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Keeping Foodborne Pathogens Down on the Farm

Keeping Foodborne Pathogens Down on the Farm. Michael P. Doyle. Leading Bacteriological Causes of Foodborne Illness in USA . Campylobacter jejuni - est. 2 million cases/yr Principal vehicles - poultry, unpasteurized milk Salmonella sp. - est. 1.5 million cases/yr

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Keeping Foodborne Pathogens Down on the Farm

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  1. Keeping Foodborne Pathogens Down on the Farm Michael P. Doyle

  2. Leading Bacteriological Causes of Foodborne Illness in USA • Campylobacter jejuni - est. 2 million cases/yr • Principal vehicles - poultry, unpasteurized milk • Salmonella sp. - est. 1.5 million cases/yr • Principal vehicles - eggs, poultry, beef, pork, produce • E. coli O157:H7 - est. 60,000 cases/yr • Principal vehicles - cattle (handling) and beef, produce, water (recreational and drinking)

  3. Transmission of Foodborne Pathogens • Campylobacter jejuni and Salmonella sp. • Carried in intestinal tract of poultry and other animals • Fecal contamination of skin during grow out and processing • Salmonella enteritidis • Colonize ovarian tissue of poultry • Internal contents of eggs are contaminated

  4. Transmission of Foodborne Pathogens • E. coli O157:H7 • Carried in intestinal tract of cattle • Direct or indirect contact with cattle manure is likely most frequent origin • Manure can contaminate food through: • . Use of manure as a soil fertilizer • . Polluted irrigation water • . Defecation of cattle in vicinity of produce or foods of animal origin

  5. Approximately 7,500 adults in CA, CT, GA, MN and OR were interviewed by telephone between July 1996 and June 1997 30% ate pink hamburger 18% ate running eggs 1.9% ate raw shellfish 1.5% drank raw milk 7% did not wash cutting board after cutting raw chicken 7% did not wash their hands after handling raw meat or poultry B. Shiferaw et al. J. Food Protect. 63:1538 (2000) Prevalence of Risk Factors for Foodborne Illnesses in the General Population

  6. Case-control study of 6 FoodNet sites from Jan 98 - Mar 99 involving 1463 patients with Campylobacter infection and 1317 controls Risk factors include: Foreign travel Eating undercooked poultry Eating chicken or turkey cooked outside the home Eating nonpoultry meat cooked outside the home Eating raw seafood Drinking raw milk Living on or visiting a farm Contact with farm animals Contact with puppies C. Friedman et al. Abstr. Int Conf Emerg Infect Dis 2000 No. 63. P. 149-150 Risk Factors for Sporadic Campylobacter Infections in the United States

  7. Risk Factors for Fluoroquinolone-Resistant Campylobacter Infections • Case-control study of 7 FoodNet sites from 1998-99 • 94 of 858 (11%) isolates from Campylobacter infections were fluoroquinolone-resistant • Risk factors include: • Eating chicken or turkey cooked at a commercial establishment • Storing raw chicken in refrigerator without plate to catch drippings • Travel outside the United States H. Kassenborg et al. Abstr. Int Conf Emerg Infect Dis 2000 No. 63, P. 150

  8. Eating undercooked ground beef Visiting a farm U.S. Centers for Disease Control and Prevention, 1998 Risk Factors Associated with Sporadic Cases of E. coli O157:H7 Infection in U.S.

  9. 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

  10. Risk Factor Associated with E. coli O157:H7 Infections in Sweden Risk Factor • Contact with farm animals and farms Swedish Government Recommendations • Between June 1 to October 31, farmers with cattle, sheep or goats should avoid: • Visits to animal houses by unauthorized people, especially children under the age of 5 avoid contact with cattle • Consuming unpasteurized milk and dairy products • Contact between grazing animals and humans sunbathing on nearby beaches B. de Jong, Smittskydd 4:48, 1998

  11. Risk Factor Associated with Shiga Toxin-Producing E. coli Infections in Canada • Determined spatial relationship between livestock density and human STEC incidence • Based on 3001 cases of STEC (>95% E. coli O157:H7) infection from 1990 - 95 in Ontario, Canada Michel et al. Epidemiol. Infect. 122:193 (1999)

  12. Risk Factors Associated with STECInfections in Canada • Results: • Areas with high incidence of STEC cases were situated predominantly in areas of mixed agriculture (high in rural areas compared to urban areas) • Cattle density had a positive association with incidence of STEC cases • Elevated risk of STEC infection in rural populations associated with living in areas with high cattle density

  13. Risk Factors Associated with STECInfections in Canada • Conclusions: • Importance of contact with cattle and cattle manure likely has been previously underestimated as a risk factor for STEC infections

