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Shigella

Protected: Spiritual Retreat Shigella

Outbreak: Lighthouse Retreat Shigella
Product: Never pinpointed
Investigation Start Date: 7/28/2005
Location: Douglas County, OR
Etiology: Shigella
Earliest known case onset date: 07/19/2005
Latest case onset date: 08/06/2005
Confirmed / Presumptive Case Counts: 18 / 262
Positive Samples (Food / Environmental): 0 / 0
Outbreak Summary:
This outbreak of shigellosis is one the largest Oregon has ever seen with at least 280 cases identified (18 of which were lab-confirmed).
Details:
A local organic farm and meditation retreat center hosted its annual 16-day retreat in 2005; the ill were among 1,400 people from 38 states and 21 foreign countries who converged on the center between July 22 and August 7. Daily attendance was ~750 people but this fluctuated with people coming and going. Most visitors had been staying for 1 to 4 weeks.

The even was organized and executed by volunteers and 20 permanent staff members. Though this is a farm, no animals were kept on site. The group meals (only vegetarian) were prepared in one of two kitchens and consumed in a barn converted into a mess hall. Group meetings and meditation, as well as volunteer work, happened multiple times each day. Attendees camp or bunk on site and there were 55 portable toilets and sinks brought in for the event.

We identified 280 persons who met the case definition for shigellosis; 250 saw a clinician and 9 were hospitalized. Many had come from around the world and made closing the camping areas seem like a poor option.

Water samples were collected and did not yield positive results; food samples were not available for testing. The source of the outbreak was not found; it is likely that a human carrier working in the food prep or serving area contaminated some food items, which led to point source spikes in the epi curve (“simultaneous” infection, following one or two meals). Once Shigella seeded into this temporary community, it spread through a person-to-person route; difficult hygiene conditions at the center made this a plausible scenario. Putting disease control measures rapidly into place was critical for stopping the outbreak at this mass gathering event.
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salmonella-typhimurium

Cold Stone

Outbreak: Cold Stone Cake Batter Ice Cream
Product: Cake Batter Ice Cream
Investigation Start Date: 06/29/2005
Location: Multi-state
Etiology: Salmonella Typhimurium
Earliest known case onset date: 05/21/2005
Latest case onset date: 07/04/2005
Confirmed / Presumptive Case Counts: 25 / 0
Positive Samples (Food): 2
Outbreak Summary:
The vehicle for this outbreak was ice cream made with a contaminated cake mix ingredient. Four patients reported eating cake batter flavor ice cream from two separate outlets of Cold Stone Creamery.
Details:
Salmonella Typhimurium Outbreak Associated with Cake Batter Ice Cream from Cold Stone Creamery

Background
On June 29, 2005, the Minnesota Department of Health identified four Salmonella Typhimurium isolates with a pulsed-field gel electrophoresis (PFGE) subtype that was new to the PulseNet national database. Four patients reported eating cake batter flavor ice cream from two separate outlets of Cold Stone Creamery.

Methods
The PulseNet national database was queried to identify potential cases in other states. A case was defined as infection with an S. Typhimurium isolate that matched the outbreak PFGE pattern, and illness onset since May 2005. All cases were interviewed with a standard questionnaire. State and federal officials conducted a traceback of ice cream ingredients.

Results
We identified 25 cases in nine states (MN, 5; OR, 5; WA, 5; VA, 3; OH, 2; CA, IL, MA, MI, PA, 1 each); 24 reported eating cake batter ice cream from Chain A. The median age of cases was 13years (range, 2–32 years). The median incubation was 4 days (range, 1–7 days). Illness onset dates ranged from May 21 to July 4; four cases were hospitalized. Cold Stone Creamery voluntarily recalled cake batter ice cream on July 1. This flavor’s ingredients included a pasteurized liquid sweet cream base and Gold Medal Super Moist yellow cake mix. The sweet cream base was used in numerous other ice cream flavors, but the cake mix was used only in cake batter ice cream. The cake mix comprised spray-dried egg whites, flour, and several low-risk components. Tracebacks in Minnesota, Oregon, and Virginia implicated a single lot of cake mix produced on April 14, 2005. No manufacturing anomalies were identified for this lot; but two cake mix samples yielded the outbreak strain of S. Typhimurium. The Food and Drug Administration warned food retailers that cake mixes and flour are not considered “ready to eat” and should be heat processed before consumption.

