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 annually Includes 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 Flu Common cold Foodborne disease 12 million 50 million 62 million 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 Hepatitis A Listeria monocytogenes Brucella sp. Botulism Trichinella spiralis Vibrio cholerae Vibrio vulnificus 5,000 4,200 2,500 780 60 50 50 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/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) 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 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: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 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 Hogs Chickens Turkeys 1,229,190,000 112,652,300 14,394,000 5,425,000 TOTAL 1.36 billion Prevalence of Campylobacter in Manure Cattle manure Beef cattle at slaughter Poultry manure Chickens and turkeys Sheep manure Sheep at slaughter 89% prevalence 80-100% prevalence (depending on flock) 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 Nov 99 Dec 99 Jan 00 Feb 00 Mar 00 10.2% 11.1 8.9 5.7 3.3 4.7 Apr 00 May 00 Jun 00 Jul 00 Aug 00 Sep 00 15.6% 12.1 15.3 17.4 10.7 19.9 Reported Levels of Pathogens in Animal Manures Pathogen Animal Cattle Poultry (CFU or Oocysts/g) Campylobacter 104 - 108 Salmonella up to 108 - 1010 E. coli O157:H7 102 - 105 Cryptosporidium 105 - 1010 104 - 107 104 - 107 — — Sheep up to 105 108 107 What types of foods are most likely to be contaminated with foodborne pathogens? 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) Types of Foods Most Likely Contaminated with Foodborne Pathogens Foods prepared by an infected food handler Salads Salad bar foods Sandwiches Emerging Issues in the Microbiological Safety of Foods Imported Foods Sanitation practices for food production and preparation are not universally equivalent 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 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 Prevalence of Salmonella and Shigella on Imported Produce Produce Type Broccoli Cantaloupe Celery Cilantro Culantro Lettuce (loose-leaf) Parsley Scallions Strawberries Tomatoes Total No. Sampled 36 151 84 177 12 116 84 180 143 20 1003 No. Positive 0 11 3 16 6 2 2 3 1 0 44 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 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 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 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 Cyclospora cayetanensis 1997 Outbreaks Guatemalan (and possibly Chilean) raspberries 5 states and a cruise ship Mesclun lettuce Pesto sauce (basil) 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 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) 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) 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.