Defense Research Institute<br />Making the Causal Link:  Investigating Foodborne Disease OutbreaksWilliam D. Marler, Esq.<...
CDC Estimates of Foodborne Illness<br />48 million cases of foodborne illness annually<br />125,000 hospitalizations<br />...
Estimates Differ From Actual Counts <br />Annual E. coli O157 estimates<br />62,000 illnesses<br />1,800 hospitalizations<...
Notifiable/Reportable Diseases<br />Reporting authorized by Congress in 1878<br />Nationally Reportable Diseases(food or w...
Pathway of a Foodborne Illness Investigation<br />Health Care Provider      <br />Ill person<br />Specimen collection<br /...
Pathway of a Foodborne Illness Investigation<br />Health Care Provider      <br />Ill person<br />Specimen collection<br /...
How Do We Know If There Is an Excess?<br />Public Health Surveillance<br />The ongoing collection, analysis, interpretatio...
Pathway of a Foodborne Illness Investigation<br />Health Care Provider      <br />Ill person<br />Specimen collection<br /...
Typical Steps of an Outbreak Investigation<br />Establish that an outbreak is occurring<br />Verify the diagnosis<br />Def...
A Word to the Wise!<br />No mandatory list of how to proceed<br />No set order of steps to take<br />Investigation is dyna...
Investigative Partners<br />Laboratory investigators<br />Microbiologic diagnosis<br />Virology/Parasitic Labs<br />Molecu...
Epidemiology–Basic Tools of the Trade<br />Real-time interviewing with a broad-based exposure questionnaire<br />Symptoms<...
Pulsed Field Gel Electrophoresis (PFGE)<br />A Powerful Outbreak Detection Tool <br />Process separates chromosomal fragme...
Questions to Consider in Assessing PFGE Clusters<br />How common is thePFGE subtype?<br />How many cases are there?<br />O...
E. coli O157:H7 Outbreak, Minnesota, September 2005<br />Thanks to MN DOH for use of the following slides!<br />Team Diarr...
Outbreak Detection<br />September 27, 2005<br /><ul><li>Three O157 isolates with indistinguishable PFGE patterns identifie...
PFGE pattern new in Minnesota, rare in United States
0.35% of patterns in National Database
Patients reported eating prepackaged salad; no other potential common exposures evident</li></li></ul><li>7<br />6<br />5<...
Outbreak Investigation - Methods<br />September 28–29, 2005<br />Additional O157 isolates received at the MDOH and subtype...
7<br />6<br />5<br />Number of Cases<br />4<br />3<br />2<br />1<br />15<br />16<br />17<br />18<br />19<br />20<br />21<b...
Case-Control Study Results<br />Cases<br />Exposure<br />Controls<br />p-value<br />Matched OR*<br />95% CI†<br />Any lett...
7<br />6<br />5<br />Number of Cases<br />4<br />3<br />2<br />1<br />15<br />16<br />17<br />18<br />19<br />20<br />21<b...
7<br />6<br />5<br />Number of Cases<br />4<br />3<br />2<br />1<br />15<br />16<br />17<br />18<br />19<br />20<br />21<b...
7<br />6<br />5<br />Number of Cases<br />4<br />3<br />2<br />1<br />15<br />16<br />17<br />18<br />19<br />20<br />21<b...
7<br />6<br />Number of Cases<br />OR<br />5<br />4<br />3<br />WI<br />2<br />WI<br />1<br />15<br />16<br />17<br />18<b...
Dole Classic Romaine Salad Recovered from Case-Households<br />Shared common "Best if Used By” Date and production code<br />
Product Traceback<br />Single processing plant (Soledad, CA)<br />Production Date of September 7, 2005<br />Lettuce harves...
PFGE Patterns of E. coli O157:H7 Isolates from Lettuce<br />Source<br />Initial Minnesota Case-patient<br />Classic Romain...
Why Epidemiologic Links May Not be Identified for Cases in a PFGE Cluster<br />Cases have imperfect recall<br />Common exp...
