1. Food Safety Challenges from Farm to Table
Michael P. Doyle

2. 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. 5:607 (1999)

3. Comparison of Estimated Annual Incidence of Foodborne Illness with Other Illnesses in U.S.
Illness No. of Cases
Bronchitis million
Flu million
Common cold million
Foodborne disease 76 million
CDC estimates (2000)

4. Estimated Number of Cases of Foodborne Illness Annually in United States
Cases from Foodborne Transmission
Norwalk-like viruses 9, 200,000
Campylobacter spp ,963,000
Salmonella (nontyphoid) 1,332,000
Clostridium perfringens ,500
Giardia lamblia ,000
Staphylococcus food poisoning ,000
Toxoplasma gondii ,500
Shigella spp ,000
Yersinia enterocolitica ,800
P. S. Mead et al. Emerging Infect. Dis. 5:607 (1999)

5. Estimated Number of Cases of Foodborne Illness Annually in United States
Cases from Foodborne Transmission
Escherichia coli O157:H ,500
Enterotoxigenic E. coli ,600
Streptococcus ,000
Astrovirus ,000
Rotavirus ,000
Shiga-toxin producing E. coli (nonO157) ,000
Bacillus cereus ,400
E. coli (other diarrheic) ,900
Cyclospora cayetanensis ,600
P. S. Mead et al. Emerging Infect. Dis. 5:607 (1999)

6. Estimated Number of Cases of Foodborne Illness Annually in United States
Cases from Foodborne Transmission
Vibrio parahaemolyticus 5,000
Hepatitis A ,200
Listeria monocytogenes 2,500
Brucella sp
Botulism
Trichinella spiralis
Vibrio cholerae
Vibrio vulnificus
P. S. Mead et al. Emerging Infect. Dis. 5:607 (1999)

7. 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 O157:H7 - est. 60,000 cases/yr
Principal vehicles - cattle (handling) and beef, produce, water (recreational and drinking)

8. 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

9. 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
C. Friedman et al. Abstr. Int Conf Emerg Infect Dis 2000 No P

10. 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

11. Risk Factors Associated with Sporadic Cases of E
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

12. 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)

13. 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”

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

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

16. Prevalence of Salmonella in Manure
Cattle manure to 25% of samples
Poultry manure % of samples

17. 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

18. 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

19. Reported Levels of Pathogens in Animal Manures
Pathogen Animal
Cattle Poultry Sheep
(CFU or Oocysts/g)
Campylobacter up to 105
Salmonella up to
E. coli O157:H — 108
Cryptosporidium — 107

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

21. 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)

22. Types of Foods Most Likely Contaminated with Foodborne Pathogens
Foods prepared by an infected food handler
Salads
Salad bar foods
Sandwiches

23. Emerging Issues in the Microbiological Safety of Foods
Imported Foods
Sanitation practices for food production and preparation are not universally equivalent

24. Major Concern Regarding Imported 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

25. 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:H7
35 positive for Salmonella
9 positive for Shigella
0 positive for E. coli O157:H7

26. Prevalence of Salmonella and Shigella on Imported Produce
Produce Type No. Sampled No. Positive
Broccoli
Cantaloupe
Celery
Cilantro
Culantro
Lettuce (loose-leaf)
Parsley
Scallions
Strawberries
Tomatoes
Total

27. 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

28. Emerging Issues in the Microbiological Safety of Foods
Non-O157:H7 enterohemorrhagic E. coli
Examples of other serotypes of EHEC
O26:H11 O6:H31
O104:H21 O48:H7
O111:NM O98:NM
O145:NM O103:H2
O157:NM

29. E. coli O111:NM Outbreaks
23 cases of hemolytic uremic syndrome from January - February 1995 in South Australia
Vehicle was mettwurst (semi-dry sausage)

30. 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

31. 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

32. Cyclospora cayetanensis
1997 Outbreaks
Guatemalan (and possibly Chilean) raspberries
5 states and a cruise ship
Mesclun lettuce
Pesto sauce (basil)

33. 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

34. 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. 321:142 (2000)

35. 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)

36. 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.