Foodborne Outbreaks in California: Detection, Etiology, Recent Trends, Investigation

1. Foodborne Outbreaks in California: Detection, Etiology, Recent Trends, Investigation Janet Mohle-Boetani, MD, MPH Chief, Infectious Diseases Branch California Dept. of Health Services

2. Outline Detection of Outbreaks local vs. state detection Investigation of Outbreaks- roles in CA single event/single location vs. widespread Outbreak control and prevention local control vs. statewide/national prevention Major Etiologic Agents Trends in Foodborne Outbreaks Investigation Steps and Homework

3. Detection of Outbreaks by LHDs Telephone call by resident/institution/physician about cluster of persons with similar symptoms vomiting among persons who had been at a common event (eg, party) or location (eg,restaurant/camp) review of logs of individual complaints: common location detected (works with short incubation) Routine interviews by local HD with patients diagnosed with bacterial infections (eg, Salmonella, E. coli O157 or Shigella) reveals an eating event/location in common

4. Detection by LHD (cont.) Residential facilities health care facilities (hospitals and skilled nursing facilities) report to both local HD and L&C department of social services facilites (retirement communities, assisted living center, group homes) report to LHD prisons and jails report to local HD State notifies local HD about a cluster of patients with the same unusual strain of Salmonella or E. coli O157

5. Detection of Outbreaks by CDHS Lab Detection Microbial Diseases Laboratory notifies Infectious Diseases Branch (IDB) in DHS about a cluster of cases of infection with an unusual strain of bacteria (eg, E. coli O157 or Salmonella) detected through serotyping or DNA fingerprinting (resource issue) FoodNet/PulseNet (Centers for Disease Control and Prevention) notifies IDB about California cases linked to those in other states by DNA fingerprinting of isolates

6. Roles: Local Health Agencies Communicable Disease Control unit usually in the Health Department Environmental Health unit MAY be in the Health Department or may be in a separate department Local Public Health Laboratory- usually in the Health Department

7. Roles: Local Outbreaks Epidemiologic: to determine etiologic agent, food vehicle, and if foodhandlers are infected Interviews with cases: symptoms/incubation period Case-control or cohort study among attendees of an event or patrons of a restaurant Interviews with foodhandlers re: illness Environmental: to determine important contributing factors and obtain specimens General inspection Specific investigation Hazard Analysis and Critical Control Point evaluation on food vehicle implicated in epidemiologic study Collect food or environmental specimens Laboratory Human, food, and environmental specimens

8. Roles: State/Federal Agencies California Department of Health Services Infectious Diseases branch (IDB), Microbial Diseases Laboratory (MDL), and Viral and Rickettsial Diseases Laboratory (VRDL) in the Division of Communicable Disease Control Food and Drug branch (FDB) in the Division of Food, Drug and Radiation Safety California Department of Food and Agriculture Federal Food and Drug Administration (FDA) US Department of Agriculture (USDA)

9. Roles: Widespread Outbreaks Epidemiology: LHD collects descriptive information (morbidity/mortality), IDB in CDHS conducts case-control study to determine food vehicle. Food and Drug Branch (FDB) in CDHS/FDA conducts traceback and environmental investigation if eggs, produce or commercial products. Environmental investigation on egg ranches NOT in CEQUAP California Dept of Food and Agriculture/USDA conducts traceback and environmental investigation if dairy or meat. Environmental investigation on egg ranches in CA Egg Quality Assurance Program CDHS/CDFA work with industry to prevent future outbreaks (eg, interventions with sprout growers and egg ranches)

10. Major types of Foodborne Outbreaks

11. Common Causes of Foodborne Outbreaks

12. Staphylococcal Foodpoisoning Heat stable toxin from S. Aureus Infected workers (skin, eye, nose)- boils, sinus infections, even common cold Food- good growth medium and held at improper temperature for hours Prevent- exclude workers with purulent discharges, colds, and cover skin lesions