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Investigating Foodborne Illness Outbreaks With Attorney William Marler

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Investigating Foodborne Illness Outbreaks With Attorney William Marler

  1. 1. Defense Research Institute<br />Making the Causal Link: Investigating Foodborne Disease OutbreaksWilliam D. Marler, Esq.<br />
  2. 2. CDC Estimates of Foodborne Illness<br />48 million cases of foodborne illness annually<br />125,000 hospitalizations<br />3,000 deaths<br />
  3. 3. Estimates Differ From Actual Counts <br />Annual E. coli O157 estimates<br />62,000 illnesses<br />1,800 hospitalizations<br />52 deaths<br />But, only 2,621 E. coli 0157 cases were reported in 2005 <br />
  4. 4. Notifiable/Reportable Diseases<br />Reporting authorized by Congress in 1878<br />Nationally Reportable Diseases(food or water borne origin)Botulism, Cryptosporidiosis, Cyclosporiasis, Giardiasis, Hemolytic Uremic Syndrome (post-diarrheal), Hepatitis A, Listeriosis, Salmonellosis, Shiga toxin producing Escherichia coli (STEC), Shigellosis, Trichinosis, Vibriosis<br />http://www.cdc.gov/ncphi/disss/nndss/phs/infdis2008.htm<br />
  5. 5. Pathway of a Foodborne Illness Investigation<br />Health Care Provider <br />Ill person<br />Specimen collection<br />Organism identified <br />
  6. 6. Pathway of a Foodborne Illness Investigation<br />Health Care Provider <br />Ill person<br />Specimen collection<br />Public Health Laboratory<br />Organism identified <br />If there are more ill persons than expected, an OUTBREAK might be underway.<br />Epidemiologic investigation<br />
  7. 7. How Do We Know If There Is an Excess?<br />Public Health Surveillance<br />The ongoing collection, analysis, interpretation and dissemination of health data directed towards the control and prevention of diseases.<br />
  8. 8. Pathway of a Foodborne Illness Investigation<br />Health Care Provider <br />Ill person<br />Specimen collection<br />Public Health Laboratory<br />Organism identified <br />Product Recall<br />Epidemiologic investigation<br />Environmental investigation<br />Product Trace Back<br />
  9. 9. Typical Steps of an Outbreak Investigation<br />Establish that an outbreak is occurring<br />Verify the diagnosis<br />Define and identify cases<br />Orient the data in terms of person, place, and time<br />Develop and test the hypotheses<br />Refine the hypotheses and carry out additional studies<br />Implement control and prevention measures<br />Report findings<br />
  10. 10. A Word to the Wise!<br />No mandatory list of how to proceed<br />No set order of steps to take<br />Investigation is dynamic: case definition, line listings, descriptive epidemiology, hypotheses can change<br />Expect the unexpected<br />
  11. 11. Investigative Partners<br />Laboratory investigators<br />Microbiologic diagnosis<br />Virology/Parasitic Labs<br />Molecular analysis<br />Epidemiologic investigators<br />Individual case interviews<br />Outbreak investigation<br />Cohort studies<br />Case/control studies<br />Environmental investigators<br />Facility investigation<br />Environmental sampling<br />Product traceback<br />
  12. 12. Epidemiology–Basic Tools of the Trade<br />Real-time interviewing with a broad-based exposure questionnaire<br />Symptoms<br />Incubation<br />Duration<br />Food History<br />Medical Attention<br />Suspected source<br />Others Ill<br />
  13. 13. Pulsed Field Gel Electrophoresis (PFGE)<br />A Powerful Outbreak Detection Tool <br />Process separates chromosomal fragments of intact bacterial genomic DNA grown from patient isolate<br />Results in 10 to 20 DNA fragments which distinguish bacterial strains<br />Genetic relatedness among strains is based on similarities of the DNA patterns<br />Outbreak strains are those that are epidemiologically linked AND genetically linked<br />
  14. 14. Questions to Consider in Assessing PFGE Clusters<br />How common is thePFGE subtype?<br />How many cases are there?<br />Over what time frame did cases occur?<br />What is the geographic distribution of cases?<br />What are the case demographics? <br />Do any of the cases have a “red flag” exposure?<br />
  15. 15. E. coli O157:H7 Outbreak, Minnesota, September 2005<br />Thanks to MN DOH for use of the following slides!<br />Team Diarrhea<br />
  16. 16. Outbreak Detection<br />September 27, 2005<br /><ul><li>Three O157 isolates with indistinguishable PFGE patterns identified by Minnesota Public Health Laboratory
  17. 17. PFGE pattern new in Minnesota, rare in United States
  18. 18. 0.35% of patterns in National Database
  19. 19. Patients reported eating prepackaged salad; no other potential common exposures evident</li></li></ul><li>7<br />6<br />5<br />Number of Cases<br />4<br />3<br />2<br />1<br />15<br />16<br />17<br />18<br />19<br />20<br />21<br />22<br />23<br />24<br />25<br />26<br />27<br />28<br />29<br />30<br />1<br />2<br />3<br />4<br />14<br />September<br />October<br />Date of Onset 2005<br />E. coli O157:H7 Cases Associated with Dole Prepackaged Lettuce<br />Initial cluster of 3 isolates among MN residents identified.<br />
  20. 20. Outbreak Investigation - Methods<br />September 28–29, 2005<br />Additional O157 isolates received at the MDOH and subtyped by PFGE<br />7 isolates demonstrated outbreak PFGE subtype <br />Supplemental interview form created<br />Case-control study initiated<br />
  21. 21.
