Where Must Food Safety Begin

1
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

2
Intervention or Control Points

• Food Producers
• Examples of promising CPs 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

3
Intervention or Control Points

• Primary Food Processors
• Produce (fresh-cut)
• Meat (slaughter)
• Poultry (slaughter)

4
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

5
Effect of chlorinated water on Salmonella on
shredded lettuce and diced tomatoes

• Produce Treatmenta 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.
  62123 (2000)

6
Intervention or Control Points

• 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

7
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

8
Intervention or Control Points

• 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

9
Intervention or Control Points

• 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

10
Emerging Issues in the Microbiological Safety of
Foods

• Gamma Irradiation
• Not a panacea to eliminate pathogens from all
  foods

11
Gamma Irradiation of Ground Beef

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

12
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 (gt10) Undesirable off-
  odor/flavor
• White chicken meat Acceptable
• Lettuce Undesirable texture

13

• 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 O157H7
  Infections in Humans?

14
Number of Confirmed E. coli O157H7-Positive
Ground Beef Samples by USDA-FSIS
No. Positive/No. Samples
Year
0/891
CY 1994a
3/5,407
CY 1995
4/5,703
CY 1996
4/6,065
CY 1997b
14/8,080
CY 1998
32/7,786
CY 1999c
55/6,374
CY 2000
47/gt5,400
CY 2001 (through 10/4)
15
Sites of Sampling for E. coli O157H7 Ground Beef
Testing
Location of Sampling
Imports
State Plants
Retail Stores
Federal Plants

(No. of Samples Analyzed)
Year
0
10
588
293
CY 1994
70
29
2787 (1)
2521 (2)
CY 1995
228
44
1459 (1)
CY 1996
3972 (3)
88 (1)
8
4849 (1)
1120 (2)
CY 1997
13
55
3731 (2)
4281 (12)
CY 1998
16
43
3212 (11)
4515 (21)
CY 1999
13 (1)
50 (1)
1292 (17)
5019 (36)
CY 2000
16
Recalls of Ground Beef for E. coli O157H7
Contamination
No. of Recalls
Year
1
1996
2
1997
7
1998
4
1999
27
2000
21
2001 (through 10/12)
USDA-FSIS
17
Incidence of E. coli O157H7 Infections Based on
FoodNeta
No. of Cases Per 100,000
Year
2.7
1996
2.3
1997
2.8
1998
2.1
1999
2000
2.9
a 5 original sites Centers for Disease
Control and Prevention MMWR 50241 (2001)
18
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

19
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

20
Outbreak Data Indicate Large-Scale E. coli
O157H7 Contamination of Ground Beef

• Testing of Jack-in-the-Box E. coli O157H7
  outbreak revealed 6 of 17 lots produced during
  one day's production were contaminated with E.
  coli O157 Tuttle et al., Epidemiol. Infect.
  122185 (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
  O157H7-negative

21
Could USDA's Approach of Random Testing of Ground
Beef for E. coli O157H7 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

22
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

23
Quantitative Microbiological Risk Assessment

• Hazard identification
• Exposure assessment
• Dose-response assessment
• Risk characterization

24
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

25
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

26
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
• P?t? Meat Spreads 1 2 2
• Combination Foods
• Deli Salads 5 6 8

27
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

28
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 O157H7 infection from ground
  beef
• Proper refrigeration (lt45oF) will prevent
  pathogen from growing on beef carcasses/ pieces
  and limit level of contamination of ground beef

29
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

30

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

31
Risk Factors Associated with Sporadic Cases of E.
coli O157H7 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

32
Risk Factors Associated with E. coli O157H7
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. 36317, 1998

33
Present Understanding of E. coli O157H7

• 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.

34
Missed Opportunity?

• Reduction of E. coli O157H7 in cattle and their
  manure at the farm is a major factor that would
  reduce the incidence of E. coli O157 infections
  in humans

35
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

36
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 O157H7
  by cattle at the farm

37
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

38
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

39
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

40
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

41
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

42
Research Opportunities

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