Alida Sorenson - Cool logic; solving a norovirus outbreak in a commercially-distributed food
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Cool logic; solving a norovirus outbreak in a commercially-distributed food - Alida Sorenson, from the 2018 Allen D. Leman Swine Conference, September 15-18, 2018, St. Paul, Minnesota, USA. More presentations at http://www.swinecast.com/2018-leman-swine-conference-material
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Alida Sorenson - Cool logic; solving a norovirus outbreak in a commercially-distributed food
- 1. Cool logic; solving a norovirus outbreak in a commercially- distributed food 2018 Allen D. Leman Swine Conference September 18, 2018 Alida Sorenson, MPH – Minnesota Department of Agriculture
- 2. Introduction • Graduate of the University of Minnesota − 2009 – Nutrition & Dietetics − 2014 – Masters of Public Health – Environmental Health • Former member of “Team Diarrhea” with the Minnesota Department of Health • Coordinator of the Minnesota Department of Agriculture Rapid Response Team (RRT)
- 3. What is a Rapid Response Team (RRT)? • FDA-funded program initiated in 2008 • National response network • MN RRT is involved in: − Foodborne illness outbreak − Contamination events − Natural disasters − Many moving parts / programs involved − Assistance in event management − Program needs that stretch beyond “routine”
- 4. What does ice cream have to do with swine? Photo source: http://minipiekitchen.com/maple-bacon- ice-cream/ OK…maybe not much BUT…
- 5. The Chain of Regulatory Responsibility
- 6. Background – Norovirus Outbreaks • Norovirus is the most common cause of acute gastrointestinal illness in the United States • In Minnesota, norovirus is the etiology for ~60% of foodborne outbreaks • Foodborne norovirus outbreaks usually caused by contamination at time of preparation Norovirus 57% Bacterial Intoxications 10% Salmonella 14% STEC 6% Other/unknown 13% Confirmed Foodborne Outbreaks by Etiology, Minnesota,1999-2016
- 7. Background – Complaint System Almost all norovirus outbreaks identified through the Minnesota Department of Health (MDH) foodborne and waterborne illness hotline − Centralized complaint system − Illness reports collected and assessed at state level − Investigations initiated with state or local environmental health jurisdictions
- 8. Outbreak Detection – Restaurant A August 8, 2016 • Received complaint − Gastrointestinal illness among 2 of 3 meal companions − Only common exposure: August 4 meal at Restaurant A − Incubation periods 29.5 and 32 hours Restaurant A
- 9. Outbreak Investigation – Restaurant A • Investigation initiated at Restaurant A − Lead agencies Hennepin County Human Services and Public Health Department, Epidemiology Minneapolis Health Department, Environmental Health − Norovirus interventions Restaurant clean/sanitize, education (hand hygiene, exclusions) Food worker interviews − Patron interviews (case finding, case-control study)
- 10. Investigation Results – Restaurant A • Two cases identified − Vegetarian tacos; Brand X raspberry chocolate chip ice cream • Five controls interviewed − Variety of other menu items; no ice cream • Five of 85 employees with vomiting/diarrhea − Illness onsets July 27 – August 6 Patron meal date: August 4 • Typical norovirus food handler outbreak?One employee: eats Brand X raspberry chocolate chip ice cream during most shifts
- 11. Outbreak Detection – Retail Locations August 15, 2016 • MDH foodborne illness hotline received another complaint − Gastrointestinal illness among 3 of 20 meal companions − Only common exposure: August 11 visit to Brand X Ice Cream’s Franklin retail location − All cases ate raspberry chocolate chip ice cream Healthy individuals ate a variety of other flavors
