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Where Must Food Safety Begin?. Solutions are complex but must begin at the farm Food producers must consider and treat their products as foods rather than as commodities. Food Producers Examples of promising CP’s for preharvest foods -Probiotics and competitive exclusion bacteria

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Where Must Food Safety Begin?

  • Solutions are complex but must begin at the farm

  • Food producers must consider and treat their products as foods rather than as commodities


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Food Producers

Examples of promising CP’s for preharvest foods

-Probiotics and competitive exclusion bacteria

Use of beneficial microorganisms that prevent colonization or eliminate pathogens from animals used for food products

-Bacteriophage

-Innovative vaccines

-Dietary and feeding practices

Intervention or Control Points


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Primary Food Processors

Produce (fresh-cut)

Meat (slaughter)

Poultry (slaughter)

Intervention or Control Points


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Fresh-cut Produce Processing

Have moved early stages of processing lettuce to the field

Lettuce heads are cut at stem and exterior leaves and core are removed

Core area and exterior of head are treated with 5 to 200 ppm chlorinated water

Lettuce is loaded by conveyor belt into plastic bag-lined bins and cooled down within 2 hr

Rain (mud) and wind increase contamination potential

Some processors are shredding lettuce in field

Intervention or Control Points?


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ProduceTreatmentalog Salmonella/g(% Reduction)

ShreddedControl3.31( 0)

lettuce120 ppm chlorine 2.53(83)

200 ppm chlorine 2.49(85)

DicedControl3.00( 0)

tomatoes120 ppm chlorine 2.73(45)

200 ppm chlorine 2.69(51)

aSubmerged and agitated for 40 sec at 4oC

W. R. Weissinger et al. Int. J. Food Microbiol. 62:123 (2000)

Effect of chlorinated water on Salmonella on shredded lettuce and diced tomatoes


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Beef Slaughter

Steam vacuuming of fecal contamination

Effective in reducing bacterial load but not all fecal contamination is visible

Steam pasteurization

Reduce pathogens by 10- to 100-fold

Organic acid rinses

Reducing pathogens by 10- to 100-fold

Intervention or Control Points


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Poultry Slaughter

Increased use of water rinses

Increased chlorine in chill water tanks

Chlorine dioxide in chill water tanks

End product contamination of poultry averages ca. 9% Salmonella and 60+% Campylobacter

Intervention or Control Points


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Food Processors

Innovative technologies other than heat treatment for killing/controlling pathogens

(Examples)

High hydrostatic pressure

High intensity light

Pulsed electric fields

Antimicrobial chemicals/gases (ozone, chlorine dioxide)

Hurdles (water activity, pH)

Irradiation

Intervention or Control Points


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Food Processors

No magic bullet for all foods

Most innovative technologies have limitations

Produce off-odors and off-flavors in high fat foods

Not penetrating to kill microorganisms within food

Not capable in killing large populations of pathogens when used at maximum practical levels

Production of undesirable products in waste streams

Reduction in foods of beneficial bacteria needed to prevent infections by pathogens

Intervention or Control Points


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Gamma Irradiation

Not a panacea to eliminate pathogens from all foods

Emerging Issues in the Microbiological Safety of Foods


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Gamma Irradiation of Ground Beef

  • D-values of pathogens in ground beef (8-14% and 27-28% fat) subjected to 60Co Gamma irradiation


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Food Irradiation

  • 5 log10 inactivation of Salmonella in ground beef requires 3.3 kGy at 3-5ºC and 4.0 kGy at –17o to –15ºC

  • Sensory characteristics of irradiated (3 kGy) food:

    • Ground beef (>10%) Undesirable off- odor/flavor

    • White chicken meat Acceptable

    • Lettuce Undesirable texture


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Has End-Product Testing of Ground Beef at Retail and Processing Facilities and

Associated Recalls or Withholding of Ground Beef from Market Reduced E. coli O157:H7 Infections in Humans?