  14. Calf to Human Transmission of E. coli O157:H7 1. 13-month-old boy hospitalized with bloody diarrhea in October 1992; lived on dairy farm in SW Ontario - E. coli O157:H7 phagetype 23 isolated from stool 2. Boy placed on straw between calves while mother did barn chores - Boy frequently touched calves and put his fingers in their mouths and his 3. Fecal culture of 1 of 7 calves tested positive from E. coli O157:H7 phagetype 23 Renwick et al. J. Infect. Dis. 168:792 (1993)

  15. E. coli O157:H7 Transmissionvia a Dog 1. Three-year-old U.K. girl developed E. Coli O157:H7 infection after petting a dog at a farm visitor center 2. Girl had no other contact with animals or dirt 3. An identical strain of O157:H7 was recovered from cattle on the farm Parry et al. 1995. Lancet 346:8974

  16. E. coli O157:H7 Infection from Vegetables 1. 39-year-old lacto-ovo-vegetarian woman in Maine had E. coli O157:H7 infection 2. She lived on a farm and her diet consisted almost exclusively of vegetables from her garden - Garden fertilized with manure from calf and cow 3. E. coli O157:H7 was isolated manured soil from the garden Cieslak et al., Lancet 342:367 (1993)

  17. 51 cases of E. coli O157:H7 infection associated with visiting a petting farm in Pennsylvania during Sept-Nov 2000 16 patients hospitalized, 8 with HUS Case-control study identified physical contact with cattle as major risk factor (OR = 10.94) Hand washing before eating was protective (OR = 0.23) O157:H7 isolates from humans, 27 of 216 (13%) cattle and a handrailing all had same PFGE profile Household survey estimated that 7,000 people developed diarrhea associated with visiting the farm J. A. Crump et al. Centers for Disease Control and Prevention (2001) Outbreak of E. coli O157:H7 Infections Associated with Farm Visits

  18. The Manure Glut: A Growing Environmental Threat • Five tons of animal manure is produced annually nationwide for every person living in the United States • The amount of animal manure is 130 times greater than the amount of human waste produced • Cattle, hogs, chickens and turkey produced an estimated 1.36 billion tons of manure in 1997 Democratic Staff of U.S. Senate Agriculture Committee (1998) “Animal Waste Pollution in America: An Emerging National Problem”

  19. Animal Solid Waste (Tons/yr) Cattle 1,229,190,000 Hogs 112,652,300 Chickens 14,394,000 Turkeys 5,425,000 TOTAL 1.36 billion The U.S. Manure Glut (1997 estimates)

  20. Cattle manure Beef cattle at slaughter 89% prevalence Poultry manure Chickens and turkeys 80-100% prevalence (depending on flock) Sheep manure Sheep at slaughter high prevalence Prevalence of Campylobacter in Manure

  21. Cattle manure - 10 to 25% of samples Poultry manure - 29% of samples Prevalence of Salmonella in Manure

  22. Cattle manure Weaned dairy calves 5% Unweaned dairy calves 2% Cattle at slaughter 13-28% Prevalence of E. coli O157:H7 in Manure

  23. Pathogen Animal Cattle Poultry Sheep (CFU or Oocysts/g) Campylobacter 104 - 108 104 - 107 up to 105 Salmonella up to 108 - 1010 104 - 107 no information E. coli O157:H7 102 - 105 — 108 Cryptosporidium 105 - 1010 — 107 Reported Levels of Pathogens in Animal Manures

  24. Storage Temperature Decimal Reduction Time (oC) (Days) 4 13-20 20 9-25 37 2-8 S. Himathongkham et al. FEMS Microbiol Lett 178:251 (1999) Fate of Salmonella in Cattle Manure

  25. Detected by enrichment Survival of E. coli O157:H7 in Bovine Feces 37oC  22oC  5oC 

  26. Survival of E. coli O157:H7 inSheep Manure • Manure pile (7 m long by 3 m wide by 0.6 m deep) collected from sheep experimentally administered E. coli O157:H7; held undisturbed (not aerated) for 21 months • O157 isolated consistently for 12 months (except for November) from middle and bottom moist layers but not from dry feces at top • O157:H7 counts ranged from <102 to 2.2 x 106 cfu/g • O157 detected in 1 of 24 manure samples at 21 months I. T. Kudva et al. Appl. Environ. Microbiol. 64:3166 (1998)

  27. E. coli O157:H7 Infection Associatedwith Well Water and Infected Cattleon a Dairy Farm • 16-month old child from dairy farm hospitalized with bloody diarrhea • E. coli O157:H7 isolated from: • Child's stool • 63% of cattle on the farm • Well water • Well water was contaminated with cattle manure S. G. Jackson et al., Epidemiol. Infect. 120:17, 1998