- 12. 12 FRANKLIN RETAIL UPTON RETAIL RESTAURANT A City of Minneapolis
- 13. 13 FRANKLIN RETAIL COMMISSARY UPTON RETAIL RESTAURANT A City of Minneapolis
- 14. Outbreak Detection – Private Party August 17, 2016 • Hennepin County Epidemiology received a complaint from a local country club − Gastrointestinal illness among attendees of a catered birthday event on August 13 Country club did not serve Brand X ice cream Symptoms/duration = norovirus; incubation periods too short − The group also ate together August 12 at a private home For dessert: Brand X ice cream
- 15. 15 FRANKLIN RETAIL COMMISSARY UPTON RETAIL RESTAURANT A PRIVATE PARTY City of Minneapolis
- 16. Brand X Ice Cream Flavor Cases n/n (%) Controls n/n (%) Odds Ratio p-value Vanilla 1/5 (20%) 1/10 (10%) 2.25 1.00 Chocolate 3/5 (60%) 1/10 (10%) 13.5 0.08 Raspberry Chocolate Chip 5/5 (100%) 2/9 (22%) -- 0.02 Private Party Case-Control Study Results
- 17. Norovirus Gastroenteritis Cases Associated with Brand X Ice Cream, by Meal Date Meal Date August 2016 NumberofCases Retail – Upton Restaurant A Private Party Laboratory-confirmed Retail – Franklin 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 1 2 3 4 5 6 7
- 18. Ice Cream X Commissary Kitchen August 16, 2016 • Raspberry chocolate chip ice cream ingredients: − Vanilla base mix, chocolate chips, frozen raspberries, sugar, stabilizer − No kill step for raspberries • Preparation involved no direct food worker handling • All 16 employees interviewed by Team Diarrhea students (MDH) − No illnesses reported
- 19. 31 Norovirus Gastroenteritis Cases Associated with Ice Cream, by Meal Date Meal Date 2016 NumberofCases Raspberry shipment of interest received at commissary 1 2 3 4 5 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 6 7 July August http://www.amcharts.com/visited_countries/
- 20. 31 Norovirus Gastroenteritis Cases Associated with Ice Cream, by Meal Date Meal Date 2016 NumberofCases Raspberry shipment of interest received at commissary 1 2 3 4 5 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 6 7 July August Product withdrawal initiated
- 21. Brand X Ice Cream Product Withdrawal Retail (2.5 gallon tubs) • Distributed to Brand X’s two retail locations and other venues (restaurants) − By August 19, 146 tubs returned to commissary
- 22. Sample Collection for Testing at FDA Center for Food Safety and Applied Nutrition (CFSAN) Laboratory Serbia (n=2) Chile (n=2) China (n=2) Six bags of frozen raspberries Ten 2.5 gallon containers
- 23. Product Testing Results FDA CFSAN & Office of Regulatory Science Laboratories Product Amount Tested Norovirus Results Vanilla Ice Cream 2 pints negative Chocolate Ice Cream 2 pints negative Raspberry Chocolate Chip Ice Cream 10 x 2.5 gallons positive Frozen Raspberries Chile: 2 bags Serbia: 2 bags China: 5 bags negative negative positive
- 24. Conclusions • Outbreak of norovirus associated with ice cream produced using contaminated frozen raspberries, sourced from China • Ice cream manufacturer has initiated a kill step for frozen raspberries
- 25. Discussion • Frozen berries: vehicle for hepatitis A virus, norovirus (Europe) • This is the first norovirus outbreak due to imported frozen berries in United States • Outbreak was tough to find − Outbreak-detection systems venue-focused, not sensitive to commercially distributed vehicles • Norovirus outbreaks due to commercially distributed foods likely more common • Are frozen berries a high-risk food?