Conclusion
The vehicle for this outbreak was ice cream made with a contaminated cake mix ingredient. While the ultimate source of contamination was not confirmed, we recommend a review of the efficacy of spray-drying egg whites as a kill step for Salmonella. Routine and rapid subtyping of bacterial isolates, coupled with a vigorous epidemiological response, is critical to identifying and abating multi-state outbreaks.
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e-coli-o157

Jack In The Box

Outbreak: Jack In The Box Hamburgers
Product: Hamburgers
Investigation Start Date: 01/12/1993
Location: Multi-State Outbreak
Etiology: E. coli O157
Earliest known case onset date: 11/18/1992
Latest case onset date: 02/21/1993
Confirmed / Presumptive Case Counts: 503 / 229
Positive Samples (Food / Environmental): 0 / 0
Hospitalizations: 151
Deaths: 3
Outbreak Summary:
This was the largest outbreak of E. coli O157 infections ever documented in the United States, and it injected this pathogen—and threats to food safety in general—into popular consciousness.
Details:
On January 12, 1993, a pediatric gastroenterologist notified the Washington State Department of Health (WSDOH) of an increase in emergency department visits for bloody diarrhea and the hospitalization of three children with hemolytic uremic syndrome.

Hypothesis-generating interviews suggested exposure at Jack In The Box restaurants, and in a swiftly conducted matched case-control study WSDOH confirmed association of illness with Jack-in-the-Box hamburgers.

After news of the Seattle outbreak broke, clusters of bloody diarrhea and lab-confirmed E. coli O157 infections were soon recognized as associated with Jack In The Box hamburgers in California, Nevada and Idaho — an association confirmed by molecular testing by the newly developed Pulsed-Field Gel Electrophoresis (PFGE)method.

Observation of cooking methods revealed that hamburgers did not consistently reach internal temperatures lethal for E. coli. Product trace-backs implicated selected lots of hamburgers (picture); culture of uncooked hamburger patties corroborated the epidemiologic findings. (1)

Several pivotal public-health initiatives were undertaken in this outbreak's wake:

1. At the time of the outbreak, E. coli O157 infection was reportable in only 12 states. By the end of 1994, 33 states had made it reportable, and by the end of 1996, it was reportable in all but 6 states.

2. The outbreak "broke" the weekend of Bill Clinton's first Presidential inauguration, and it was one of the first exigencies that faced the new administration. Agriculture Secretary Mike Espy proposed sweeping changes to existing regulations regarding beef production, which had required only visual inspection of beef-processing operations. Under the new rules, USDA began testing samples of raw ground beef in 1994 for E. coli O157, which was declared an "adulterant," indicating a zero-tolerance policy for its presence even in uncooked beef; and in 1996 required the risk-reduction system known as "Hazard Analysis & Critical Control Points" (HACCP) in meat-processing establishments.

3. A renewed emphasis on foodborne illness was undertaken at CDC. In 1995, "FoodNet" was initiated to capture detailed data regarding foodborne illnesses systematically and to conduct special studies into their sources. Today, food safety has public health prominence as one of CDC's "Winnable Battles."

4. The Jack In The Box outbreak was the first major use of PFGE -- a new DNA typing technique that could explore relatedness of bacterial isolates. CDC trained and funded state health departments to test bacterial isolates routinely using this method and to report to a centralized system, where widespread but low-level outbreaks could be detected. Today, this "PulseNet" system can be credited with detecting a substantial fraction of recognized foodborne outbreaks.

