Outbreak Investigations: The Minnesota Perspective A Dynamic Process

Transcription

1 Outbreak Investigations: The Minnesota Perspective A Dynamic Process Carlota Medus, PhD, MPH Epidemiologist Principal Foodborne Diseases Unit Minnesota Department of Health

2 Some Recent Notable Multi-state Foodborne Outbreaks of Salmonellosis Cake Mix 25 cases 9 states Peter Pan peanut butter 714 cases 48 states PCA peanut butter 691 cases 46 states Hot peppers 1,442 cases 44 states Tomatoes 183 cases 21 states Veggie Booty 70 cases 23 states Pot pies 401 cases 42 states

3 Selected Notable Foodborne Outbreak Investigations at MDH

4 The most dangerous states for eating out are Florida, California, Minnesota, Ohio, and New York 1. Florida 74 outbreaks 2. California 69 outbreaks 3. Minnesota 55 outbreaks

5 Epidemiological Outbreak Investigation Essential elements Case interviews Information from different sources Sense of urgency/rapid response Flexibility- may need to reexamine evidence Tools Statistics Laboratory data, e.g., PFGE, MLVA Food testing Product tracing

6 Epidemiological Outbreak Investigation Essential elements Issues Case interviews: not done, not done promptly Information from different sources: overreliance on case-control studies Sense of urgency/rapid response: Waiting until there are at least X number of cases Flexibility- unwillingness to reexamine evidence

7 Epidemiological Outbreak Investigation Tools Issues Statistics- believing that without a significant p value we have not implicated a vehicle Laboratory data, e.g., PFGE, MLVA- overreliance on subtyping while neglecting the basic epi Food testing- believing that without a positive food sample we have not implicated a vehicle Product tracing- traditionally not started until the vehicle has been implicated

8 Selected Notable Foodborne Outbreak Investigations at MDH

9 FoodNet Active Surveillance Network Oregon California Colorado New Mexico Minnesota New York Connecticut Maryland Tennessee Georgia - Centers for Disease Control and Prevention - U.S. Department of Agriculture - Food and Drug Administration

10 FoodNet Active Surveillance Network Determine the burden of foodborne illness in the United States Monitor trends in the burden of specific foodborne illness over time Attribute the burden of foodborne illness to specific foods and settings Disseminate information that can lead to improvements in public health practice and the development of interventions to reduce the burden of foodborne illness

11 Minnesota Surveillance System Centralized at the state level Isolate submission to the Minnesota Department of Health (MDH) Real-time pulsed-field gel electrophoresis (PFGE) Salmonella, E. coli O157:H7 Real-time interviews of all cases Iterative, dynamic process

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

13 Interviewing Cases: Minnesota Basic Philosophy Interview all cases in surveillance Interview ASAP Collect details on specific exposures Dates Restaurant, grocery store names Brand names Open-ended food histories

14 Dynamic Cluster Investigation-Pot Pies Initial trawling questionnaire interview date 9/10 9/27 10/3 night 10/4 afternoon PP 4 Exposure added trawling questionaire Consumed Banquet PP 10/4 evening 10/4 morning Re-interviewed cases about frozen foods and pot pies

15 Interviewing Cases: Minnesota Basic Philosophy Interviewing all cases not the norm in the U.S. even during cluster investigations 2008 Salmonella Saintpaul outbreak associated with jalapeño peppers: 1,495 cases, 419 (28%) interviewed 2009 Salmonella Montevideo outbreak associated with Italian meats (ongoing) 238 cases, 108 (45%) interviewed

16 Interviewing Cases: Minnesota Basic Philosophy Interview all cases Interview ASAP Collect details on specific exposures Dates Restaurant, grocery store names Brand names Open-ended food histories

17 Standard Questionnaire for Salmonella, E. coli O157 cases

18

19

20

21

22

23

24

25

26

27

28

29

30 Team Diarrhea Liz Gaston EnHS-Expected graduation Sep Team D since Jun Anthony Guzzardo Epi-Expected graduation Sep Team D since Aug Amy Saupe Epi-Expected graduation Sep Team D since Jun Seth Swanlund Epi-Expected graduation Sep Team D since Jun Kelsey Wick Epi-Expected graduation Sep Team D since Aug.2009 Amber Koskey EnHS-Expected graduation Sep Team D since Oct UPDATED Jan 2010

