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Where Must Food Safety Begin?

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?

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  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. 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

  3. Primary Food Processors Produce (fresh-cut) Meat (slaughter) Poultry (slaughter) Intervention or Control Points

  4. 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?

  5. 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. 62:123 (2000) Effect of chlorinated water on Salmonella on shredded lettuce and diced tomatoes

  6. 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

  7. 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

  8. 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

  9. 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

  10. Gamma Irradiation Not a panacea to eliminate pathogens from all foods Emerging Issues in the Microbiological Safety of 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 (>10%) 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 O157:H7 Infections in Humans?

  14. 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

  15. 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)

  16. 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

  17. 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)

  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 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

  21. 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

  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. 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)

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

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

  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 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

  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 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

  32. 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

  33. 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.

  34. 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

  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 O157:H7 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

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