The PCA Peanut Butter Outbreak - Minnesota s Involvement and Perspective

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1 The PCA Peanut Butter Outbreak - Minnesota s Involvement and Perspective Dave Boxrud, MS Laboratory Supervisor Minnesota Department of Health Stephanie Meyer, MPH Epidemiologist Minnesota Department of Health

2 Foodborne Disease Surveillance and Outbreak Detection MN Department of Health lab practices MN Department of Health epi methods Collaboration with MN Dept of Agriculture PCA Peanut Butter Outbreak PFGE/Cluster identification Epidemiologic investigation Minnesota s role and perspective

3 Activities Done In Real Time : Isolate acquisition Subtype analysis/reporting } Lab Case interviewing Cluster investigation } Epi

4 Campylobacter E. coli O157 and non- O157 STEC Salmonella Shigella Listeria monocytogenes

5 Subtyping in MN Concurrent Isolate received Biochemicals + TSBA 1 day 2 days Enterics Serotyping Hours - days PFGE 1 day

6 Pattern Comparison Local database PN Clusters/OB National database

7 Daily Report from MDH Lab to Epi Cultures Confirmed Yesterday

8 Daily Report from MDH Lab to Epi Cultures Confirmed or Subtyped in the Past 30 Days

9 Daily Report from MDH Lab to Epi Historical perspective

10 Daily Report from MDH Lab to Epi PulseNet clusters

11 Cluster Communication

12 Minnesota Surveillance Philosophy-Epidemiology Interview all cases, ASAP Average interview time, 27 minutes Collect details on specific exposures Restaurant, grocery store names Brand names Open-ended food histories

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14 Minnesota Surveillance Philosophy Investigation of all PFGE clusters Intensity/resource expenditure depends on the exact nature of the cluster Follow leads aggressively

15 Response for PFGE Clusters Minimum: Compare case interviews Maximum: Case-control study Food Testing: Before, during, or after casecontrol study Epidemiologic product tracing

16 Outbreak Vehicle Implication Need More than Just a Statistical Association A true exposure should account for high proportion of cases Biologic plausibility right incubation, plausible vehicle, etc. Distribution of cases vs. distribution of food Converging tracebacks Explanation of outliers

17 Food Tracebacks Traditionally done after a food vehicle is implicated by other means (epi, lab testing) Can be valuable as part of epidemiologic investigation to implicate a food item Epidemiologic traceback Especially for generic foods Can do quickly, if not for regulatory purposes Potential for confusion if interpreted by industry as implication of product

18 MDH-MDA Collaboration

19 One Approach to Investigation of PFGE Clusters PFGE Cluster Identified Hypothesis Generating Questionnaire Used Hypothesis Determined Case-Control Study Started

20 Minnesota Approach to Investigation of PFGE Clusters: Dynamic Cluster Investigation Model Case #1 Case #2 Case #3 Case #4

21 PCA Peanut Butter Salmonella Typhimurium outbreak Winter

22 National Outbreak Detection November 5 SDC reported a cluster of 2 Salmonella (serotype pending) November 6 CDC responded that the pattern had been seen 13 times from 12 localities in the last 60 days November 25 CDC initiated epidemiologic assessment of cluster, then at 35 isolates

23 National Outbreak Detection December 2 CDC initiated assessment of a second S. Typhimurium cluster, with 45 isolates PFGE patterns of the 2 clusters closely related Isolates were geographically and temporally clustered Cluster investigations merged

24 December 3, 2008

25 Minnesota S. Typhimurium Investigation November MDH received 3 outbreak isolates Early December Leading hypothesis in national investigation was chicken Restaurant associated outbreak in another state with a third PFGE subtype Ultimately shown to be a red herring

26 National Investigation December 10-19, 2008 MDH received 8 additional outbreak isolates All chicken for first 4 cases traced back - sources did not converge First 8 interviewed cases had reported eating peanut butter Suspicious, but not enough evidence to implicate one product, or even peanut butter overall, as the vehicle

27 Minnesota S. Typhimurium Investigation December 22 Medical director of LTCF (LTCF A) in northern MN reported confirmed Salmonella infections in 3 residents, 2 more pending All five cases confirmed with outbreak strain of S. Typhimurium Cases lived in 2 of 3 separate houses Meals prepared in central kitchen No ill staff

28 Minnesota S. Typhimurium Investigation December 22 Single S. Typhimurium outbreak case reported in resident of second LTCF (LTCF B) in same city as LTCF A December Two outbreak cases interviewed, attended same elementary school Menus and food invoices from LTCFs A, B, and elementary school obtained

29 Minnesota S. Typhimurium Investigation LTCFs A, B, and elementary school all purchased food from the same distributor in Fargo, North Dakota Only food common to the 3 institutions was King Nut Creamy Peanut Butter Open container of King Nut peanut butter collected from LTCF A by Minnesota Department of Agriculture Rapid Response Team (MDA RRT) on January 5

30 Minnesota S. Typhimurium Investigation January 6 S. Typhimurium outbreak case reported in resident of third LTCF (LTCF C) Case died In weeks prior to onset, case had consumed only a few solid food items, including peanut butter and toast LTCF C also served King Nut Creamy Peanut Butter

31 Minnesota S. Typhimurium Investigation January 9 Case count at 30 Five additional cases related to institutions that received King Nut peanut butter from ND distributor A 2 worked at LTCFs 2 attended separate universities 1 worked at a county courthouse cafeteria MN Dept of Ag confirmed Salmonella in open container of King Nut peanut butter

32 Peanut Butter Exposure Number of cases Case with unknown exposure Case with known exposure to King Nut PB November December Date Received in MDH laboratory

33 Minnesota S. Typhimurium Investigation North Dakota distributor also had a distribution center in Twin Cities No cases were associated with institutions in the distribution area for the Twin Cities center This distribution center did not carry King Nut peanut butter

34 The Decision Epidemiologic evidence supported King Nut peanut butter as a vehicle for a portion of cases in Minnesota Positive finding in an open container of peanut butter No serotype, no PFGE Friday (approximately 4pm) Other agencies/federal input on the national investigation

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38 Week of January 12, 2009 State health depts. report cases had eaten Austin, Keebler PB crackers Plant in NC that makes these crackers found to use PCA peanut paste Outbreak strain isolated from Austin PB crackers Canada (crackers purchased in Maine) Oregon

39 Peanut Butter Testing Method: Adaptation of BAM procedure Screening done on both the Vidas and BAX g samples tested since 1/1/ g cracker samples tested, all negative 7 Confirmed positive samples 6 S. Typhimurium 1 S. Tennessee

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41 Minnesota Outbreak Cases (n=45) Age range, 4 mos. 98 yrs 16 (36%) hospitalized 3 deaths 24 (53%) with exposure to King Nut PB 14 LTCF residents, 9 at work or school, 1 at a retail ice cream store 12 (27%) likely associated with Austin/Keebler PB crackers 9 (20%) undetermined exposure

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43 Conclusions Potential for multi-pattern outbreaks Exposure information key to solving outbreak Contaminated ingredients used in multiple foods difficult to detect Local/regional tracebacks can be key in an outbreak investigation MDH Lab/MDH Epi/MDA RRT/MDA lab interaction

44 Acknowledgements MDH Enterics Laboratory MDH PFGE Laboratory MDH Epidemiology staff MDA Rapid Response Team MDA Laboratory CDC OutbreakNet FDA USDA State and Local agencies that contributed to this investigation

45 Questions?

46 MDA Salmonella Algorithm

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48 FDA Investigation