31 Prepackaged Salad O157 Outbreak, 2005 September 27, 2005 Three O157 isolates with indistinguishable PFGE patterns identified by Minnesota Public Health Laboratory PFGE pattern new in Minnesota, rare in United States 0.35% of patterns in National Database

32

33 Outbreak Investigation - Methods September 28 29, 2005 Additional O157 isolates received and subtyped by PFGE 7 isolates demonstrated outbreak PFGE subtype Supplemental interview form created Case-control study initiated Age-matched community controls recruited through sequential digit dialing anchored on case s telephone number

34 Case-Control Study Results Exposure Cases Controls Matched OR* 95% CI p-value Any lettuce 9/10 17/ Prepackaged lettuce salad 9/10 10/ Brand A prepackaged lettuce salad 9/10 5/ * OR = odds ratio CI = confidence interval

35 E. coli O157:H7 Cases Associated with Brand A Prepackaged Lettuce by Date of lllness Onset Number of Cases Case-control study implicated Brand A salad Case-control study initiated Initial cluster of 3 isolates among MN residents identified September Date of Onset October

36 E. coli O157:H7 MN744 Cases by Date of Isolate Receipt in MDH Public Health Laboratory, September-October 2007 Number of Cases rd case household: Brand A Ground Beef Patties 2 case households: Brand A Ground Beef Patties September October Date of Isolate Receipt at MDH Lab

37

38 E. coli O157:H7 MN744 Cases by Date of Isolate Receipt in MDH Public Health Laboratory, September-October 2007 Number of Cases Product Packaging Information from 2 case households 3rd case household Brand A Ground Beef Patties 2 case households: Brand A Ground Beef Patties September October Date of Isolate Receipt at MDH Lab

39 Same date 1 minute apart Same line

40 E. coli O157:H7 MN744 Cases by Date of Isolate Receipt in MDH Public Health Laboratory, September-October 2007 Number of Cases Product Packaging Information from 2 case households 3rd case household Brand A Ground Beef Patties 2 case households: Brand A Ground Beef Patties September October Date of Isolate Receipt at MDH Lab

41 Number of E. coli O157:H7 MN744 Cases by State (n=45)* CT (1) 2 MD (3) * Preliminary data as of 11/2/07

42 Multi-State Salmonella Typhimurium Outbreak Associated with Cold Stone Creamery Ice Cream, 2005 Photo credit: B. Keene, 2005

43 Salmonella Typhimurium Associated with Cold Stone Creamery Ice Cream, 2005 June 29, 2005 Cluster of 4 S. Typhimurium isolates with matching PFGE patterns identified by MDH subtype new to PulseNet national database 4 persons interviewed and reported eating cake batter ice cream from 2 separate Cold Stone Creamery outlets 5 cases in WA and 2 cases in OH with matching PFGE subtypes; 3 WA cases interviewed and 2 reported eating cake batter ice cream

44

45 Cold Stone Creamery S. Typhimurium Outbreak Illness Onset Dates of Cases by State of Residence (n=24) CA California MA Massachusetts MN Minnesota OR Oregon IL Illinois MI Michigan OH Ohio VA Virginia WA Washington Number of Cases MN OR OR MI MN MN IL 1 OR OH OH MN WA WA OR WA WA OR VA VA VA WA MA CA ~ May June July MN Chain A voluntarily pulled cake batter ice cream from stores Outbreak detected 2005 Date of Onset

46

47

48 Salmonella Typhimurium Peanut Butter Outbreak,

49 December 3, 2008

50 1 st 11 cases in MN Institutional link, Implication of PB

51 Salmonella Typhimurium Cases in Minnesota Associated with the PCA Peanut Butter Outbreak, by Week of Isolate Receipt in MDH Lab, November December Number of Cases November December January February Week of Isolate Receipt (Week Ending)

52 S. Typhimurium Investigation, November 17-24, 2008 MDH received 3 outbreak isolates Early December Leading hypothesis in national investigation was chicken Restaurant-associated outbreak in another state with three PFGE patterns Ultimately shown to be a red herring