- 26. Norovirus Frozen Berry Outbreaks 26 • “Largest outbreak in German history caused by imported strawberries” • New German recommendations for institutions catering for vulnerable populations -> heat frozen berries • January 2013, EU regulation: 5% of frozen strawberries imported from China to EU must be tested for norovirus
- 27. Norovirus Frozen Berry Outbreaks 27 http://ucfoodsafety.ucdavis.edu/files/223896.pdf
- 28. Investigation Partners & Acknowledgements MN Department of Agriculture Inspections (Lisa Ramacher) ● Laboratory (Matt Forstner) Hennepin County Human Services and Public Health Department Epidemiology (Carol Hooker, Erica Bagstad) ● Environmental Health Virginia Department of Health Laboratory ● Epidemiology CDC Jan Vinjé, Leslie Barclay, Aron Hall MN Department of Health Epidemiology (Amy Saupe, Joshua Rounds, Nicole Hedeen, Dana Eikmeier, Kirk Smith, Carlota Medus) ● Team Diarrhea ● Public Health Laboratory (Liz Horn, Ginette Dobbins, Elizabeth Cebelinski) City of Minneapolis Health Department Environmental Health FDA Office of Human and Animal Food Operations, Division 1 West ● Office of Regulatory Science ● CFSAN Brand X Ice Cream Photo Credit Brand X website http://bit.ly/1tMslG7
- 29. Thank You! | Questions? alida.sorenson@state.mn.us amy.saupe@state.mn.us
Editor's Notes
- You may be wondering where this presentation fits in to the conference. I thought that at first too, but this outbreak overview is an excellent example of how small our food world is getting. Not only can food travel around the world more quickly and easily, but it can also be saved or stored for longer than ever before. This means that a contaminated food item has a greater potential to cause illness. Whether we are talking about a pathogen like a virus in ice cream or in pork products, we all face the same challenge: how do we keep our food, our animals, and our people safe?
- Different links within Minnesota’s food chain are regulated by different agencies. For the purposes of this presentation, I will be focusing on work done by the Dept. of Ag. and the Dept. of Health, particularly, how a product like ice cream manufactured in Minnesota would be regulated. MDA inspects manufacturing facilities, like an ice cream production facility (or commissary), and would be notified if there are any issues during transport. MDA also inspects retail facilities where food is not consumed onsite (buy and leave), like grocery stores. MDH focuses on locations where food is consumed onsite, like an ice cream shop or restaurant.
- Norovirus is the most common cause of acute gastrointestinal illness in the United States. In Minnesota, norovirus is the etiology for about 60% of confirmed foodborne disease outbreaks. Due to transmission through the fecal-oral route, foodborne norovirus outbreaks are usually caused by contamination of food items at the time of preparation by food handlers who are shedding virus.
- Almost all norovirus outbreaks in Minnesota are identified through the Minnesota Department of Health (MDH) foodborne and waterborne illness hotline, which is a centralized complaint system where all illness reports are collected and assessed at the state level, and investigations are initiated with state or local environmental health jurisdictions when appropriate.
- On August 8, 2016, the hotline received a complaint of gastrointestinal illness among 2 of 3 meal companions. The ill individuals were from different households and claimed that their only common exposure was an August 4th meal at Restaurant A. Incubation periods were 29.5 and 32 hours. *PAUSE* You’ll notice I won’t say any names of the actual ice cream or restaurants during this presentation. We don’t share this information unless the investigation was made public or the facility had to conduct a recall.
- An investigation was immediately initiated at Restaurant A. Several local agencies with jurisdiction for this restaurant were notified. Lead agencies included Hennepin County Human Services and Public Health Department for local epidemiology, and the City of Minneapolis Health Department for environmental health. Sanitarians visited Restaurant A that day to put norovirus interventions into place, which included asking the restaurant to clean and sanitize with a product effective against norovirus, and provide education on hand hygiene and employee exclusions. Sanitarians interviewed food workers regarding illness history and job duties, and gathered patron contact information so that patron interviews could be conducted for case finding and a case-control study.
- Seven Restaurant A patrons were reached for interview and two cases were identified. Both cases ate vegetarians tacos and had Brand X raspberry chocolate chip ice cream. Five controls were interviewed - they had eaten a variety of other menu items, and had not eaten ice cream. All Restaurant A employees were interviewed, and five of 85 reported vomiting or diarrhea since July 21. Illness onsets for the employees ranged from July 27 through August 6. Recall that the patron meal date was August 4th. At this point, the investigation looked similar to a typical norovirus food handler-associated outbreak. However, *CLICK* later in the investigation we called employees back to ask about ice cream consumption, and learned that Brand X ice cream is a very popular treat among employees. One ill employee reported that she eats raspberry chocolate chip flavor during most of her shifts.
