Outbreak Investigations: The Minnesota Perspective A Dynamic Process Carlota Medus, PhD, MPH Epidemiologist Principal Foodborne Diseases Unit Minnesota Department of Health
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 2005 2006 2007 2008
Selected Notable Foodborne Outbreak Investigations at MDH
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 http://healthinspections.com/articles.cfm?yxj0awnszuleptexma==
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
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
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
Selected Notable Foodborne Outbreak Investigations at MDH
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
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
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
Minnesota Approach to Investigation of PFGE Clusters: Dynamic Cluster Investigation Model Case #1 Case #2 Case #3 Case #4
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
Dynamic Cluster Investigation-Pot Pies Initial trawling questionnaire interview date 9/10 9/27 10/3 night 10/4 afternoon 1 2 3 PP 4 Exposure added trawling questionaire Consumed Banquet PP 10/4 evening 10/4 morning Re-interviewed cases about frozen foods and pot pies
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
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
Standard Questionnaire for Salmonella, E. coli O157 cases
Team Diarrhea Liz Gaston EnHS-Expected graduation Sep. 2010 Team D since Jun. 2009 Anthony Guzzardo Epi-Expected graduation Sep. 2011 Team D since Aug. 2009 Amy Saupe Epi-Expected graduation Sep. 2011 Team D since Jun. 2009 Seth Swanlund Epi-Expected graduation Sep. 2011 Team D since Jun. 2009 Kelsey Wick Epi-Expected graduation Sep. 2011 Team D since Aug.2009 Amber Koskey EnHS-Expected graduation Sep. 2010 Team D since Oct. 2009 UPDATED Jan 2010
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
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
Case-Control Study Results Exposure Cases Controls Matched OR* 95% CI p-value Any lettuce 9/10 17/26 3.5 0.5 25.0 Prepackaged lettuce salad 9/10 10/26 8.4 1.2 59.6 0.17 0.01 Brand A prepackaged lettuce salad 9/10 5/23 10.1 1.5 67.3 0.002 * OR = odds ratio CI = confidence interval
E. coli O157:H7 Cases Associated with Brand A Prepackaged Lettuce by Date of lllness Onset Number of Cases 7 6 5 4 3 2 1 Case-control study implicated Brand A salad Case-control study initiated Initial cluster of 3 isolates among MN residents identified 14 15 16 17 18 19 20 21 22 23 24 25 September Date of Onset 2005 26 27 28 29 30 1 2 3 4 October
E. coli O157:H7 MN744 Cases by Date of Isolate Receipt in MDH Public Health Laboratory, September-October 2007 Number of Cases 7 6 5 4 3 2 1 3rd case household: Brand A Ground Beef Patties 2 case households: Brand A Ground Beef Patties 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6 September October Date of Isolate Receipt at MDH Lab
E. coli O157:H7 MN744 Cases by Date of Isolate Receipt in MDH Public Health Laboratory, September-October 2007 Number of Cases 7 6 5 4 3 2 1 Product Packaging Information from 2 case households 3rd case household Brand A Ground Beef Patties 2 case households: Brand A Ground Beef Patties 16 17 18 19 20 21 22 23 24 25 26 27 September 28 29 30 1 2 3 4 5 6 October Date of Isolate Receipt at MDH Lab
Same date 1 minute apart Same line
E. coli O157:H7 MN744 Cases by Date of Isolate Receipt in MDH Public Health Laboratory, September-October 2007 Number of Cases 7 6 5 4 3 2 1 Product Packaging Information from 2 case households 3rd case household Brand A Ground Beef Patties 2 case households: Brand A Ground Beef Patties 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6 September October Date of Isolate Receipt at MDH Lab
Number of E. coli O157:H7 MN744 Cases by State (n=45)* 10 7 6 CT (1) 2 MD (3) 2 1 1 3 2 1 3 3 * Preliminary data as of 11/2/07
Multi-State Salmonella Typhimurium Outbreak Associated with Cold Stone Creamery Ice Cream, 2005 Photo credit: B. Keene, 2005
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
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 6 5 4 3 2 MN OR OR MI MN MN IL 1 OR OH OH MN WA WA OR WA WA OR VA VA VA WA MA CA 21 22 23 24 25 26 27 28 29 30 31 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 ~ 29 30 01 02 03 04 May June July MN Chain A voluntarily pulled cake batter ice cream from stores Outbreak detected 2005 Date of Onset
Salmonella Typhimurium Peanut Butter Outbreak, 2008-2009
December 3, 2008
1 st 11 cases in MN Institutional link, Implication of PB
Salmonella Typhimurium Cases in Minnesota Associated with the PCA Peanut Butter Outbreak, by Week of Isolate Receipt in MDH Lab, November December 2008 12 11 10 9 Number of Cases 8 7 6 5 4 3 2 1 2 9 16 23 30 7 14 21 28 4 11 18 25 1 8 15 22 November December January February 2008 2009 Week of Isolate Receipt (Week Ending)
S. Typhimurium Investigation, 2008-2009 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
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
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
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
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
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
January 9, 2009
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
1 st 11 cases in MN Institutional link, Implication of PB
Case-Control Study Results Exposure Cases Controls Matched OR* 95% CI p-value Prepackaged PB crackers 73% 17% 12.3 5.5 30.9 Austin PB crackers 43% 3% 29.7 9.0-154.7 <0.001 <0.001 Keebler PB crackers 20% 4% 5.4 1.7 18.3 0.003 * OR = odds ratio CI = confidence interval
1 st 11 cases in MN Institutional link, Implication of PB
CDC.gov
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
Salmonella Typhimurium Cases in Minnesota Associated with the PCA Peanut Butter Outbreak, by Week of Isolate Receipt in MDH Lab, November 2008 - February 2009 12 11 10 9 Number of Cases 8 7 6 5 4 3 2 1 2 9 16 23 30 7 14 21 28 4 11 18 25 1 8 15 22 November December January February 2008 2009 Week of Isolate Receipt (Week Ending)
Information current as of 12 PM June 12, 2009 3916 entries in list
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
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
Salmonella Saintpaul Outbreak, 2008
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
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
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 Email addresses: firstname.lastname@state.mn.us Main phone: 651 201 5414 Foodborne fax: 651 201 5082
Contact Information Carlota Medus, PhD, MPH Epidemiologist Principal carlota.medus@state.mn.us 651.201.5527 651.201.5414