References: 1. Tuttle et al. "Lessons from a large outbreak of Escherichia coli O157:H7 infections: insights into the infectious dose and method of widespread contamination of hamburger patties."
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norovirus

Frozen Oysters

Outbreak: Frozen Oysters
Product: Frozen Oysters
Investigation Start Date: 11/22/2006
Location: Marion County, OR
Etiology: Norovirus GI
Earliest known case onset date: 11/15/2006
Latest case onset date: 11/17/2006
Confirmed / Presumptive Case Counts: 2 / 11
Positive Samples (Food): 1
Outbreak Summary:
A rapid investigation of a Norovirus outbreak implicated commercially frozen oysters on the half shell that were thawed and served raw. Over 25,000 pounds of product from the same lot was embargoed by the FDA, which was then considering further restrictions on this type of product, which had been imported from Korea.
Details:
Background
On November 22, 2006, an infection control nurse notified the Marion County Health department about acute gastroenteritis among persons who attended a reception at a medical facility on November 16, 2006, and began at 6:00pm. The county asked the state health department to join the outbreak investigation.

Methods
After interviewing the caterer, organizers, and several attendees, we modified a questionnaire template to reflect potential exposures. This questionnaire was used in a retrospective cohort study among reception attendees identified from a ticket list of approximately 200 persons. The epidemiologists were able to sample 66 attendees from 50 households.

Results
Ten persons met the case definitions of acute gastroenteritis, 53 had no symptoms, and three were excluded due to minor symptoms. Acute gastroenteritis cases were defined as reported vomiting or ≥ 3 loose stools within a 24 hour period within 18–72 hours of the event.

The median incubation period was 36 hours (range, 31–63 hours). Two stool samples were obtained, and both tested positive for norovirus (1 positive for genogroup II and 1 positive for both I and II). Illness was associated with consumption of raw oyster on the half shell, which was reported by 9 of the 10 cases (RR 11.8; 95%CI 2.8–50; p=0.0001). No other foods were associated with illness.

The oysters had been individually quick frozen on the half shell and packed loosely in cartons after being harvested in South Korea by growers approved by the US Food and Drug Administration. The oysters are pressure-treated to crack the shell, and then blast-frozen on the half shell in trays with a plastic seal over each tray. These oysters were packed in cardboard cartons—144 oysters with a net weight of 6-kg per box. For the reception, a single 6-kg box of oysters was thawed and served raw. The box was from a shipment of 2,200 boxes legally imported in October 2006. Boxes from the same shipment had been distributed to 5 states. No similar outbreaks were reported in the other states that got oysters from the same lot, though case-finding efforts vary. FDA tested oysters from the implicated lot and found Norovirus.

Lessons learned/historical significance
Although most reported foodborne norovirus outbreaks may stem from ill food handlers, it is important to rule out contaminated foods as the source of illness.

Because thorough outbreak investigations are time-consuming and gastroenteritis outbreaks are common, resource considerations often affect decisions about how intensively to pursue investigations. Oregon’s use of integrated questionnaire, data entry, and analysis templates facilitated a quick and successful response to the outbreak described here. Questionnaire design, interviews, data entry, and analysis were completed within 6 hours of the initial report, and distributors and regulatory agencies quickly recalled other oysters from the same source, probably preventing additional illnesses. Widespread use of such templates may increase the number of outbreaks that could be investigated thoroughly.
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Uncategorized

2010-023 Article

Milk output resumes after odd outbreak

Umpqua Dairy | The Roseburg plant is cleaned and sanitized to be free of salmonella
By LYNNE TERRY
THE OREGONIAN Umpqua Dairy resumed milk production in Roseburg on Wednesday after a statewide salmonella outbreak that took scientists months to solve in a case that still remains a bit of a mystery. The plant was cleaned … Continue Reading ››
norovirus

Cholo’s Mexican Restaurant, Oahu

Outbreak: Oahu Norovirus
Product: Cholo's Mexican Restaurant
Location: North Shore of Oahu, Hawaii
Etiology: Norovirus
Confirmed / Presumptive Case Counts: 10 / 80
Earliest known case onset date: 04/08/2011
Latest case onset date: 04/11/2011
Outbreak Summary
Still need an outbreak summary.
Cholo’s is a popular (and generally good) Mexican restaurant up on the North Shore of Oahu, the most populous island in Hawaii.