  28. Lake-Associated Outbreak ofE. coli O157:H7 Infection 1. 12 cases of E. coli O157:H7 infection during June - July 1995 in Illinois 2. Acquired infection by swimming in a lake at an Illinois State Park - Case-control study revealed that risk for illness was associated with taking lake water into the mouth and swallowing lake water CDC, Morbid. Mortal. Weekly Rep. 45(21):437 (May 31, 1996)

  29. Association of E. coli O157:H7 with Water • Drinking and recreational (swimming) waters have been identified as vehicles of E. coli O157 • Sources of contamination include: • Cattle manure seeping into well water or lakes • Children defecating in a lake and swimming pool

  30. Survival of E. coli O157:H7 in Water • E. coli O157 can survive for a long period of time in water, especially at cold temperatures • Survival for more than 13 weeks in water at 8EC, with only a 10-to-100-fold reduction • Precautions should be taken when using lake or river waters for drinking or recreational purposes

  31. Association of E. coli O157:H7 with Deer • During July - August 1997, 310 fresh deer fecal samples collected from ground at 5 Georgia wildlife management areas • No isolations of E. coli O157:H7 J. R. Fischer et al., University of Georgia

  32. Association of E. coli O157:H7 with Deer • During autumn 1997, 371 fecal samples collected directly from hunter-killed deer at 6 Georgia wildlife management areas • E. coli O157:H7 isolated from 3 deer • All from deer in NW Georgia in vicinity of cattle • Two different PFGE DNA fingerprints J. R. Fischer et al., University of Georgia

  33. Association of E. coli O157:H7 with Deer • During autumn 1998, 140 fecal samples collected directly from hunter-killed deer at NW Georgia location in vicinity of cattle • No isolations of E. coli O157:H7 • During same time period, 231 fecal samples collected directly from cattle present in vicinity of deer • E. coli O157:H7 isolated from 12 (5.2%) cattle J. R. Fischer et al., University of Georgia

  34. Public Health Issues Associated Human Pathogens Carried by Animals • Contaminated food from animals • Meat, eggs, milk • Contaminated food that contacts animal waste • Vegetables and fruit grown in soil fertilized with animal manure or treated with irrigation water with animal waste • Contaminated water containing animal waste • Untreated drinking water and swimming in recreational lakes

  35. Methods of Control for E. coli O157 • Low infectious dose of E. coli O157 necessitates reducing or eliminating pathogen, rather than solely preventing its growth • HACCP system most effective approach for reducing risk of E. coli O157 infections • Most desirable HACCP system includes a step that kills pathogens • For raw foods that do not receive a terminal kill treatment, HACCP systems must be implemented throughout food continuum, from farm to table

  36. 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

  37. Food Producers Examples of 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

  38. Control of E. coli O157:H7 in Cattle by Competitive Exclusion Bacteria • Competitive exclusion involves use of microbial cultures that out-compete pathogens from colonizing specific niches • Principal sites of E. coli O157 localization in cattle are the animal’s three forestomachs and the large intestine • Isolates of E. coli that produce antimicrobials to E. coli O157 and localize in the same sites of bovine GI tract as E. coli O157 can eliminate or reduce carriage of E. coli O157 in ruminating calves

  39. Recovery of E. coliO157:H7 at necropsy (13 to 27 days postinoculation) from experimentally infected calves No. Range Meana Sample positive/ (CFU/gram) (CFU/gram) Site total contents contents Rumen 9 / 9 <0.5 X 101 - 3.2 X 103 3.8 X 102 Recticulum 7 / 9 <0.5 X 101 - 2.5 X 103 4.1 X 102 Omasum 9 / 9 <0.5 X 101 - 2.5 X 103 2.9 X 102 Abomasum 0 / 9 0 0 Duodenum 2 / 9 <0.5 X 101 <0.5 X 101 Ileum 4 / 9 <0.5 X 101 - 4.0 X 101 1.4 X 101 Distal cecum 7 / 9 <0.5 X 101 - 2.5 X 101 0.8 X 101 Spiral colon 7 / 9 <0.5 X 101 - 6.3 X 102 1.2 X 102 Descending 5 / 9 <0.5 X 101 - 2.5 X 102 6.8 X 101 colon

  40. Protocol • 20 adult steers (weight 980-1160 lbs) were fed production diet containing monensin (30g/ton) • Each administered by gavage 1010E. coli O157 (5-strain mixture) at day 0 • 10 steers administered at 48 and 72 h post-challenge 1010 probiotic E. coli (3 strains) • E. coli O157 and probiotic bacteria fecal shedding monitored until day 33

