
Hazard Characterization No response Infection Mild illness Illness Determines whether or not an illness occurs
Simon Sez!!! Depends on the outcome of the interaction between the pathogen, food and host Disease Triangle Pathogen Host Food
Risk Characterization Illness Hospital Death Determines the severity of illness
Simon Sez!!! There are important differences in severity among pathogens Mead et al. (1999) http://www.cdc.gov/ncidod/eid/vol5no5/mead.htm
Severity Assessment Illness (C1) Hospital (C2) Death (C3) Severity = C1 + 2C2 + 10C3 Cases Weight factor
Simon Sez!!! Foodborne illness is a random event
Simon Sez!!! Monte Carlo simulation is a good method for modeling foodborne illness
What is Monte Carlo Simulation? A + B = C
Simon Sez!!! Foodborne illness is a rare event
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(RiskDiscrete=0,0,RiskPert) Poultry FARM simulates pathogen-free servings
Scenario Analysis What IF?
Which is higher risk? Lot A Lot B
Scenario Settings Waldroup et al (1992) J. Appl. Poultry Res. 1:226-234.
Simulation Settings QMRA Model = Poultry FARM 3.0 Iterations = 10,000 servings Simulations = 100 Sampling = Latin Hypercube Random Number Generator Seed = Random Selection
Simon Sez!!! Each random number generator seed produces a unique outcome of the scenario
Simon Sez!!! It is important to consider multiple pathogens and post-process risk factors when assessing food safety