Food Safety Challenges from Farm to Table

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Food Safety Challenges from Farm to Table

• Michael P. Doyle

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Incidence of Foodborne Illness in United States

• Centers for Disease Control and Prevention
  estimates 76 million cases of foodborne illness
  annually
• Includes 325,000 hospitalizations and 5,000
  deaths
• P. S. Mead et al. 5607 (1999)

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Comparison of Estimated Annual Incidence of
Foodborne Illness with Other Illnesses in U.S.

• Illness No. of Cases
• Bronchitis 12 million
• Flu 50 million
• Common cold 62 million
• Foodborne disease 76 million
• CDC estimates (2000)

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Estimated Number of Cases of Foodborne Illness
Annually in United States

• Cases from Foodborne Transmission
• Norwalk-like viruses 9, 200,000
• Campylobacter spp. 1,963,000
• Salmonella (nontyphoid) 1,332,000
• Clostridium perfringens 248,500
• Giardia lamblia 200,000
• Staphylococcus food poisoning 185,000
• Toxoplasma gondii 112,500
• Shigella spp. 90,000
• Yersinia enterocolitica 86,800
• P. S. Mead et al. Emerging Infect. Dis. 5607
  (1999)

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Estimated Number of Cases of Foodborne Illness
Annually in United States

• Cases from Foodborne Transmission
• Escherichia coli O157H7 62,500
• Enterotoxigenic E. coli 55,600
• Streptococcus 51,000
• Astrovirus 39,000
• Rotavirus 39,000
• Shiga-toxin producing E. coli (nonO157)
  31,000
• Bacillus cereus 27,400
• E. coli (other diarrheic)
  23,900
• Cyclospora cayetanensis 14,600
• P. S. Mead et al. Emerging Infect. Dis. 5607
  (1999)

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Estimated Number of Cases of Foodborne Illness
Annually in United States

• Cases from Foodborne Transmission
• Vibrio parahaemolyticus 5,000
• Hepatitis A 4,200
• Listeria monocytogenes 2,500
• Brucella sp. 780
• Botulism 60
• Trichinella spiralis 50
• Vibrio cholerae 50
• Vibrio vulnificus 50
  
• P. S. Mead et al. Emerging Infect. Dis. 5607
  (1999)

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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
• Shigella - est. 90,000 cases/yr
• Principal vehicles - salads, produce (food
  handler contamination)
• E. coli O157H7 - est. 60,000 cases/yr
• Principal vehicles - cattle (handling) and
  beef, produce, water (recreational and drinking)

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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

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Risk Factors for Sporadic Campylobacter
Infections in the United States

• 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

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Transmission of Foodborne Pathogens

• E. coli O157H7
• 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

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Risk Factors Associated with Sporadic Cases of E.
coli O157H7 Infection in U.S.

• Eating undercooked ground beef
• Visiting a farm
• U.S. Centers for Disease Control and Prevention,
  1998

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Agricultural Practices

• Major sources of foodborne pathogen contamination
  of agricultural products are (1) animal manure
  and (2) human feces (e.g., produce harvesting and
  handling)

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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

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The U.S. Manure Glut (1997 estimates)

• 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

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Prevalence of Campylobacter in Manure

• 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

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Prevalence of Salmonella in Manure

• Cattle manure - 10 to 25 of samples
• Poultry manure - 29 of samples

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E. coli O157 in U.S. Feedlots

• USDA National Animal Health Monitoring System
  determined prevalence of E. coli O157 in beef
  feedlots in 11 western and midwestern states
  during Oct 99 - Sept 00
• 11.0 (1,148/10,415) of fecal samples were E.
  coli O157-positive
• USDA-APHIS, Fort Collins, CO. E. coli O157 in
• United States Feedlots, October 2001

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E. coli O157 in U.S. Feedlots

• Prevalence of E. coli O157 in beef fecal samples
  by month of collection

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Reported Levels of Pathogens in Animal Manures

• Pathogen Animal
• Cattle Poultry Sheep
• (CFU or Oocysts/g)
• Campylobacter 104 - 108 104 -
  107 up to 105
• Salmonella up to 108 - 1010 104 - 107
• E. coli O157H7 102 - 105
  108
• Cryptosporidium 105 - 1010 107

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• What types of foods are most likely
• to be contaminated with foodborne
• pathogens?

