Food Safety Challenges from Farm to Table Michael P. Doyle.
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Transcript of Food Safety Challenges from Farm to Table Michael P. Doyle.
Incidence of Foodborne Illness in United States
Centers for Disease Control and Prevention estimates 76 million cases of foodborne illness annuallyIncludes 325,000 hospitalizations and
5,000 deaths
P. S. Mead et al. 5:607 (1999)
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)
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. 5:607 (1999)
Estimated Number of Cases of Foodborne Illness Annually in United States
Cases from Foodborne Transmission Escherichia coli O157:H7 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. 5:607 (1999)
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. 5:607 (1999)
Leading Bacteriological Causes of Foodborne Illness in USA
Campylobacter jejuni - est. 2 million cases/yrPrincipal vehicles - poultry, unpasteurized milk
Salmonella sp. - est. 1.5 million cases/yrPrincipal vehicles - eggs, poultry, beef, pork, produce
Shigella - est. 90,000 cases/yrPrincipal vehicles - salads, produce (food handler
contamination) E. coli O157:H7 - est. 60,000 cases/yr
Principal vehicles - cattle (handling) and beef, produce, water (recreational and drinking)
Transmission of Foodborne Pathogens
Campylobacter jejuni and Salmonella sp.Carried in intestinal tract of poultry and
other animalsFecal contamination of skin during grow
out and processing Salmonella Enteritidis
–Colonize ovarian tissue of poultry
–Internal contents of eggs are contaminated
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
Transmission of Foodborne Pathogens
E. coli O157:H7Carried in intestinal tract of cattleDirect 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
Risk Factors Associated with Sporadic Cases of E. coli O157:H7
Infection in U.S.
Eating undercooked ground beef Visiting a farm
U.S. Centers for Disease Control and Prevention, 1998
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)
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
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
Prevalence of Campylobacter in Manure
Cattle manureBeef cattle at slaughter 89% prevalence
Poultry manureChickens and turkeys 80-100% prevalence
(depending on flock)
Sheep manureSheep at slaughter high prevalence
Prevalence of Salmonella in Manure
Cattle manure - 10 to 25% of samples
Poultry manure - 29% of samples
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
E. coli O157 in U.S. Feedlots
Prevalence of E. coli O157 in beef fecal samples by month of collection
Oct 99 10.2% Apr 00 15.6%
Nov 99 11.1 May 00 12.1
Dec 99 8.9 Jun 00 15.3
Jan 00 5.7 Jul 00 17.4
Feb 00 3.3 Aug 00 10.7
Mar 00 4.7 Sep 00 19.9
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 O157:H7 102 - 105 — 108 Cryptosporidium 105 - 1010 — 107
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 sewageMilkBeefPoultryPorkEggsProduce (e.g., lettuce, sprouts, fruit juices, cantaloupe,
cilantro)
Types of Foods Most Likely Contaminated with Foodborne Pathogens
Foods prepared by an infected food handlerSaladsSalad bar foodsSandwiches
Emerging Issues in the Microbiological Safety of Foods
Imported Foods
Sanitation practices for food production and preparation are not universally equivalent
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
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 O157:H735 positive for Salmonella 9 positive for Shigella 0 positive for E. coli O157:H7
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
Emerging Issues in the Microbiological Safety of Foods
Antibiotic-Resistant Foodborne PathogensOpportunistic pathogens become
untreatable Vancomycin-resistant enterococci
Prevalent pathogens become life threatening Multi-resistant Salmonella
Emerging Issues in the Microbiological Safety of Foods
Non-O157:H7 enterohemorrhagic E. coliExamples of other serotypes of EHEC
O26:H11 O6:H31
O104:H21 O48:H7
O111:NM O98:NM
O145:NM O103:H2
O157:NM
E. coli O111:NM Outbreaks
23 cases of hemolytic uremic syndrome from January - February 1995 in South Australia
Vehicle was mettwurst (semi-dry sausage)
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
Cyclospora cayetanensis
1996 OutbreakMore than 1500 illnesses in 15 states and
CanadaVehicle - Guatemalan raspberries
Suggested source was untreated water from natural reservoirs used to mix pesticides sprayed on raspberries
Cyclospora cayetanensis
1997 OutbreaksGuatemalan (and possibly Chilean)
raspberries5 states and a cruise ship
Mesclun lettucePesto sauce (basil)
Toxoplasmosis Estimated 112,500 food-associated cases annually
in United StatesEstimated 2,500 hospitalized cases and 375
deaths In Europe, congenital toxoplasmosis affects 1 to 10
in 10,000 newborn babies1 to 2% develop learning disorders or die4 to 27% develop permanent impairment of vision
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 contactContact with cats was not a risk factor
A. J. C. Cook et al. Br. Med. J. 321:142 (2000)
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 < 6 months of age 20.1% positive for Giardia sp. 2.4% positive for C. parvum
S. E. Wade et al. Vet. Parasitol. 93:1 (2000)