Unfortunately for them, though, they apparently had some workers who had norovirus infection and proceeded to contaminate the food they prepared.

The outbreak was picked up via participants of a century (bike) ride who ate at the restaurant after their event, got sick, and reported their illness to us.

We subsequently identified at least 80 individuals who had consumed food at the restaurant from April 8–10, 2011. Stools from about 10 of them were positive for norovirus.

The restaurant engaged in extensive cleaning and education of their workers and was able to continue operations afterward.
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About the Museum

Welcome to the Museum

The International Outbreak Museum was founded by Dr. William Keene, who passed away in December, 2013. The museum is housed in the Portland State Office Building in Portland, Oregon.  The museum is part of The Northwest Center for Foodborne Outbreak Management, Epidemiology, and Surveillance (FOMES).  It is made possible by the Acute and Communicable Disease Prevention Section, which … Continue Reading ››
e-coli-o157

Venison Jerky

Outbreak: Venison Jerky
Product: Venison Jerky
Investigation Start Date: 11/20/1995
Location: Benton County, Oregon
Etiology: E. coli (STEC) O157:H7
Earliest known case onset date: 11/13/1995
Latest case onset date: 11/20/1995
Confirmed / Presumptive Case Counts: 6 / 5
Positive Samples (Food / Environmental): 2 / 2
Outbreak Summary:
At a time when ground beef was thought to be the source of all foodborne E. coli O157 infections, this was the first documentation of venison-associated E. coli O157:H7 outbreak. Epidemiologists showed that deer can be colonized by E. coli O157:H7 and ultimately be a source of human infections. Game should be handled with the same caution indicated for commercially slaughtered meat, and jerky dehydration does not reliably kill bacteria in meat.
Details:
The following is the abstract from the published article found here.

OBJECTIVE:
To investigate a 1995 outbreak of Escherichia coli O157:H7 infections and to assess the safety of meat dehydration methods.

DESIGN:
Survey subsequent to routine surveillance report, environmental investigations, and laboratory experimentation.

SETTING:
Oregon community.

PARTICIPANTS:
Members of an extended household and their social contacts with confirmed or presumptive E coli O157:H7 infections.

RESULTS:
A total of 6 confirmed and 5 presumptive cases were identified. Homemade venison jerky was implicated as the source of transmission. E coli O157:H7 with the same distinctive, pulsed-field gel electrophoresis pattern seen in the case isolates was recovered from leftover jerky, uncooked meat from the same deer, a saw used to dismember the carcass, and fragments of the deer hide.
In a subsequent survey, E coli O157:H7 was recovered from 3 (9%) of 32 deer fecal pellets collected in nearby forest land. In the laboratory, inoculated venison was dried at several time and temperature combinations, ranging up to 10 hours at 62.8 degrees C. Viable organisms were recovered under all conditions tested.

CONCLUSIONS:
Deer can be colonized by E coli O157:H7 and can be a source of human infections. Conditions necessary to ensure the safety of dried meat deserve further review. Game should be handled with the same caution indicated for commercially slaughtered meat.
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e-coli-o157

Foundation Farm Raw Milk

Outbreak: Foundation Farm Raw Milk
Product: Foundation Farm Raw Milk
Investigation Start Date: 04/10/2012
Location: Clackamas, Mult., Wash. Counties, OR
Etiology: E. coli (STEC) O157:H7
Earliest known case onset date: 04/01/2012
Latest case onset date: 04/14/2012
Confirmed / Presumptive Case Counts: 11 / 5
Positive Samples (Food / Environmental): 2 / 13
Hospitalizations: 4
Deaths: 0

Outbreak Summary:
This outbreak highlighted the persistent hazard of raw milk consumption, already well documented in the medical literature. Four persons were hospitalized — some critically ill and all with hemolytic-uremic syndrome, subsequently shown to have been caused by E. coli O157:H7. Although most sales of raw milk are illegal in Oregon, the farm implicated here is an example of one method by which those determined to get the product can skirt the law: instead of “purchasing milk,” families bought “shares” in Foundation Farm cows, their dividends being the milk produced by them and then consumed without pasteurization.

