Epidemiology and Risk Assessment

1. Epidemiology and Risk Assessment Morris Potter Center for Food Safety and Applied Nutrition Food and Drug Administration

2. Epidemiology and Risk Assessment • Incidence of diseases that may be foodborne • Proportion of these diseases that are foodborne • Major food vehicles of transmission • Characterization of conditions under which foodborne transmission occurs

3. Risk Assessment • Hazard identification • Exposure assessment • Hazard characterization (dose-response) • Risk characterization

4. Epidemiology • Outbreak investigations • Studies of sporadic foodborne disease • Surveillance of human diseases • Surveillance of pathogens in foods

5. Incidence of Potentially Foodborne Diseases • Surveillance that is • Passive • Active • Surveillance that is • Based on clinical diagnosis • Based on laboratory confirmation from human clinical specimens • Known population denominator permits calculation of rates of illness

6. 12 10 8 Number/100,000 pop. 6 4 2 0 1970 72 74 76 78 80 82 84 86 88 90 92 94 96 98 Year Total New England Mid Atlantic Pacific Other Mountain Salmonella Enteritidis Incidence by Region, United States, 1970-99 CDC PHLIS data

7. Food-related Illness and Death in the United States 76 million illnesses 323,000 hospitalizations 5,000 deaths First comprehensive estimates by CDC Based on passive nationwide surveillance, medical literature, early FoodNet statistics, and expert elicitation Used for new cost estimates, risk-assessment, model for other disease estimates

8. Food-related Illness and Death in the United States

9. FoodNet: Foodborne Disease Active Surveillance Network YEAR POPULATION (in millions) 1996 14.3 1997 16.1 1998 20.7 1999 25.9 2000 30.5 2001 34.3 2002 36.1 2003 37.4 13% of U.S. population

10. Active Surveillance • 7 bacterial pathogens:Campylobacter, E. coli O157, Listeria, Salmonella, Shigella, Vibrio, and Yersinia • 2 parasitic organisms:Cryptosporidium and Cyclospora • 3 syndromata:Hemolytic Uremic Syndrome (HUS), Guillain Barré Syndrome (GBS),congenital toxoplasmosis • Foodborne disease outbreaks

11. FoodNet Helps Estimate Missing Data

12. Incidence of Infections with Pathogens under Surveillance, FoodNet 2002 Pathogen Cases per 100,000 persons Salmonella 16.1 Campylobacter 13.4 Shigella 10.3 E. coli O157 1.7 Cryptosporidium 1.4 Yersinia 0.44 Vibrio 0.27 Listeria 0.26 Cyclospora 0.11

13. Relative Rates of Laboratory-Diagnosed Cases of Campylobacter,Listeria, & Yersinia, By Year 1996 - 2002

14. Relative Rates of Laboratory-Diagnosed Cases of Salmonella,E. coli O157, & Shigella, By Year, 1996 - 2002

15. Incidence of Campylobacter and Salmonella Infections in FoodNet by Age Group

16. Percentage of Cases Hospitalized, FoodNet, by Pathogen

17. Epidemiology and Risk Assessment • Incidence of diseases that may be foodborne • Proportion of these diseases that are foodborne • Major food vehicles of transmission • Characterization of conditions under which foodborne transmission occurs

18. Incidence of Foodborne Disease • Expert elicitation – Proportion foodborne • Population-based sporadic case studies – Specific attribution

19. Foodborne Disease Outbreaks, Passive Nationwide System, United States, 2000 Etiology Number Number Outbreaks Cases Bacterial 226 6528 Chemical 37 185 Parasitic 6 169 Viral 176 7208 Multiple Etiologies 3 22 Total Confirmed Etiology 448 14112 Total Unknown Etiology 969 11931 Total 2000 1417 26043

20. Outbreaks Reported to FoodNet and Nationwide Surveillance System, 1998-1999 FoodNet Passive Rate/million population 10.3 4.5 Known etiology 30% 28% Salmonella 11% 32% Shigella 2% 4% E. coli O157 1% 7%

21. Incidence of diseases that may be foodborne Proportion of these diseases that are foodborne Major food vehicles of transmission Characterization of conditions under which foodborne transmission occurs Epidemiology and Risk Assessment

22. Major Food Vehicles • Sometimes the biology of the agent identifies the vehicle • For other pathogens • Outbreak investigations • Sporadic case studies • Pathogen surveillance in foods

23. Major Food Vehicles for Specific Foodborne Pathogens Outbreak investigations Sporadic case-control studies Food microbiology-based surveillance

24. Sporadic Case Studies • Sporadic cases generally more common • May have different epidemiologic characteristics and control strategies • Studied by same methods as outbreaks but more difficult without clustering of cases • FoodNet primarily established as a vehicle to study sporadic foodborne disease