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Types of Foods Most Likely Contaminated with
Foodborne Pathogens

• Fresh (unpasteurized) foods of animal origin and
  plant-derived foods having contact with manure or
  human sewage
• Milk
• Beef
• Poultry
• Pork
• Eggs
• Produce (e.g., lettuce, sprouts, fruit juices,
  cantaloupe, cilantro)

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Types of Foods Most Likely Contaminated with
Foodborne Pathogens

• Foods prepared by an infected food handler
• Salads
• Salad bar foods
• Sandwiches

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Emerging Issues in the Microbiological Safety of
Foods

• Imported Foods
• Sanitation practices for food production and
  preparation are not universally equivalent

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Major Concern RegardingImported Food

• Pathogens on produce
• Sources
• Irrigation water
• Processing water
• Poor personal hygiene of infected
  foodhandlers
• Sewage/manure used as soil fertilizer
• (Example) Shigellosis from Mexican-grown parsley

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Prevalence of Salmonella and Shigella on Imported
Produce

• FDA assayed 1003 imported produce samples from
  March 99 - October 00 for Salmonella, Shigella
  and E. coli O157H7
• 35 positive for Salmonella
• 9 positive for Shigella
• 0 positive for E. coli O157H7

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Prevalence of Salmonella and Shigella on Imported
Produce

• Produce Type No. Sampled No. Positive
• Broccoli 36 0
• Cantaloupe 151 11
• Celery 84 3
• Cilantro 177 16
• Culantro 12 6
• Lettuce (loose-leaf) 116 2
• Parsley 84 2
• Scallions 180 3
• Strawberries 143 1
• Tomatoes 20 0
• Total 1003 44

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Emerging Issues in the Microbiological Safety of
Foods

• Antibiotic-Resistant Foodborne Pathogens
• Opportunistic pathogens become untreatable
• Vancomycin-resistant enterococci
• Prevalent pathogens become life threatening
• Multi-resistant Salmonella

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Emerging Issues in the Microbiological Safety of
Foods

• Non-O157H7 enterohemorrhagic E. coli
• Examples of other serotypes of EHEC
• O26H11 O6H31
• O104H21 O48H7
• O111NM O98NM
• O145NM O103H2
• O157NM

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E. coli O111NM Outbreaks

• 23 cases of hemolytic uremic syndrome from
  January - February 1995 in South Australia
• Vehicle was mettwurst (semi-dry sausage)

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Emerging Issues in the Microbiological Safety of
Foods

• Foodborne Parasites
• Global trade and a penchant for fresh,
  uncooked/undercooked foods can be a dangerous
  combination

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Cyclospora cayetanensis

• 1996 Outbreak
• More than 1500 illnesses in 15 states and Canada
• Vehicle - Guatemalan raspberries
• Suggested source was untreated water from natural
  reservoirs used to mix pesticides sprayed on
  raspberries

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Cyclospora cayetanensis

• 1997 Outbreaks
• Guatemalan (and possibly Chilean) raspberries
• 5 states and a cruise ship
• Mesclun lettuce
• Pesto sauce (basil)

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Toxoplasmosis

• Estimated 112,500 food-associated cases annually
  in United States
• Estimated 2,500 hospitalized cases and 375 deaths
• In Europe, congenital toxoplasmosis affects 1 to
  10 in 10,000 newborn babies
• 1 to 2 develop learning disorders or die
• 4 to 27 develop permanent impairment of vision

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Toxoplasma Infection in European Pregnant Women

• Case-control study in 6 European cities to
  identify risk factors associated with
  toxoplasmosis in pregnancy
• Results
• Between 30 and 63 of infections at different
  centers were attributed to consumption of
  undercooked (lamb, beef or game) and cured meat
  products
• 6 to 17 were attributed to soil contact
• Contact with cats was not a risk factor
• A. J. C. Cook et al. Br. Med. J. 321142 (2000)

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Prevalence of Giardia and Cryptosporidium in
Dairy Herds

• Assayed for parasites 2943 fecal samples from
  cattle on 109 dairy farms
• 8.9 positive for Giardia sp.
• 0.9 positive for Cryptosporidium parvum
• 1.1 positive for Cryptosporidium muris
• Calves lt 6 months of age
• 20.1 positive for Giardia sp.
• 2.4 positive for C. parvum
• S. E. Wade et al. Vet. Parasitol. 931 (2000)

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Emerging Issues in the Microbiological Safety of
Foods

• Foodborne Viruses
• A major but highly underreported cause of
  foodborne illness
• CDC estimates 9.2 million foodborne cases of
  Norwalk-like virus annually in U.S.