- About a week later, on August 15, the MDH foodborne illness hotline received another complaint. Gastrointestinal illness was reported among three of 20 meal companions whose only common exposure had been an August 11 visit to Brand X Ice Cream’s Franklin Ave retail location. All of the ill individuals had eaten raspberry chocolate chip ice cream; the well individuals had eaten a variety of other flavors.
- Here’s the Franklin retail location, also located in Minneapolis. Subsequently, additional illness complaints were received regarding this Franklin retail location, as well as Brand X Ice Cream’s other retail location on Upton Ave. *CLICK* *PAUSE*
- All ice cream sold at the retail locations and distributed to other facilities (including Restaurant A) is produced in Minneapolis at Brand X Ice Cream’s commissary kitchen. The kitchen is licensed and inspected by the Minnesota Department of Agriculture (MDA).
- On August 17, Hennepin County epidemiology received a complaint from a local country club. They had gotten a report of gastrointestinal illness among attendees of a catered birthday event held at the country club on August 13. Hennepin County forwarded the complaint to the MDH hotline and an investigation was initiated. Hennepin County sanitarians visited the country club, which reported that they sometimes serve ice cream, but do not have Brand X. The symptoms and durations for party attendees were characteristic of norovirus; however, incubation periods reported by cases during interviews were too short for a norovirus exposure at the country club. Though the group had denied other common exposures during the initial complaint report, *CLICK* it came to light during interviews that the party group, including everyone who was ill, had also eaten together the night prior on August 12 at a private home in Minnetonka. A full menu for this private event was not initially available, but one interviewee *CLICK* mentioned to the interviewer that for dessert they had eaten Brand X ice cream.
- The private party caterer had purchased pints of Brand X ice cream *CLICK* at the Franklin Retail location and brought it to the party. *PAUSE*
- P-value less than 0.05. A case-control study was conducted among the private party attendees. Meal items served included fresh vegetables, fruit, and various pastas. For dessert, vanilla, chocolate, and raspberry chocolate chip flavors of Brand X ice cream were available. *CLICK* The raspberry chocolate chip ice cream was eaten by all 5 cases asked about ice cream, 2 of 9 controls, and was significantly associated with illness. The party host had leftover vanilla and chocolate ice cream, which were picked up for testing.
- Overall, 15 cases were identified from the 4 venues. Meal dates ranged from August 4 at Restaurant A (shown in green) through August 14 at the Upton Retail location (shown in yellow). The median incubation period was 31.5 hours; one case was hospitalized. Eight cases, from all four venues, had a stool sample test positive for norovirus by realtime PCR. These cases are indicated by the black dots, including a Virginia resident who was generously tested by colleagues at the Virginia Department of Health.
- MDA inspectors visited Brand X Ice Cream Commissary Kitchen on August 16 to evaluate food preparation procedures for the raspberry chocolate chip ice cream, gather invoices, and gather employee contact information. The raspberry chocolate chip ingredients included a vanilla base mix, chocolate chips, frozen raspberries, sugar, and stabilizer. The vanilla base mix was used in all of the ice cream flavors. *CLICK* The frozen raspberries where used only in the raspberry chocolate chip flavor. The raspberries were thawed, mixed with sugar and stabilizer, and added to the ice cream. This process did not involve a kill step. Preparation of the ice cream was done by machine, and involved no direct food worker handling. All 16 employees at the commissary kitchen were interviewed by MDH’s Team Diarrhea and no recent gastrointestinal illnesses were reported.
- Website states: “handfuls of fresh picked West Coast raspberries…” *CLICK* On July 22, 13 days prior to the first case meal dates, a large shipment of frozen raspberries had been received at the commissary kitchen. *CLICK* This shipment included bags of raspberries sourced from Chile, Serbia, and China. The outbreak took place in the summer of 2016, but some of the raspberries in the freezer had been packaged and frozen in 2014. Unfortunately, the restaurant did not keep internal records of which berries had been used in ice cream produced after this shipment was received, so it was unknown which berries had been used in the suspected lots. This is what we would call a traceability nightmare. Not only is it bad for the public and for us as outbreak investigators, but it is a challenge for the production facility too.
