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

Intervention or Control PointsFood 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

Primary Food ProcessorsProduce (fresh-cut)Meat (slaughter)Poultry (slaughter)

Intervention or Control Points?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

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

ProduceTreatmenta log Salmonella/g (% Reduction)

Shredded Control 3.31 ( 0)

lettuce 120 ppm chlorine 2.53 (83)

200 ppm chlorine 2.49 (85)

Diced Control 3.00 ( 0)

tomatoes 120 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)

Intervention or Control Points

Beef Slaughter Steam vacuuming of fecal contamination

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

Steam pasteurizationReduce pathogens by 10- to 100-fold

Organic acid rinsesReducing pathogens by 10- to 100-fold

Intervention or Control Points

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 PointsFood Processors Innovative technologies other than heat treatment for

killing/controlling pathogens(Examples)High hydrostatic pressureHigh intensity lightPulsed electric fieldsAntimicrobial chemicals/gases (ozone, chlorine dioxide)Hurdles (water activity, pH)Irradiation

Intervention or Control PointsFood 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

Emerging Issues in the Microbiological Safety of Foods

Gamma Irradiation Not a panacea to eliminate pathogens

from all foods

Gamma Irradiation of Ground Beef D-values of pathogens in ground beef (8-14% and 27-28% fat)

subjected to 60Co Gamma irradiation

3 to 5C

(kGy) -17 to -15C

5-D kill

C. jejuni

0.18-0.20

0.21-0.24

1.20

E. coli O157:H7 0.24-0.25 0.31 1.55

S. aureus 0.45 0.44-0.45 2.25

L. monocytogenes 0.57-0.59 0.58-0.61 3.05

Salmonella 0.63-0.66 0.75-0.80 4.00

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

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?

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

47/>5,400CY 2001 (through 10/4)

55/6,374CY 2000

32/7,786CY 1999c

14/8,080CY 1998

4/6,065CY 1997b

4/5,703CY 1996

3/5,407CY 1995

0/891CY 1994a

No. Positive/No. SamplesYear

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

1643 3212 (11) 4515 (21)CY 1999

13 (1) 50 (1) 1292 (17) 5019 (36)CY 2000

1355 3731 (2) 4281 (12)CY 1998

88 (1) 8 4849 (1) 1120 (2)CY 1997

22844 3972 (3) 1459 (1)CY 1996

7029 2787 (1) 2521 (2)CY 1995

010588293 CY 1994

(No. of Samples Analyzed)Year

ImportsState PlantsRetail Stores Federal Plants

Location of Sampling

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

USDA-FSIS

212001 (through 10/12)

272000

41999

71998

21997

11996

No. of RecallsYear

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

a 5 original sites Centers for Disease Control and Prevention

MMWR 50:241 (2001)

2.92000

2.11999

2.81998

2.31997

2.71996

No. of Cases Per 100,000Year

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

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

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

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

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

Quantitative Microbiological Risk Assessment

1. Hazard identification

2. Exposure assessment

3. Dose-response assessment

4. Risk characterization

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

Relative Risk Rankings for Listeriosis Among Food Categories for Three

Subpopulations (Per-Serving Basis)Food Category Intermediate Age Elderly Perinatal

Seafood

Smoked 3 3 3

Raw 14 14 14

Preserved Fish 7 7 6

Cooked, RTE Crustaceans 6 5 5

Produce

Vegetables 17 17 17

Fruit 18 18 18

Relative Risk Rankings for Listeriosis Among Food Categories for Three

Subpopulations (Per-Serving Basis)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 4 4 4

Pt & Meat Spreads 1 2 2

Combination Foods

Deli Salads 5 6 8

Relative Risk Rankings for Listeriosis Among Food Categories for Three

Subpopulations (Per-Serving Basis)Food Category Intermediate Age Elderly Perinatal

Dairy

Soft, Mold-Ripened & 9 9 9

Blue-Veined Cheese

Goat, Sheep & Feta Cheese 16 16 16

Fresh Soft Cheese (quesco fresco) 2 1 1

Heat-Treated Natural/Process Cheese 15 15 15

Aged Cheese 19 19 19

Pasteurized Milk 10 10 10

Unpasteurized Milk 11 11 11

Ice Cream & Frozen Dairy Desserts 20 20 20

Misc. Dairy Products 12 13 13

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

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

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

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

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

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.

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

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

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

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

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

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

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

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

Research Opportunities

Foodborne Viruses, Parasites, and nonO157EHEC Detection methods Ecology Treatments of inactivation