The cause of the outbreak wasn’t long a mystery: Oregon public health nurses routinely interview each O157 case and ask about “usual suspect” exposures — one of which is whether the case consumed unpasteurized milk. A single case having a high-risk exposure like this one is sufficient to raise suspicion and to warrant further investigation. As the investigation progressed, it transpired that the families that participated in this “cow-share” arrangement had been aware of many illnesses and communicating about them; and the dairy farmer had already advised the shareholders not to drink the milk. The farm ceased production, and several parents publicly advised the unwary not to serve unpurified milk to their children.

Details:
On April 10, 2012, Multnomah CHD was notified by a clinician about a 1 year-old child with HUS (culture pending; later shown to be O157:H7). The child attended a day-care center in Washington County and had a history of regular raw milk consumption, both of which indicated a need for public health follow-up.

Washington CHD investigated the child care setting and found nothing to suggest any other illness of significance there. Meanwhile, it was agreed that ACDP would contact ODA and discuss what we could do about the herd share operation that was reportedly the source of the raw milk. It was determined that this was operation (dba Foundation Farm) was ostensibly legal with 4 cows (3 in production) that was unlicensed, unregulated by, and unknown to ODA. (Dairies of this type are not required to be licensed or regulated.)

The Oregon Department of Agriculture contacted the farm owner to request a list of all customers of the farm; all needed to be contacted to look for potential illness.

On the morning of the 11th Mr Salyers sent ODA a spreadsheet listing the 48 household contacts for his customers, and gave ODA oral authorization to visit the premises and collect any specimens we wanted from the working part of the farm (but not the residence building). He also reported to ODA that, following his attempts to contact his customers through Facebook, he had learned of “several” additional illnesses. (He already knew about the index case). He also reported that he had voluntarily stopped distribution of milk (which turned into a permanent closure) and had recommended to his customers that they discard any available product.

On the afternoon of the 11th, while local and state health department staff attempted case finding among herd share households, a group from ACDP (Keene, Tourdjman, Buser, Poissant) met Jim Postlewait from ODA at the farm in Wilsonville. There were no family members apparent on the premises while we were there; Mr Salyers had told us that he would be away and he had asked us not to bother people in the house. We collected a convenience sample of 63 samples including rectal swabs on all 4 animals, surfaces in and around the milking parlor, and fecal pat samples from adjacent pastures. No milk was available at the farm for testing.

Over the subsequent days, we attempted to interview all households on the list using a standardized questionnaire that covered history of Foundation Farm milk consumption, several other possible food exposures, and diarrheal illness in household members. A press release was issued to warn the public about the risk and to stimulate reporting; one of the earliest identified cases was from a household that was not on the customer list. That child had consumed the milk while visiting a family friend.

Leftover raw milk samples were collected on April 12 and 13 from two shareholder households for testing.

Results:
Eventually we identified 11 lab-confirmed cases—including 1 Washington state resident who consumed milk when visiting family in Oregon—and 5 presumptive cases. Four other household members reported very mild concurrent diarrheal symptoms and were not counted
as cases. Four cases were hospitalized—all with HUS. Three cases were hospitalized for >25 days—one of them for ~60 days.

We were able to successfully interview 30 (62%) of 48 herd-share households, comprising 91 individuals. Numerous attempts were made to interview members of the other 18 households to no avail; some were contacted but refused to cooperate with the investigation. All 15 cases reported consumption of FF milk on one or usually multiple occasions. No other suggestive common exposures were identified.

The farm setup was described by ODA as fairly typical for a family farm. The layout was very poorly designed from a food safety perspective. The premises appeared to be dirty and difficult to maintain in a hygienic manner for food production. There were no facilities to rapidly chill milk. Although we did not see it (because it was in the garage of the home), milk bottles were allegedly stored in an ordinary (non-commercial) refrigerator.