25. Case-Control Studies of Sporadic Foodborne Disease • Hazard identification • Attribution to food • Association of specific food-pathogen combinations • If population-based, studies provide rates that can be generalized

26. FoodNet Case Control Studies • Salmonella • Campylobacter • E. coli O157 • Cryptosporidium • Listeria • Infant illness: (Salmonella, Campylobacter) • Salmonella Newport • Salmonella Enteritidis

27. Improving Surveillance for Foodborne Disease Surveillance Outbreak Detection Algorithm (SODA) • PC-based program for detecting Salmonella and Shigella outbreaks Electronic Foodborne Outbreak Reporting System (EFORS) • Web-based system for reporting foodborne disease outbreaks DPDx • Parasitic diagnostic support for states by videoconference PulseNet • National network of laboratories for molecular fingerprinting of foodborne pathogens for rapid comparison of “fingerprints” with central database • Enhances detection of common source outbreaks, especially geographically dispersed outbreaks Calicinet • Enhanced viral diagnostics and subtyping

28. PulseNet USA • National network of laboratories for molecular fingerprinting of foodborne pathogens • All 50 states, CDC, FDA, and FSIS • Plans to add additional USDA laboratories and possibly academic and industry laboratories • Standardized protocols allows rapid comparison of digital images of fingerprints with central data base • Enhances detection of common-source outbreaks, especially multistate outbreaks

29. PulseNet Expansion • Geographic Expansion • PulseNet Canada • PulseNet Europe • PulseNet Asia Pacific • PulseNet Latin America (2004) • Microbial Expansion • Methodological Expansion

30. PulseNet Expansion • Geographic Expansion • Microbial Expansion • Current: E. coli O157, Salmonella, Listeria, Shigella, Campylobacter • Future: Non-O157 STEC, Vibrio cholerae, Yersinia enterocolitica, V. parahaemolyticus, Clostridium perfringens • Methodologic Expansion • Current: Rapid standardized PFGE protocols • Future: MLVA, MLST, Microarrays, other

31. Epidemiology and Risk Assessment • Incidence of diseases that may be foodborne • Proportion of these diseases that are foodborne • Major food vehicles of transmission • Characterization of conditions under which foodborne transmission occurs

32. Characterization of Conditions of Foodborne Transmission • Frequency and level of contamination • Dose-response relationship • Important antecedent factors

33. Qualitative Food Microbiology Data NFPA/JIFSAN Retail Study

34. Quantitative Food Microbiology Data Of 9,199 deli meat samples, 82 (0.9%) were Lm positive • 42 samples 0.04 – 0.1 cfu/g • 20 samples >0.1 –1 cfu/g • 10 samples >1-10 cfu/g • 2 samples 10-100 cfu/g • 7 samples 100-1000 cfu/g • 1 sample 103 to 104 cfu/g 77% of the RTE meat samples were pre-packaged by the manufacturer -- 0.4% were Lm positive 23% of the RTE meat samples were deli-packed -- 2.7% were Lm positive NFPA/JIFSAN Retail Study

35. Exposure Assessment Frequency of food contamination at retail Number of Lm in contaminated samples Storage time and temperature in home Lm growth potential in foods Log reduction in reheated franks Amount consumed/serving Number of Lm consumed per serving

36. Exposure Assessment: Other Factors to Consider • Home refrigerator temperatures • Percent of frankfurters reheated • Effect of temperature on growth rate • Effect of temperature on extent of growth

37. Hazard Characterization: probabilityof illness and death as a function of number of L. monocytogenes ingested • Dose-response curve from mouse studies • Area under the curve set by FoodNet data on human listeriosis • Other factors: • Variation in virulence of L. monocytogenes isolates • Variation in susceptibility within age groups • Variation in susceptibility between age groups • Variation in fatality to hospitalization ratio

38. Dose of Listeria and Mortality in Mice

39. Human Listeriosis Cases to be Distributed within the Mouse Dose-Response Curve Sub- FoodNet Reported National Projected Population Listeriosis in 4 Years Annual Listeriosis _________ CasesDeathsCasesDeaths Neonatal 38 3 216 16 Elderly 194 52 1159 307 Other 113 10 701 67 Total 345 65 2078* 390 Neonatal cases were multiplied by 2.5 to account for under-ascertainment, giving a case total for all listeriosis of 2400 for purposes of analysis.

40. Current Foodborne Disease Epidemiology • Documents that too much food-related illness and death occurs • Poorly characterizes the diseases • Complicates risk ranking and priority setting • Biased toward traditional bacterial enteric pathogens and foods of animal origin

41. Enhanced Foodborne Disease Epidemiology • Improved health outcome data • Better diagnostics and subtyping • Enhanced epidemiologic follow-up • More quantitative data • Improved food chain information • Surveillance based on food microbiology • Linkage of in-line indicators with health outcomes • Improved risk assessments