13. Clostridium perfringens Foodpoisoning Incubation 12 hours, short duration diarrhea, rarely need MD CP is ubiquitous in soil and GI tract of man and animals Not usually lab confirmed- new PCR test Food- storage of meats/stews in huge quantity at room temp or slow cooling, insufficient reheating Prevent- eat after initial cooking or cool rapidly, serve cold or rewarm to 165 ASAP

14. Salmonella Zoonotic infection, >2000 serotypes Diarrhea, fever, 12 hr- 7 day incubation, prolonged symptoms (several days), often seek medical help Foodborne transmission- infected/contaminated raw meat or food contaminated in field/distribution chain foodhandler transmission is rare Traditionally meat/poutry but now many outbreaks due to raw produce Prevention- cook food well, wash produce?, decrease contamination: on farm? in distribution chain? in meat processors? in fresh cut product plants?

15. Norovirus Infections Symptoms: vomiting, diarrhea, fever, myalgia Incubation period: 36 hours (24-48 hrs) Symptom duration: 1-2 days Definition of �Suspected Norovirus Outbreak� >50% vomiting Incubation close to 36 hours No bacterial pathogens found Secondary transmission Human pathogen solely: no zoonotic spread-THINK ILL FOODHANDLER Prevention- exclude foodhandlers with vomiting or diarrhea

16. Other Important Foodborne Illnesses Botulism (C. botulinum)- cranial nerve palsies- droopy eyelids, double/blurry vision Improperly canned food, also refrigerated pre-cooked foods not reheated (clam chower) Bacillus cereus poisoning- like SA (heat stable toxin) or CP (heat labile toxin) Scombroid fish poisoning- Spoiled fish in the tuna family �Allergic� symptoms: flushed skin, hives, itching, rash, facial swelling

17. Foodborne Disease Outbreaks in California: Recent Trends in Etiologic Agents

18. Definitions Foodborne Disease Outbreak: 2 or more cases of a similar illness resulting from the ingestion of a common food. Confirmed: CDC definitions (> 2 lab cases but only 1 for C. bot and norovirus until 2004) Suspected: based on symptoms, incubation period, duration (e.g., norovirus)

19. Data Form 52.13 �Investigation of a Foodborne Outbreak� LHDs fill out and send to State State fills out (e.g., if multicounty outbreak) Review Confirmed etiologic agent? Suspected etiologic agent? Confirmed food vehicle? Ill foodhandler?

20. Foodborne Outbreaks by Yearand Confirmation Status

21. Confirmed Etiologic Agents

22. Confirmed Etiologic Agent Category by Year

23. Confirmed Agents Causing Foodborne Outbreaks, California

24. Confirmed Etiologic Agent Category by Year

25. Norovirus Outbreaks by Yearand Confirmation Status

26. Foodborne Disease Outbreaks: Trends in Food Vehicles, California

27. Definitions Confirmed food vehicle: Isolation of agent from a food Epi investigation with a stat sig association Categories of food vehicles: Produce, meat/poultry, dairy, egg, seafood Multiple, other

28. Food Vehicle by Year of OutbreakCalifornia

29. Proportion of Outbreaks by Food Vehicle and 5- Year Period

30. Notable outbreaks S. Thompson and cilantro S. Enteritidis and mung bean sprouts S. Enteritidis and almonds S. Poona and imported cantaloupes S. Typhimurium and Mexican style cheese E. coli O157 and ground beef tacos E. coli O157 and prepacked/washed lettuce/spinach

31. Summary Local Health Departments usually identify and investigate single event/location foodborne outbreaks State usually identifies and investigates widespread/multicounty foodborne outbreaaks Increased detection of outbreaks due to Norovirus; most of these are due to infected foodhandlers Increased detection of outbreaks due to produce

