achieving continuous improvement in reductions in

Achieving ContinuousImprovement in Reductionsin Foodborne Listeriosis: A

Risk-Based Approach

Overview of Expert Panel Report

Michael Doyle

Objective: Develop a strategy to achievecontinuous improvement in reducing thenumber of cases of foodborne listeriosis inthe USA

_ Not attempting to eradicate foodborne listeriosis

ApproachOrganize an Expert Panel through the

International Life Sciences Institute-RiskScience Institute

_ Publish a report of experts' opinions based onscientific information presently available

Approach: Develop a road map

_ Identify landmarks

_ Identify routes to our goal

Landmarks for Reducing Incidence ofFoodborne Listeriosis

1. Identify Baseline

_ 2002 FoodNet surveillance data

_ 0.27 cases of listeriosis per 100,000 USpopulation

_ Represents culture-confirmed cases only;actual incidence of listeriosis is greater

_ Serves as a standardized data collection andreporting system to enable monitoring trendsin incidence of listeriosis


2. Define "At-Risk" Populations

a. Exquisitely sensitive (highly immunocompromised)

_ Very high risk of listeriosis

_ Transplant patients and individuals on cancertherapy

b. An increased risk (immunocompromised)

_ Higher risk of listeriosis than normal healthypopulation but less sensitive than exquisitelysensitive

_ Includes elderly and pregnant women


2. Define "At-Risk" Populations (Cont.)

c. Very low risk

_ Normal healthy population

d. Unique "high risk" subpopulations

_ Pregnant Latina women (likely associatedwith consumption of queso blanco/fresco softcheese)


2. Define "At-Risk" Populations (Cont.)

_ Need different control strategies for different "atrisk" populations

_ Need to know number of listeriosis cases in eachcategory to assess impact of control strategies onoverall incidence of listeriosis


3. Define "High Risk" Foods

_ Certain foods pose a substantially greater risk ofacquiring listeriosis

_ Based on outbreak and sporadic case (case-control) studies, and on risk assessment

Predicted Cases of Listeriosis per Serving -Total Population (HHS/USDA 2003,

www.foodsafety.gov)

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3. Define "High Risk" Foods (Cont.)

_ Characteristics of high risk foods

a. Have potential for contamination with L.monocytogenes

b. Support growth of L. monocytogenes (to highnumbers)

c. Are ready to eat

d. Require refrigeration

e. Are stored for an extended period of time


3. Define "High Risk" Foods (Cont.)

_ Two critical components requiring expert opinion

a. How long is an extended period of time?

b. What is the cell number to which L.monocytogenes must grow for a food to beconsidered "high risk"?

_ Risk of listeriosis increases as the numberof listeriae in a food increases


4. Additional Considerations

_ Dose-response data useful for estimating theimpact of reducing the numbers of L.monocytogenes in foods

_ Example

If the risk of illness associated withconsuming 106 listeriae per serving is 1 in1,000,000, then reducing the number oflisteriae to 104 or 102 per serving will reducethe risk by several orders of magnitude


4. Additional Considerations (Cont.)

_ Information regarding virulence attributes of L.monocytogenes strains useful for identifyinghigher risk foods

_ Some strains are more virulent than others, butdo not have sufficient knowledge to differentiatethese strains based on genetic or phenotypicmarkers


Virulence attributes of L. monocytogenes strains(Cont.)

_ Present information, based on outbreak anddose-response data, indicate that exceptionallyvirulent (low infectious dose) strains (like E. coliO157:H7) of L. monocytogenes have causedfew to no identified illnesses in Category 2(Intermediate sensitivity) or Category 3 (Normalhealth) "At-Risk" populations


Virulence attributes of L. monocytogenes strains(Cont.)

_ Hence, for purposes of having a major impact onreducing the incidence of foodborne listeriosis,consider outbreak-associated L. monocytogenesserotype 4b strain involving Hispanic-style softcheese and pregnant woman to be "typical"virulent strain

Control Strategies to ProvideContinuous Improvement in Reduction

of Foodborne Listeriosis in the USA(Routes to Our Goal)

_ Major impact will involve :

_ Reducing the number of servings of "high-risk"foods

_ Prevent contamination

_ Prevent growth in "high risk" foods

_ Educating "at-risk" populations

Control Strategies_ Focus on Controlling/Eliminating L. monocytogenes in

"High-Risk" Foods to reduce the number of serving ofhigh-risk foods

_ Most effective strategies include:

_ Reformulating foods to include antimicrobials toprevent/retard growth of listeriae to high numbers

_ Post-packaging treatments that destroy listeriaeon product

_ Example, hot water treatment of packaged delimeats

_ Weakness-recontamination of high-riskfoods in home

Control Strategies

_ Controlling L. monocytogenes in "High-Risk" Foods(Cont.)

