Foodborne Infections: How Outbreak Investigations Improve the Public Health

1. Foodborne Infections: How Outbreak Investigations Improve the Public Health 6th Food Safety Forum North Carolina Department of Agriculture and Consumer Services August 10, 2010 Raleigh, NC Robert V. Tauxe, M.D., M.P.H. Deputy Director, Division of Foodborne, Waterborne, and Environmental Diseases National Center for Emerging and Zoonotic Infectious Diseases Centers for Disease Control and Prevention

2. Foodborne disease - 2010 a continuing public health concern • Common: • ~1,200 foodborne outbreaks reported each year • Most reported cases are "sporadic“ • Tens of millions made ill each year, and thousands die • Complex: • Many different pathogens and toxins • Wide variety of foods • Continuing: • Some progress, less in recent years • New problems need new strategies for prevention • Dispersed outbreaks challenge the food safety system • and show us how to improve it

3. Many different pathogens and toxins • More than 250 pathogens and toxins transmitted by food • More pathogens continue to be identified • Many spread via food, water, direct animal or human contact • The 6 most important pathogens Mead, EID 1999 *And other Shiga toxin-producing E. coli

4. Many types of foods are implicated in outbreaks • 2003-2007: Illnesses in 1,355 outbreaks caused by single food Mollusk Grains-Beans Eggs Poultry Other Finfish Pork Leafy greens Vine Beef Fruits-Nuts Dairy National Foodborne Outbreak Surveillance System

5. Large outbreaks highlight gaps in our food safety system • President’s Food Safety Working Group is coordinating improvements in prevention across the different federal agencies that are part of the food safety system • Many recent and current efforts to improve safety of food supply in specific ways • Now setting Healthy People 2020 Goals for reduction in incidence of specific foodborne infections Presidents Food Safety Working Group, Healthy People 2020 Goals

6. CDC Non-regulatory National disease surveillance Outbreak detection and investigation to determine vehicle and source Tracks burden and trends Tools and training for local and state public health agencies Problem identification Provide information to guide regulatory action USDA/FSIS: Meat & poultry FDA: other foods Regulatory Food safety policies Inspect, monitor, enforce Product recall and traceback Investigation of farm and production facilities Tools and training for regulatory partners Source assessment Risk management Federal agency roles and responsibilities

7. The systematic ongoing collection, analysis and dissemination of information about health conditions in a defined population to guide public health action Public health surveillance • Define the current magnitude and burden of a disease • Identify outbreaks • Inform priorities for prevention and control • Measure the impact of control and prevention efforts

8. Trends in foodborne diseases,FoodNet,1996-2009 Since 1996-98, significant drops in: E. coli O157 – 41% Campylobacter – 30% Listeria -- 26% Salmonella – 10% Significant increase in Vibrio + 85% In last 4 years, significant drop in: E. coli O157- 25% MMWR 2010; 59:418-422 (April 16, 2010)

9. Outbreak investigations are a major driver for enhancing overall food safety • Prevent additional cases in the current outbreak • Determine what went wrong in order to prevent future similar outbreaks • Define high risk foods and gaps in the system • May find a new pathogen or problem • Stimulate further research • Stimulate new processes and regulations

10. Stages in a foodborne outbreak investigation • Detection: “Is something unusual happening? To whom?” • Developing hypotheses: “What foods or other exposures could be involved?” • Testing the hypotheses: “Which food is associated with illness?” • Traceback and environmental assessment: “Where did that food come from, and what happened to it along the way?” • Control: “Is the contaminated food no longer available? • Long term prevention: “What needs to change to keep something like this from happening again?”

11. Epidemiologists to interview the ill and healthy people Microbiologists to test human and food specimens, and “fingerprint” the strains Environmental Health specialists to assess food preparation and environment Experts in distribution and processing Communicators to share information with public Regulatory authorities to take necessary control measures Investigating foodborne outbreaks takes a team

12. A large outbreak in one place may be obvious Local surveillance will detect this event

13. An outbreak with cases dispersed in many places is difficult to detect, unless • We test bacteria from all the cases, and • We find they are infected with the same bacterial strain, and different from other similar illnesses • We find on interview they shared an exposure

16. State laboratory coordination in PulseNet PFGE patterns Public health laboratories National database

17. PFGE patterns uploaded to PulseNet databases, by year, 1996-2009 Bacteria: Mainly E. coli O157, Listeria monocytogenes, Salmonella Coming soon: CaliciNet, CryptoNet, and HepAVirusNet

