1. FDA/NSTA Web Seminar: Food Safety and Nutrition LIVE INTERACTIVE LEARNING @ YOUR DESKTOP Thursday, April 26, 2007 7:00 p.m. to 8:00 p.m. Eastern time

2. Outbreak Investigation Surveillance and Epidemiology “Be the Detective” Foodborne Illness Outbreak Investigation Surveillance and Epidemiology “Be the Detective” Patrick McCarthy, PhD, MPH Food & Drug Administration U.S. Dept of Health and Human Services

3. USDA Food Safety and Inspection Service –Responsible for ensuring safety of meat, poultry, and some egg products

4. US Food & Drug Administration Responsible for ensuring safety of all other food products

5. based on surveillance data Estimates of foodborne illness and death based on surveillance data 325,000 hospitalizations each year 5,000 deaths each year 14 million illnesses due to known pathogens 62 million illnesses due to unknown pathogens Paul Mead-CDC-1999

6. Factors Pushing the Numbers Up Globalization of the food supply Perceived healthiness of raw fruits and vegetables Increase in susceptible population Eating out more International travel D Swerdlow, S Altekruse 1998

7. Which agency regulates these products: Type a “U” for USDA, or an “F” for FDA VegetablesMeatSpicesSeafood ChickenDiet supplements Infant formulaPizza with a lot of meat

8. Why do we do surveillance? Identify emerging problems and stimulate actions to address them Take prompt control actions Identify and interpret trends in foodborne disease Determine the consequences of foodborne illness Evaluate intervention programs Set goals, priorities, policies, training, etc. for food safety

9. How is foodborne illness recognized? From patients or someone close to patients Report from MD, RN, laboratory, etc. Review of national surveillance data – Salmonella Outbreak Detection Algorithm (SODA) – PulseNet – FoodNet Rarely: local newspaper or television news report

10. Percentage of Foodborne Illness Attributable to Known Pathogens Mead et al., 1999

11. Identify what you think is the best reason to have a foodborne illness surveillance program? 1. 2. 3.

12. Foodborne Outbreaks - FDA products only YearProduceSproutsDairyEggsProc. foods Seafood Cosmetics Total 199622034426068 19974313218049 19986302516041 19999603038056 20005112856046 200183316113044 20026242113037 20036541536039 20041026259135 2005703446226 Total63272220728913441

13. Why investigate outbreaks? Identify and eliminate sources of exposure Develop strategies to prevent future outbreaks Describe new diseases Learn more about existing diseases Evaluate existing prevention strategies

14. Why does it take so long?

15. Reported to health department Culture-confirmed case Lab tests for organism Specimen obtained Person seeks care Person becomes ill Population exposures Determining Burden of Disease

16. Did you ever have a foodborne illness? Yes (  ) No (X)

17. If you answered yes to the previous poll question, did you report the illness to the health department? Yes (  ) No (X)

18. Multiplication Factors For Salmonella and other pathogens that cause non-bloody diarrhea the degree of underreporting has been estimated at about 38 fold. For EC0157H7 and Shigella which cause bloody diarrhea - underreporting has been estimated at about 20 fold. P Mead – CDC 1999

19. Burden of Illness

20. Measuring the Association Between Exposure and Disease Attach Rate Table – Cohort Study Food Exposure Ate Food - Yes Total Ill % Ill Ate Food - No Total Ill % Ill Association RR 95% CI Oysters19 12 63% 20 14 70% 0.9 0.58 -1.41 Salad28 24 86% 11 2 18% 4.7 1.33 -16.8 Baked Ham 22 16 73% 17 10 59% 1.2 0.77 -1.98

21. Cohort study: relative risk illnot ill Exposed24 4 Unexposed2 9 At start of cohort study you know everyone’s exposure status total exposed = 28; total unexposed = 11 go forward in time and determine risk of getting ill risk if exposed = 24 / 28 = 0.857 risk if not exposed = 2 / 11 = 0.182 Relative Risk = 0.85 / 0.18 = 4.71 28 11 total