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Number of Confirmed E. coli O157:H7-Positive Ground Beef Samples by USDA-FSIS

Year

No. Positive/No. Samples

0/891

CY 1994a

3/5,407

CY 1995

CY 1996

4/5,703

CY 1997b

4/6,065

14/8,080

CY 1998

32/7,786

CY 1999c

CY 2000

55/6,374

CY 2001 (through 10/4)

47/>5,400


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Sites of Sampling for E. coli O157:H7 Ground Beef Testing

Location of Sampling

Imports

Federal Plants

Retail Stores

State Plants

Year

(No. of Samples Analyzed)

CY 1994

293

588

10

0

CY 1995

2521 (2)

2787 (1)

29

70

CY 1996

1459 (1)

44

228

3972 (3)

CY 1997

1120 (2)

4849 (1)

8

88 (1)

CY 1998

4281 (12)

3731 (2)

55

13

CY 1999

4515 (21)

3212 (11)

43

16

CY 2000

5019 (36)

1292 (17)

50 (1)

13 (1)


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Recalls of Ground Beef for E. coli O157:H7 Contamination

Year

No. of Recalls

1996

1

1997

2

1998

7

1999

4

27

2000

2001 (through 10/12)

21

USDA-FSIS


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Incidence of E. coli O157:H7 Infections Based on FoodNeta

No. of Cases Per 100,000

Year

1996

2.7

1997

2.3

1998

2.8

1999

2.1

2000

2.9

a 5 original sites

Centers for Disease Control and Prevention

MMWR 50:241 (2001)


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How Effective Are Rules Implemented by Federal Agencies in Reducing E. coli O157

  • End product testing for E. coli O157 of ground beef began in 1994

  • More sensitive testing methods introduced in 1997 and 1999

  • Number of E. coli O157-positive samples resulting in ground beef withheld or recalled increased from 4 in 1996 to 32 in 1999 and 55 in 2000

  • Incidence of E. coli O157 infections per 100,000 population was 2.7 in 1996, 2.1 in 1999 and 2.9 in 2000


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Major Limitation of End Product Testing of Ground Beef at Retail

  • Much of product in market place will have been consumed by the time recall is initiated

    • Example: Hudson Foods recalled 25 million pounds of ground beef for E. coli O157 contamination; only 10 million pounds were recovered


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Outbreak Data Indicate Large-Scale E. coli O157:H7 Contamination of Ground Beef

  • Testing of Jack-in-the-Box E. coli O157:H7 outbreak revealed 6 of 17 lots produced during one day's production were contaminated with E. coli O157 [Tuttle et al., Epidemiol. Infect. 122:185 (1999)]

  • In contrast, repeat testing of ground beef from the same lots in which E. coli O157-positive ground beef was identified by the USDA's random sampling program are typically E. coli O157:H7-negative


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Could USDA's Approach of Random Testing of Ground Beef for E. coli O157:H7 Be Improved?

  • Placing more emphasis on large-scale and/or high level E. coli O157 contamination of lots at processing plant and less emphasis on low-level, highly sporadic contamination would likely be more effective in reducing ground beef-associated E. coli O157 infections in humans


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Need Strategic Approach to Identify Control Measures Having Greatest Public Health Impact

  • Identify intervention strategies (critical control points) within food continuum at which control measures will have the greatest influence on providing safe foods

    • Quantitative microbial risk assessment

      • Systematic collection of epidemiologic, exposure and dose-response data, and analysis of data

    • Case-control studies to identify risk factors of sporadic infections


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Quantitative Microbiological Risk Assessment

  • Hazard identification

  • Exposure assessment

  • Dose-response assessment

  • Risk characterization


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Types of Quantitative Microbial Risk Assessment

  • Risk ranking

    • Rank foods according to risk of acquiring illness

  • Product/pathogen pathway

    • Determine where in production of a food the greatest risks to human health would occur if not properly controlled or identify points where interventions would have greatest impact on reducing risk of illness


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Food Category Intermediate Age Elderly Perinatal

Seafood

Smoked 3 3 3

Raw141414

Preserved Fish 7 7 6

Cooked, RTE Crustaceans 6 5 5

Produce

Vegetables 171717

Fruit 181818

Relative Risk Rankings for Listeriosis Among Food Categories for Three Subpopulations (Per-Serving Basis)


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Food Category Intermediate Age Elderly Perinatal

Meats

Frankfurters

All Frankfurters 8 8 7

Only Reheated Franks [15] [15] [15]

Only Non-Reheated Franks [1] [2] [2]

Dry/Semi-dry Fermented Sausages 13 12 12

Deli Meats 44 4

Pt & Meat Spreads 12 2

Combination Foods

Deli Salads 5 6 8

Relative Risk Rankings for Listeriosis Among Food Categories for Three Subpopulations (Per-Serving Basis)


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Food CategoryIntermediate Age Elderly Perinatal