  41. E. coli O157:H7 (log CFU/g) in feces of cattle administered E. coli O157:H7 only

  42. E. coli O157:H7 (log/g) at necropsy (day 33) in cattle administered E. coli O157:H7 only Rumen Rumen Colon Colon Feces Steer No. content tissue content tissue 3.6 3.1 4.8 5.0 5.1 1 4 1.5 1.5 1.6 <2.4 1.3 5 <1.1 1.1 <2.4 <2.4 <1.1 8 3.1 2.6 4.9 5.2 5.7 11 <1.1 1.2 <1.1 4.3 <1.1 13 <1.1 1.5 2.4 4.8 <1.1 16 <1.1 2.5 <1.1 3.4 <1.1 17 3.4 1.9 1.2 <2.4 <1.1 21 <1.1 1.5 1.4 3.1 1.0 <2.4 24 <1.1 1.2 1.4 <1.1

  43. E. coli O157:H7 (log/g) in feces of cattle administered E. coli O157:H7 and probiotic bacteria Steer No. Day 2 Day 12 Day 21 Day 30 2 4.7 <1.1 <2.4 <1.1 3 4.7 <1.1 <2.4 <1.1 6 4.9 <1.1 2.1 <1.1 7 3.6 <1.1 <2.4 <1.1 9 5.5 <1.1 <2.4 <1.1 10 5.3 <1.1 <2.4 <1.1 15 4.4 <1.1 <2.4 <2.4 18 3.4 <1.1 <2.4 <1.1 20 3.7 <1.1 <2.4 <2.4 22 5.0 <1.1 <1.1 <1.1

  44. E. coli O157:H7 (log/g) at necropsy (day 33) in cattle administered E. coli O157:H7 and probiotic bacteria Rumen Rumen Colon Colon Steer No. content tissue content tissue Feces 2 <1.1 <1.1 <1.1 <2.4 <1.1 3 2.5 1.6 <1.1 <2.4 <1.1 6 <1.1 <1.1 <1.1 <2.4 <1.1 7 <1.1 <1.1 <1.1 <2.4 <1.1 9 <1.1 <1.1 <1.1 <2.4 <1.1 10 <1.1 <1.1 <1.1 <2.4 <1.1 15 <1.1 <1.1 <1.1 <2.4 <2.4 18 <1.1 <1.1 <1.1 <2.4 <1.1 20 <1.1 <1.1 <1.1 <2.4 <2.4 22 <1.1 <1.1 <1.1 <2.4 <1.1

  45. Six bacteriophage (1011 pfu) capable of lysing most E. coli O157:H7 strains were orally administered at -7, -6, 0 and 1 day to 6-week old calves (5 per group) per orally administered 3x109E. coli O157:H7 on day 0 Phage-treated calves shed fewer E. coli O157 on day 2, 4 and 6 than calves fed E. coli O157 only, and E. coli O157 was not shed after day 8 4 of 5 calves fed E. coli O157 shed O157 for 10 to 16 days T. Waddell et al. Abstr. VTEC 2000, No. 179 (2000) Bacteriophage Treatment of E. coli O157:H7 Infection of Calves

  46. Control of E. coli O157:H7 in Cattle by Vaccination • Vaccination involves exposing animal to attenuated pathogen or antigen of a virulent microorganism to produce immunity • Traditional approaches to vaccinate cattle against E. coli O157 are not likely to be successful • Innovative vaccines may be useful • Example, insert genes of virulence factors of E. coli O157 into alfalfa to stimulate production of IgA in GI tract

  47. Edible Vaccine in Potatoes • Potatoes were genetically engineered to produce B subunit of E. coli heat labile enterotoxin • Results of volunteers who ingested transgenic potatoes: • 10 of 11 had a 4-fold increase in serum (IgG) antibodies • 6 of 11 had a 4-fold increase in intestinal (IgA) antibodies

  48. Control of E. coli O157:H7 in Cattle by Farm Management Practices • Water troughs are on-farm sources of E. coli O157 contamination from cattle manure and cud • Need frequent cleaning of water troughs and improved design of cattle water reservoirs to reduce contamination

  49. Effect of Diet on Carriage of E. coli O157:H7 by Cattle • Eight 1- to 2-year-old Holstein steers were fed finishing diets of 82 to 90% grain (barley/corn), 100% alfalfa hay or 100% timothy grass (modified crossover design) • Administered 1010E. coli O157:H7 via gastric tube into rumen to each steer 3 weeks after adaption to a particular diet C. J. Hovde et al. Appl. Environ. Microbiol. 65:3233 (1999)

  50. Effect of Diet on Carriage of E. coli O157:H7 by Cattle • Average duration of fecal shedding of E. coli O157:H7: Grain diet 4 days Alfalfa diet 39 days Timothy grass diet 42 days • Acid resistance of E. coli O157:H7 was unaffected by diets C. J. Hovde et al. Appl. Environ. Microbiol. 65:3233(1999)

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