_ Most effective strategies:

_ Establishing acceptable storage times of foods thatsupport growth of listeriae to high numbers

Control Strategies

Educate "At-Risk" PopulationsPrinciples and Philosophy

_ Human behavior is a factor in the continuedincidence of listeriosis

_ All food handlers and end-users need educationand training to ensure product safety

_ To be most effective, educational messages shouldbe tailored to the individuals who will be expected toimplement the guidance

Control Strategies

_ Educate "At-Risk" Populations

_ Need to be targeted messages to differentpopulations at risk

_ Category 1 - Exquisitely sensitive

_ No safe level of L. monocytogenes;individuals should be maintained onrestricted low microbial diets

Control Strategies

_ Need to be targeted messages to differentpopulations at risk

_ Category 2 - At increased risk

_ Guidance on healthy eating, including avoidhigh-risk foods or cook them beforeconsumption

_ Category 3 - Very low risk

_ Typical safe food handling practices

Risk-based Approach

_ Focus resources on reducing levels of L.monocytogenes in high risk foods

_ Target education messages to at-risk consumers

Caveats

_ Report is still a work in progress

_ As with most works involving scientific judgments onreduction of risks associated with public health, thereare a diversity of opinions

_ Do not have complete consensus on all details, butend product will represent the expert opinion of thevast majority of our committee

Expert Panel Members

_ David Acheson, FDA/CFSAN

_ Phillip Bird, Hunter Public Health Unit, NSW Australia

_ Bob Buchanan, FDA/CFSAN

_ Victor Cook, USDA/FSIS

_ Catherine Donnelly, University of Vermont

_ Mike Doyle, CFS, University of Georgia (Chair)

_ Jeff Farber, Health Canada

_ Sara Fein, FDA/CFSAN

_ Alicia Fry, CDC

Expert Panel Members, Cont'd

_ Lone Gram, Danish Institute for Fisheries Research

_ Christopher Griffith, University of Wales

_ Paul Hall, Kraft Foods

_ Anthony Hepton, Dole Foods (retired)

_ Dr. Walt Hill, USDA/FSIS

_ Val Hillers, Washington State University

_ Janell Kause, USDA/FSIS

_ Pat Kendall, Colorado State University

_ Lydia Kleiner, USDA/FSIS


_ Carol Maczka, USDA/FSIS

_ Lydia Medeiros, Ohio State University

_ Bob Mitchell, Health Protection Agency, UK

_ Ranzell (Nick) Nickelson, Standard Meat

_ Catherine Nnoka, ILSI North America

_ Barbara O'Brien, USDA/FSIS

_ Kathleen O'Donnell, Wegman's Food Markets

_ Rich Raybourne, FDA/CFSAN

_ Jose Alberto Rangel Cordero, Dept of Health, Mexico


_ Mary Alice Smith, University of Georgia

_ Julia Smith, CDC

_ William H. Sperber, Cargill

_ Katherine Swanson, General Mills

_ Ewen Todd, Michigan State University

_ Isabel Walls, ILSI Risk Science Institute

_ Martin Wiedmann, Cornell University

_ Dick Whiting, FDA/CFSAN

_ Don Zink, FDA/CFSAN

Peer Reviewers

_ John Cerveny, Oscar Meyer (retired)

_ Margaret Hardin, Smithfield Packing Company

_ Jill Hollingsworth, Food Marketing Institute

_ Randall Huffman, American Meat Institute

_ Hannu Korkeala, University of Helsinki

_ Jim McLauchlin, Health Protection Agency, UK

_ Art Miller, FDA/CFSAN

_ Greg Paoli, Decisionalysis, Canada

_ Walter F. Schlech, Dalhousie University

_ Marcel Zwietering, Wageningen University

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