18. Average number* of clusters followed by CDC, by month and pathogen, February, 2008 – April, 2010 2009 average weekly number of clusters followed = 29 (range: 16-41) 2008 weekly average number of clusters followed = 24 (range: 10-37) * Number per week averaged over a month period

19. Focal outbreak Large number of cases in one jurisdiction Detected by affected group themselves Local investigation Local food handling error Local solution The spectrum of foodborne disease outbreaks • Dispersed outbreak • Small numbers of cases in many jurisdictions • Detected by lab-based subtype surveillance • Multi-state investigation • Industrial contamination event • Broad implications

20. Salmonella Typhimurium infections and peanut butter containing products – 2008-2009 Investigation began in Nov 2008 of a cluster of 35 cases in 16 states As of March 17, 691 cases 46 states, 23% hospitalized 9 deaths Median 16 days time lag between onset of illness and upload to PulseNet MMWR 2009: vol 58, p 85-90, Feb 5

21. Salmonella Typhimurium infections and peanut butter containing products – 2008-2009 MMMWR 2009: vol 58, p 85-90, Feb 5 Findings preliminary and may change

22. Salmonella Typhimurium infections and peanut butter containing products – Prevention lessons learned • Institutional brand of peanut butter was first food vehicle implicated • Same company produced peanut paste, an ingredient in many other implicated products: crackers, pet treats, and roasted peanuts used to make PB ground in the store • Conditions in plant suboptimal (rainwater, mixing raw and cooked peanuts) • Then current inspection practices did not identify problems before the outbreak, nor did third party audits • Communication challenges around recalling huge number of products, and later re-introducing them

23. Salmonella Typhimurium infections and peanut butter containing products – Process lessons learned • A highly dispersed outbreak • Likely not identified without PulseNet • No large focal clusters • Detailed local case investigations critical • Foods in common to institutions with cases • First vehicle identified did not explain some cases – continue to consider more hypotheses • Ongoing case investigations linked with observations in plant investigation – identified other implicated products • Investigative challenges • “Generic” vehicle: peanut butter served in cafeterias • “Ingredient-driven” outbreak – 3,900 products recalled • “Long-tailed” outbreak – products with long shelf lives

24. 2006 - E. coli O157 and bagged spinach 2006 - E. coli O157 and shredded lettuce (restaurant chain A) 2006 - E. coli O157 and shredded lettuce (restaurant chain B) 2006 - Botulism and commercial pasteurized carrot juice 2006 - Salmonella and fresh tomatoes 2007 - E. coli O157 and frozen pizza 2007 - Salmonella and peanut butter 2007 - Salmonella and a vegetarian snack food 2007 - Salmonella and dry dog food 2007 - Salmonella and microwaveable pot pies 2007 - Salmonella and dry puffed rice breakfast cereal 2007 - E. coli O157 and ground beef 2007 - Botulism and canned chili sauce 2008 - Salmonella and cantaloupe 2008 - E. coli O157 and ground beef 2008 - Salmonella and fresh produce items 2009 - Salmonella and peanut butter containing foods 2009 - Salmonella and imported white pepper 2009 - Salmonella and alfalfa sprouts 2009 - E. coli O157 and prepackaged cookie dough 2009 - Multi-drug resistant Salmonella and ground beef (x2) 2009 - E. coli O157 and blade tenderized steaks 2009 - Salmonella and black pepper crusted salami 2010 - E. coli O145 and romaine lettuce 2010 - Salmonella and alfalfa sprouts 2010 - Salmonella and frozen meats Some recent large multi-state outbreaks of foodborne infections 2006-2010 (n = 26)

25. Some recent large multi-state outbreaks of foodborne infections 2006-2010 (n=26) 2006 - E. coli O157 and bagged spinach * 2006 - E. coli O157 and shredded lettuce (restaurant chain A) 2006 - E. coli O157 and shredded lettuce (restaurant chain B) 2006 - Botulism and commercial pasteurized carrot juice * 2006 - Salmonella and fresh tomatoes 2007 - E. coli O157 and frozen pizza 2007 - Salmonella and peanut butter * 2007 - Salmonella and a vegetarian snack food * 2007 - Salmonella and dry dog food * 2007 - Salmonella and microwaveable pot pies * 2007 - Salmonella and dry puffed rice breakfast cereal * 2007 - E. coli O157 and ground beef 2007 - Botulism and canned chili sauce * 2008 - Salmonella and cantaloupe 2008 - E. coli O157 and ground beef 2008 - Salmonella and fresh produce items * 2009 - Salmonella and peanut butter containing foods 2009 - Salmonella and imported white pepper * 2009 - Salmonella and alfalfa sprouts 2009 - E. coli O157 and prepackaged cookie dough * 2009 - Multi-drug resistant Salmonella and ground beef (x2) 2009 - E. coli O157 and blade tenderized steaks 2009 - Salmonella and black pepper crusted salami * 2010 - E. coli O145 and romaine lettuce 2010 - Salmonella and alfalfa sprouts 2010 - Salmonella and frozen meals * • A new food vehicle in 13/26 outbreaks

