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

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

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

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

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

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

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

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

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

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

Identify what you think is the best reason to have a foodborne illness surveillance program?

Foodborne Outbreaks - FDA products only YearProduceSproutsDairyEggsProc. foods Seafood Cosmetics Total Total

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

Why does it take so long?

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

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

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

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

Burden of Illness

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 Oysters % % Salad % % Baked Ham % %

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 = risk if not exposed = 2 / 11 = Relative Risk = 0.85 / 0.18 = total

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“

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

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

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

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

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.

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

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.

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

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

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

Baby Spinach Harvesting

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.

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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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 YOUR DESKTOP NSTA Web Seminars Flavio Mendez, Program Manager Jeff Layman, Technical Coordinator Susan Hurstcalderone, Volunteer Chat Moderator