32. Outbreak Investigations

33. Steps 1 and 2: Outbreak Exists and Confirmation 1)Existence of an outbreak Example- Salmonella Saphra outbreak Example- vomiting and diarrhea among patrons of a restaurant about 36 hours after eating Event vs. non-event 2A)Determine Likely agent/ Confirm Dx Symptoms, incubation period, transmission Standard lab techniques: culture, serology DNA fingerprinting for common serotypes (eg, SE)

34. Step 3: Define and Count Cases 3A)Define cases: practical, reliable, apply without bias Example: E. coli O157 at Restaurant X Confirmed: culture positive with same PFGE pattern and ate at restaurant X during Y time frame Probable: bloody diarrhea and ate at restaurant X during Y time frame Possible: diarrhea (3 loose stools per day) and ate at restaurant X during Y time frame

35. Step 3: Continued Case Definition may need to be updated within an investigation Broad to specific Infection with E. coli O157 vs. infection with the outbreak strain (defined by PFGE pattern) Setting may change Restaurant associated outbreak may broaden to sporadic cases based on laboratory analysis

36. Step 3: Continued 3B) Count Cases Case Finding: encourage testing Stools for norovirus can be collected up to 1 week after onset Collect: Demographics (age, sex, race, residence, occupation) Symptoms and date of onset Laboratory data Isolates for further testing (eg, DNA fingerprinting)

37. Step 4: Orient the Data 4A)Orient data by time (epi curve: # cases [Y axis] vs. onset date[X axis]) Point source outbreak: mean onset date minus incubation period= exposure date Example: textbook Ongoing transmission Example: shigellosis in Lexington Control of outbreak Example: Salmonella outbreak

39. Step 4: Orient the Data 4A)Orient data by time (epi curve: # cases [Y axis] vs. onset date[X axis]) Point source outbreak: mean onset date minus incubation period= exposure date Example: textbook Ongoing transmission Example: shigellosis in Lexington Control of outbreak Example: Salmonella outbreak

41. Step 4: Orient the Data 4A)Orient data by time (epi curve: # cases [Y axis] vs. onset date[X axis]) Point source outbreak: mean onset date minus incubation period= exposure date Example: textbook Ongoing transmission Example: shigellosis in Lexington Control of outbreak Example: Salmonella outbreak

42. S. Senftenberg Outbreak, 1997-1998

43. Step 4: Orient the Data 4B)Orient data by place: location in city, hospital, prison Example: TB in a prison Example: E. coli O157 and sprouts

45. Step 4: Orient the Data 4C)Orient data by person: age-group Example: Salmonella and marijuana Sex Example: Salmonella and alfalfa sprouts Ethnicity Example: Salmonella and cheese

46. Step 5: Determine who is at risk 5)Determine who is at risk: Example: Salmonella and Obon Festival Example: E. coli O157 and restaurant chain and schools (same produce supplier) 5B) �Outliers� may provide key information Example: E. coli O157 and school lunch Example: E. coli O157 in residents outside of SLO traveled to SLO

47. Step 6: Hypothesis Generation 6A)Generate Hypotheses Indepth interviews: Example: foodborne outbreak in restaurant: use menu, hypothesis generation with 5-10 patients: garnishes (not on menu) or Example: foodborne outbreak multicounty: >70 food item questionnaire and open-ended Usually generates an outbreak specific profile Examples: deli restaurants, Mexican restaurants, spring break in NY/Chicago/Europe

48. Epidemiologic Investigation Goal 1: Identify a specific food item associated with disease Goal 2: Prevent future disease recall contaminated product determine how the product was contaminated and develop guidelines to prevent contamination in the future

49. Homework Exercise

50. Food-borne Outbreak Investigation Steps- I

51. Food-borne Outbreak Investigation Steps- II

52. Food-borne Outbreak Investigation Steps- III

53. Food-borne Outbreak Investigation Steps- IV

54. Format for Reporting: Cohort Study

55. Format for Reporting: Case-Control Study