Dairy

Soft, Mold-Ripened & 9 9 9

Blue-Veined Cheese

Goat, Sheep & Feta Cheese 161616

Fresh Soft Cheese (quesco fresco) 2 1 1

Heat-Treated Natural/Process Cheese 151515

Aged Cheese 191919

Pasteurized Milk 101010

Unpasteurized Milk 111111

Ice Cream & Frozen Dairy Desserts 202020

Misc. Dairy Products 121313

Relative Risk Rankings for Listeriosis Among Food Categories for Three Subpopulations (Per-Serving Basis)


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Microbial Quantitative Risk Assessment

  • Identify those areas in the food continuum where intervention strategies will have the greatest impact on reducing the risk of foodborne illness

    • Example, E. coli O157:H7 infection from ground beef

      • Proper refrigeration (<45oF) will prevent pathogen from growing on beef carcasses/ pieces and limit level of contamination of ground beef


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Weakness of Microbial Quantitative Risk Assessments

  • Insufficient data available

    • Many MQRAs extrapolate data from studies that were not designed for the purpose for which the data are used in an MQRA

  • Need to design and conduct studies that specifically address data gaps of MQRAs


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Case-control studies can be valuable toolfor identifying principal risk factors contributing to human illnesses caused by specific pathogens


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Risk Factors Associated with Sporadic Cases of E. coli O157:H7 Infection in U.S.

1. Eating undercooked ground beef

2. Handling animals on farms (especially cattle)

U.S. Centers for Disease Control and Prevention, 1998


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Risk Factors Associated with E. coli O157:H7 Infections in Scotland

1. Handling / preparing raw food (40%)

2. Involved in gardening / garden play (36%)

3. Lived on / visited farm (20%)

4. Direct / indirect contact with animal manure (17%)

5. Private water supplies (12%)

6. Recent failures with high coliform counts of water supplies (12%)

J. E. Coda et al., J. Infect. 36:317, 1998


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Present Understanding of E. coli O157:H7

  • Cattle are principal host/carrier

  • Visiting a farm and eating undercooked ground beef (exposure to cattle manure) are primary risk factors for infection

  • Contaminated cattle manure likely source of many human infections

    • Handling animals on farm (dogs, cattle)

    • Well water; lakes

    • Seeds used for sprouts

    • Produce fertilized with manure

    • Undercooked ground beef

    • Unpasteurized milk; cheese made from contaminated milk

    • Handling manure-encrusted potatoes

    • Fermented beef sausage

  • Estimated 1.23 billion tons of cattle manure produced annually in U.S.


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Missed Opportunity?

  • Reduction of E. coli O157:H7 in cattle and their manure at the farm is a major factor that would reduce the incidence of E. coli O157 infections in humans


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Concluding Thoughts

  • Certain types of foods are of greatest risk of pathogen contamination

    • Fresh minimally processed foods of animal origin and plant-derived foods having contact with feces

    • Foods prepared by infected food handlers


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Concluding Thoughts

  • Need to address fundamental issues (beyond the food processor and consumer) that contribute substantially to human illnesses caused by animal-borne/foodborne pathogens

    • Example, reduce fecal shedding of E. coli O157:H7 by cattle at the farm


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Solutions to Foodborne Pathogen Contamination of Agricultural Products

  • Get the pathogens out of animal reservoirs, largely in gastrointestinal tract and subsequently in feces

  • Treat poop to kill pathogens before poop contaminates agricultural products

  • Keep poop out of agricultural products

  • Good personal hygiene practices by foodhandlers

  • Cook unprocessed foods well


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Solutions to Foodborne Pathogen Contamination at Food Service

  • Employees

    • Good personal hygiene

    • Good foodhandling practices (cross-contamination, cooking)

    • Food security

  • Thoroughly cook raw foods (ground beef, poultry)

  • Proper equipment sanitation


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Research Opportunities

  • At Production Intervention Strategies

    • Reduce the contamination of:

      • Manure

        • Reduce intestinal carriage of E. coli O157 by cattle; Campylobacter by poultry; Salmonella by poultry, swine, cattle

        • Composting and handling treatments to kill pathogens


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Research Opportunities

  • At Production Intervention Strategies

    • Reduce pathogen contamination of:

      • Fresh produce (domestic and imported)

        • Decontamination treatments that effectively kill pathogens and retain sensory properties

          • Example, mild heat (50oC) treatment of lettuce in 2% H2O2 for 60 seconds


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Research Opportunities

  • At Processing Intervention Strategies

    • Presently, other than possibly heat treatment, there is no universal treatment to eliminate pathogens from foods

      • Need treatments that effectively kill pathogens and retain product quality


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Research Opportunities

  • Foodborne Viruses, Parasites, and nonO157EHEC

    • Detection methods

    • Ecology

    • Treatments of inactivation


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