22. http://www-unix.oit.umass.edu/~exsc597j/Epi2000/ENGLISH/HELP/statist.htm

23. Take Home Message In cohort studies the relative risk (RR) compares rate of illness in the exposed group to rate of illness in the unexposed group. In case-control studies the odds ratio (OR) is the odds in favor of exposure among cases compared to the odds in favor of exposure among the controls. if RR or OR = 1, or the 95 % CI includes 1 then the result is not considered statistically significant If RR or OR is less than 1 may mean food item is "protective“

24. Review: What pathogen is associated with the most foodborne illness ? BacteriaProtozoaViruses

25. Traceback Track food items back to their source (product type, lot #, delivery time, etc.)

26. Traceback - protocol Traceback protocol includes –extensive record reviews –extensive interviews –records / information collected includes shipments, inventories, transportation, etc. –data analyses

27. Traceback - case study Details: –AZ; 19-ill; church group, restaurant, July 5 th –NV; 12-ill; friends, restaurant, July 8 th –CA; 14-ill; party, restaurant supplied food, July 9 th lab reports all cases have identical PFGE pattern case-control study is conducted spinach is implicated traceback is initiated to determine source of the spinach

28. Scenario - common farm Restaurant B San Diego, CA Spinach Distributor A Denver, CO Restaurant C Las Vegas, NV Restaurant A Phoenix, AZ Farm A Nogales, AZ Farm B Salinas, CA Farm C Tucson, AZ No common restaurant so distributors can be eliminated as a possible contamination source. Spinach Distributor B Salinas, CA Farm B supplies both distributors and is suspected contamination source.

30. Product Contamination 4 important sources –soil –water –farm workers –domestic and feral animals

31. Outbreak of Escherichia coli O157 Infections Associated with Fresh Spinach August-September 2006 Early epi information –3 possible processors in California –dozens of possible ranches Possible ongoing exposures so FDA advises consumers not to consume bagged spinach Actions taken by other countries based on early information.

32. Question: Type your answers on the chat window Can you identify potential sources of produce contamination in addition to these: –soil –water –farm workers –domestic and feral animals

33. E. Coli O157:H7 and Spinach Sept. 14 th ; FDA notified of multi-state investigation possibly linked to bagged spinach - possible ongoing exposures - early epi could not identify a firm or lot code Sept. 14 th ; California Food Emergency Response Team dispatched to three firms Sept. 14 th ; phone calls between CDHS, FDA, and implicated firms begin Sept. 15 th ; firm X initiated a voluntary recall

34. AugustSeptember Date of initial symptom onset Number Of Cases by Date of Illness Onset United States, August-September, 2006 August 15, 2006 Lot -227 production date All data is preliminary

35. Baby Spinach Harvesting

36. Results: –E.coli O157:H7 found on 4 ranches –9 isolates, from 1 ranch were PFGE indistinguishable from outbreak strain (1 stream, 1 pig feces, 7 cow feces) ranch is primarily a beef cattle operation a stream on the property - ideal habitat for wildlife – feral pigs, etc. well is shallow and sits in a slight depression in the field.

37. Produce Outbreaks some lessons learned Leafy vegetables have elevated levels of bacteria due to large surface areaLeafy vegetables have elevated levels of bacteria due to large surface area Bacteria tends to adhere and accumulate in structures and at cut surfaces - once internalized, pathogens are difficult to removeBacteria tends to adhere and accumulate in structures and at cut surfaces - once internalized, pathogens are difficult to remove Pathogen survival varies greatly Negative lab result ≠ absence of pathogen

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41. National Science Teachers Association Gerry Wheeler, Executive Director Frank Owens, Associate Executive Director Conferences and Programs Al Byers, Assistant Executive Director e-Learning LIVE INTERACTIVE LEARNING @ YOUR DESKTOP NSTA Web Seminars Flavio Mendez, Program Manager Jeff Layman, Technical Coordinator Susan Hurstcalderone, Volunteer Chat Moderator