53 Minnesota S. Typhimurium Investigation December 10-19, 2008 MDH received 8 additional outbreak isolates All chicken for first 4 cases traced back - source did not converge with other state s investigation or with each other First 8 interviewed cases reported eating peanut butter Suspicious, but not enough evidence to implicate one product, or even peanut butter overall, as the vehicle

54 Minnesota S. Typhimurium Investigation December 22, 2008 Medical director of LTCF (LTCF A) in northern MN reports confirmed Salmonella infections in 3 residents Specimens from 2 other residents pending All five cases confirmed with outbreak strain of S. Typhimurium Outbreak cases identified in other institutions: LTCF B, elementary school

55 Minnesota S. Typhimurium Investigation LTCF A, LTCF B, elementary school all purchased food from a common distributor in Fargo, North Dakota Obtained and reviewed invoices Only food common to the 3 institutions was King Nut Creamy Peanut Butter Open tub of King Nut peanut butter collected from LTCF A by Minnesota Department of Agriculture on January 5

56 Minnesota S. Typhimurium Investigation January 9, 2009 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 ate at a county courthouse Invoices from OR facility with 1 case also revealed King Nut peanut buttercafeteria

57 Minnesota S. Typhimurium Investigation January 9, 2009 No cases associated with institutions in distribution area for Company A facility in Twin Cities This facility did not distribute King Nut peanut butter However, we could not yet explain the specific vehicle for cases not related to institutions

58 January 9, 2009

59

60

61 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 peanut paste from PCA market withdrawal by Kellogg Crackers implicated in national case-control study Outbreak strain ultimately isolated

62 1 st 11 cases in MN Institutional link, Implication of PB

63 Case-Control Study Results Exposure Cases Controls Matched OR* 95% CI p-value Prepackaged PB crackers 73% 17% Austin PB crackers 43% 3% <0.001 <0.001 Keebler PB crackers 20% 4% * OR = odds ratio CI = confidence interval

64 1 st 11 cases in MN Institutional link, Implication of PB

65 CDC.gov

66 Minnesota Outbreak Cases (n=44) Age range, 4 mos. 98 yrs 16 (36%) hospitalized 3 deaths 24 (55%) with exposure to King Nut PB 14 LTCF residents, 9 at work or school, 1 at a retail ice cream store 11 (25%) likely associated with Austin/Keebler PB crackers 9 (20%) undetermined exposure

67 Salmonella Typhimurium Cases in Minnesota Associated with the PCA Peanut Butter Outbreak, by Week of Isolate Receipt in MDH Lab, November February Number of Cases November December January February Week of Isolate Receipt (Week Ending)

68

69 Information current as of 12 PM June 12, entries in list

70

71 Challenges Contaminated ingredient that went into many products- impossible to figure out just by interviewing cases Cases that ate King Nut were not always interviewable No significant p value at the time of MDH s press release

72

73 Key Minnesota Practices Close working relationship between MN Departments of Health and Agriculture Tracebacks inform the investigation Willing to trace back foods that are not yet implicated Willing to test suspect foods Relationship with health care providers Centralized investigations

74 Salmonella Saintpaul Outbreak, 2008

75

76 Epidemiological Outbreak Investigation Essential elements Case interviews Information from different sources Sense of urgency/rapid response Flexibility- may need to reexamine evidence Tools Statistics Laboratory data, e.g., PFGE, MLVA Food testing Product tracing

77 Power of Epidemiological Data Schwan s ice cream, 1994 Results of epi study and press release October 7 Salmonella isolation from ice cream October 17 Had our announcement been delayed until the receipt of this confirmation, many more people would have become ill after eating this product. * *Hennessy NEJM 1996

78 Kirk Smith, DVM, MS, PhD Supervisor Foodborne, Vectorborne, and Zoonotic Diseases Unit Dawn Kaehler Health Program Representative Theresa Weber Health Program Representative Carlota Medus, PhD, MPH Epidemiologist Stephanie Meyer, MPH Epidemiologist Erin Hedican, MPH Epidemiologist Trisha Robinson, MPH Epidemiologist Josh Rounds, MPH Epidemiologist addresses: Main phone: Foodborne fax:

79 Contact Information Carlota Medus, PhD, MPH Epidemiologist Principal