26. Better surveillance means we detect some we would have missed before Centralized production of foods means when a problem occurs it may be widespread More imported foods and food ingredients, depending on food safety systems in other countries Gaps in our own food safety system: Technologies adopted without validation Limited capacity for inspection and enforcement Need to understand ecologies that lead to contamination Why are we seeing all these multi-state foodborne outbreaks?

27. Detected with molecular subtype-based national surveillance Epidemiological investigation  control actions (food recalls) often before pathogen isolated from product An opportunity to learn more about a new or ongoing issue Ground beef Shiga toxin producing E. coli (especially E. coli O157) Multi-drug resistant Salmonella Fresh vegetables Leafy greens, tomatoes, peppers, sprouts Easily contaminated in field Complex ecologies link pastures, streams, and vegetable fields Processed foods contaminated in factory Spices, peanut butter, dog food kibble, pot pies, frozen pizza Sanitation issues in food factories Better strategies for prevention and inspection Lessons from recent multistate outbreaks

28. Time: The clock is ticking, and we depend on human memory Distance: Many people in many jurisdictions need to be asked the same questions, and the results rapidly pooled Numbers: many clusters, limited resources “Stealth foods”: Foods/ingredients we don’t remember eating Distribution: Can be hard to trace a food to its source Investigations take time and depend critically on local and state health department capacity to investigate cases detect clusters network with other jurisdictions Challenges of the dispersed outbreaks

30. Improving our public health system for surveillance and investigation • Speed of PulseNet • Salmonella: 18 days from onset of illness to PulseNet • Resources at state and local health departments to conduct interviews: • “Sporadic” illnesses (some may later be shown to be part of outbreaks) • Interviews to probe possible sources may be delayed by other priorities • Re-interviews to collect product information may be delayed • Questionnaires often not standardized among states, nor is information easily added to a central database Contrast with PulseNet, in which lab information on every isolate is stored in a standard database at States, is rapidly transmitted to a national database at CDC, and summary information is available to all participants

31. A “winnable battle” to improve food safety through better surveillance and investigations • Improving outbreak response, with new and enhanced tools, methods and processes • Empowering our partners in prevention with information about the burden of foodborne illnesses and attribution of foods to specific food commodities • Supporting local, state and federal capacity for surveillance and response • Working with international partners to improve efforts in many countries, identify problems before they reach us, and make food safer everywhere

32. Improving foodborne outbreak investigation and coordination • Improve methods and build capacity • 2009: Guidelines by Council to Improve Foodborne Outbreak Response (CIFOR) (a multiagency group) • 2010: New CDC initiative: OutbreakNet Sentinel Sites • Modeled on success of PulseNet, applying standardized and innovative methods in up to four sites

33. OutbreakNet Sentinel Sites: Starting in 2010 • New network for developing and assessing methods • Improve public health methods for foodborne outbreak detection, investigation and control • Faster interview and other investigative methods • Faster and newer laboratory procedures • Standardized approaches • “Investigate more outbreaks faster” • Develop infrastructure to collaboratively share and work on data in real time during multi-state outbreak investigations • Replicate successful models across the country

34. Foodborne diseases will be a major public health problem • Expect new pathogens, new foods in new combinations • Animal reservoirs • Fresh produce • Processed foods • More multi-jurisdictional outbreaks • Multi-county, multi-state, multi-continent • Prevention includes critical attention to settings in which we raise animals and plants • Robust public health capacity for surveillance and response to foodborne infections a critical part of food safety system Foodborne diseases in the 21st century

35. Thank you The findings and conclusions in this presentation are those of the author and do not necessarily represent the views of the Centers for Disease Control and Prevention

36. The fall and rise of reported Salmonella infections in the United States, 1920-2007 CDC, National surveillance data