  22. 22. 7<br />6<br />5<br />Number of Cases<br />4<br />3<br />2<br />1<br />15<br />16<br />17<br />18<br />19<br />20<br />21<br />22<br />23<br />24<br />25<br />26<br />27<br />28<br />29<br />30<br />1<br />2<br />3<br />4<br />14<br />September<br />October<br />Date of Onset 2005<br />E. coli O157:H7 Cases Associated with Dole Prepackaged Lettuce<br />Case-control study initiated.<br />Initial cluster of 3 isolates among MN residents identified.<br />
  23. 23. Case-Control Study Results<br />Cases<br />Exposure<br />Controls<br />p-value<br />Matched OR*<br />95% CI†<br />Any lettuce<br />9/10<br />17/26<br />3.5<br />0.5–25.0<br />0.17<br />Prepackaged lettuce salad<br />9/10<br />10/26<br />8.4<br />1.2–59.6<br />0.01<br />Dole prepackaged lettuce salad<br />9/10<br />5/23<br />0.002<br />10.1<br />1.5–67.3<br />*OR = odds ratio† CI = confidence interval<br />
  24. 24. 7<br />6<br />5<br />Number of Cases<br />4<br />3<br />2<br />1<br />15<br />16<br />17<br />18<br />19<br />20<br />21<br />22<br />23<br />24<br />25<br />26<br />27<br />28<br />29<br />30<br />1<br />2<br />3<br />4<br />14<br />September<br />October<br />Date of Onset 2005<br />E. coli O157:H7 Cases Associated with Dole Prepackaged Lettuce<br />Case-control study implicated Dole salad.<br />Case-control study initiated.<br />Initial cluster of 3 isolates among MN residents identified.<br />
  25. 25. 7<br />6<br />5<br />Number of Cases<br />4<br />3<br />2<br />1<br />15<br />16<br />17<br />18<br />19<br />20<br />21<br />22<br />23<br />24<br />25<br />26<br />27<br />28<br />29<br />30<br />1<br />2<br />3<br />4<br />14<br />September<br />October<br />Date of Onset 2005<br />E. coli O157:H7 Cases Associated with Dole Prepackaged Lettuce<br />CDC, FDA notified.<br />Case-control study implicated Dole salad.<br />Case-control study initiated.<br />Initial cluster of 3 isolates among MN residents identified.<br />
  26. 26. 7<br />6<br />5<br />Number of Cases<br />4<br />3<br />2<br />1<br />15<br />16<br />17<br />18<br />19<br />20<br />21<br />22<br />23<br />24<br />25<br />26<br />27<br />28<br />29<br />30<br />1<br />2<br />3<br />4<br />14<br />September<br />October<br />Date of Onset 2005<br />E. coli O157:H7 Cases Associated with Dole Prepackaged Lettuce<br />CDC, FDA notified.<br />Case-control study implicated Dole salad.<br />Case-control study initiated.<br />Initial cluster of 3 isolates among MN residents identified.<br />
  27. 27. 7<br />6<br />Number of Cases<br />OR<br />5<br />4<br />3<br />WI<br />2<br />WI<br />1<br />15<br />16<br />17<br />18<br />19<br />20<br />21<br />22<br />23<br />24<br />25<br />26<br />27<br />28<br />29<br />30<br />1<br />2<br />3<br />4<br />14<br />September<br />October<br />Date of Onset 2005<br />E. coli O157:H7 Cases Associated with Dole Prepackaged Lettuce (N=26)<br />Minnesota<br />Additional states<br />
  28. 28. Dole Classic Romaine Salad Recovered from Case-Households<br />Shared common "Best if Used By” Date and production code<br />
  29. 29. Product Traceback<br />Single processing plant (Soledad, CA)<br />Production Date of September 7, 2005<br />Lettuce harvested from any 1 of 7 fields<br />
  30. 30. PFGE Patterns of E. coli O157:H7 Isolates from Lettuce<br />Source<br />Initial Minnesota Case-patient<br />Classic RomaineBag #1<br />Classic Romaine<br />Bag #2<br />
  31. 31. Why Epidemiologic Links May Not be Identified for Cases in a PFGE Cluster<br />Cases have imperfect recall<br />Common exposures can be difficult to link (e.g., eggs, chicken)<br />Secondary transmission<br />Cross-contamination exposure<br />There isn’t a common source<br />
  32. 32. CDC 2005 Cluster Investigations<br />E. coli O157 Salmonella<br />Patterns Submitted 5,376 29,168<br />Clusters Identified 67 176<br />Multi-state Clusters 36 152<br />Epi Investigation 19 30<br />Vehicle Implicated 4 8<br />Regulatory Activity 4 8<br />
  33. 33. Questions?<br />

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