- The commissary put the remaining berries in this shipment on hold in their deep freezer. Brand X initiated a product withdrawal *CLICK* of their raspberry chocolate chip flavor on August 16.
- The product withdrawal included return of all 2.5 gallon tubs of raspberry chocolate chip ice cream that had been distributed to Brand X’s two retail locations and other venues (including restaurants). By August 19th, 146 tubs had been returned to the commissary from the retail locations, in addition to tubs returned from restaurants. The Brand X retail locations also sell pints of any flavor that are scooped directly at the counter. Sales information from Brand X indicated that from July 1 through August 15 (when they stopped serving raspberry chocolate chip), 348 pints of ice cream of all flavors were scooped and sold at the retail locations. The raspberry chocolate chip was generally their 3rd most popular flavor. These data indicated that it was unlikely a substantial risk to the public from this ice cream remained and no consumer advisory was issued.
- On August 25, MDA collected samples for testing at the US Food and Drug Administration (FDA) laboratory in Maryland. Focused on raspberry chocolate chip ice cream prepared AFTER the receipt of the raspberry shipment (7/22/16) and BEFORE the last meal date reported (8/14/16) Ten 2.5 gallon containers of ice cream were collected, each with a different Julian date. Six bags of frozen raspberries were collected, two from each source country. Samples were shipped on dry ice to the CFSAN lab in Maryland in September 2016. Four (4) pints of vanilla and chocolate ice cream leftover from private party were also collected and included in the shipment.
- Both the vanilla and chocolate ice cream left over from the private party were found to be negative. But not surprisingly, a number of samples collected from the 10 2.5 gallon containers of raspberry chocolate chip ice cream tested positive for norovirus. *CLICK* However, while norovirus was not found in bags of frozen raspberries from Chile and Serbia, the Chinese raspberries tested positive for norovirus by FDA. Additional raspberries sourced from China were collected by FDA from Ice Cream X’s deep freezer and also tested positive for norovirus at the Office of Regulatory Science laboratory using a method for extraction of norovirus from soft fruit.
- In conclusion, this was an outbreak of norovirus gastroenteritis associated with commercially distributed ice cream produced using contaminated frozen raspberries sourced from China. As a result of the outbreak, the manufacturer has initiated a kill step for frozen raspberries that involves heating before adding to the ice cream.
- Frozen berries are a well-known vehicle for hepatitis A virus, and have been implicated in many norovirus outbreaks, particularly in Europe. To our knowledge, this is the first norovirus outbreak due to imported frozen berries documented in the United States. This outbreak was tough to find. Most norovirus outbreak-detection systems are venue-focused, and not very sensitive to commercially distributed vehicles, particularly retail products. Norovirus outbreaks due to commercially distributed food items are likely more common than we realize. Several system components were essential to detecting and solving this outbreak.
- German outbreak Frozen strawberries imported from China (2012) http://www.foodsafetynews.com/2014/02/report-largest-outbreak-in-german-history-caused-by-imported-strawberries/#.Wsifdozyvcs http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=20719 GI and GII (multiple genotypes) detected in berries. Contaminated water used in production suspected due to multiple norovirus types and scale of outbreak. “In response to this outbreak, recommendations in Germany for institutions catering for vulnerable populations (including schools and child care facilities) have been amended and now specifically include the advice to heat frozen berries [13]. Furthermore, from 1 January 2013, a European Union (EU) regulation requires 5% of consignments of frozen strawberries imported from China into the EU to be tested for norovirus [14].”
- L Tavoschi, et al. Eurosurveillance. FOOD-BORNE DISEASES ASSOCIATED WITH FROZEN BERRIES CONSUMPTION: A HISTORICAL PERSPECTIVE, EUROPEAN UNION, 1983 TO 2013 -- Others oyster-associated Food Safety Authority of Ireland – boil all imported, frozen berries for one minute (particularly at-risk populations)
- This outbreak investigation was the combined work of many partners.