Thirteen (21%) of 63 samples collected at Foundation Farm were positive for E. coli O157:H7, including 10 samples of animal manure; 2 cattle rectal swabs; and 1 swab of fencing at the milking station. One of two milk samples collected from customer households was also positive. All but one O157 cultures from cases, milk, and the farm were indistinguishable by 2-enzyme pulsed-field gel electrophoresis (PFGE); one case appeared to have an extra band on XbaI.

Conclusions:
The outbreak was caused by consumption of contaminated raw milk. Efforts should be continued to warn consumers about the risks of raw milk consumption, which can result in horrific illness and death.

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E. coli O157:H7

Berry Stand Strawberries

Outbreak: Berry Stand Strawberries
Product: Strawberries
Investigation Start Date: 08/03/2011
Location: Clackamas, Multnomah, Washington, Clatsop & Yamhill Counties, Oregon
Etiology: E. coli (STEC) O157:H7
Earliest known case onset date: 07/01/2011
Latest case onset date: 07/29/2011
Confirmed / Presumptive Case Counts: 14 / 11
Positive Samples (Food / Environmental): 4 / 100
Hospitalizations: 6
Deaths: 2
Outbreak Summary:
This investigation implicated a novel vehicle—strawberries—as the cause of an outbreak of E. coli O157 infections. An association with locally produced strawberries quickly became apparent as cases were interviewed; but the fact that almost all had purchased them at roadside stands and farmer’s markets led to concern about potential confounding of some overlooked item sold at similar venues. The concern was laid to rest by visits to the stands, a case-control study, and traceback of the strawberries to a single Oregon farmer. Learning how the strawberries became contaminated was the fruit of field work: epidemiologists investigated the strawberry fields and found them heavily contaminated with deer feces, with a herd of deer seen grazing in the area. Culture of 50 environmental samples that contained visible deer pellets yielded E. coli O157 in 10 (20%), with PFGE patterns matching those of the cases.

This outbreak once again confirmed deer as key reservoirs for the pathogen. Interestingly, an additional PFGE-matched case was identified months later; the case hadn’t eaten the commercial strawberries but lived in the area where they were grown. Culture of a sample from this case household’s vacuum cleaning bag yielded a PFGE-matching strain of E. coli O157:H7, a testimony to the pathogen’s ability to survive for prolonged periods when dried.

Details:
The following is the abstract from the published article found here.

Editorial commentary can be found here.

BACKGROUND:
An outbreak of Escherichia coli O157:H7 was identified in Oregon through an increase in Shiga toxin-producing E. coli cases with an indistinguishable, novel pulsed-field gel electrophoresis (PFGE) subtyping pattern.

METHODS:
We defined confirmed cases as persons from whom E. coli O157:H7 with the outbreak PFGE pattern was cultured during July–August 2011, and presumptive cases as persons having a household relationship with a case testing positive for E. coli O157:H7 and coincident diarrheal illness. We conducted an investigation that included structured hypothesis-generating interviews, a matched case-control study, and environmental and traceback investigations.

RESULTS:
We identified 15 cases. Six cases were hospitalized, including 4 with hemolytic uremic syndrome (HUS). Two cases with HUS died. Illness was significantly associated with strawberry consumption from roadside stands or farmers’ markets (matched odds ratio, 19.6; 95% confidence interval, 2.9–∞). A single farm was identified as the source of contaminated strawberries. Ten of 111 (9%) initial environmental samples from farm A were positive for E. coli O157:H7. All samples testing
positive for E. coli O157:H7 contained deer feces, and 5 tested farm fields had ≥ 1 sample positive with the outbreak PFGE pattern.

CONCLUSIONS:
The investigation identified fresh strawberries as a novel vehicle for E. coli O157:H7 infection, implicated deer feces as the source of contamination, and highlights problems concerning produce contamination by wildlife and regulatory exemptions for locally grown produce. A comprehensive hypothesis-generating questionnaire enabled rapid identification of the implicated product. Good agricultural practices are key barriers to wildlife fecal contamination of produce.

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