Tag Archives: acute and communicable disease prevention

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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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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Salmonella Braenderup

Milk Crates, Cartons, & Jugs

Outbreak: Milk Crates, Cartons, & Jugs
Product: Milk Crates, Cartons, & Jugs
Investigation Start Date: 01/27/2010
Location: Roseburg, Oregon
Etiology: Salmonella Braenderup
Earliest known case onset date: 10/21/2009
Latest case onset date: 10/01/2010
Confirmed / Presumptive Case Counts: 25 / 0
Positive Samples (Food / Environmental): 15 / 500
Hospitalizations: 0
Death: 0
Outbreak Summary:
This outbreak illustrates the value of descriptive epidemiology and the virtue of epidemiologist persistence! Over a 12-month period during 2009–2010, a total of 25 infections by Salmonella Braenderup with matching PFGE patterns were reported—no more than 4 in any given month. After 3 scattered cases over 3 months, the investigation began with recognition of a 3-case cluster in a single Oregon county in January 2010. Extensive hypothesis-generating (“shotgun”) interviews were thereafter conducted as each case was recognized, but no obvious source emerged. In desperation, on July 26, 2010, Oregon’s epidemiologists gathered to review the available information. The descriptive epidemiology proved pivotal. Person: although cases ranged in age from 1 to 88 years, there was a predilection for children: median case age was 13 years. Place: cases resided in 9 contiguous Oregon counties—but none from the populous Portland metropolitan area. Time: the prolonged duration of the outbreak ruled out most perishable items. What food or other vehicle could jibe with this information?

At least 94% of cases affirmed consumption of milk—though pasteurized and of different labels. But Umpqua brand milk was known to be distributed predominantly south of the Portland area, and no other plausible hypothesis survived the analysis of the assembled epidemiologists.

Experts in the Oregon Department of Agriculture were able to confirm that the alternative milk brands reported by cases or served in the case children’s schools were, in fact, produced by Umpqua. With the epidemiologists, they visited the production facility and confirmed that the pasteurization process was in order: records indicated that the milk was heated, stored, and packaged appropriately, with no apparent opportunity for post-pasteurization contamination. But culture of 132 environmental specimens obtained at the facility yielded Salmonella Braenderup in five: one from a milk crate, three from sites on the crate’s conveyor system, and one from a floor drain. The crate washer was situated on the roof of the facility, open to birds and perhaps other wildlife.

The investigation tendered a surprising conclusion: the milk itself was never contaminated. Rather, the bacteria were on the milk crates, occasionally finding their way onto individual cartons, and, from perhaps one in 10,000 cartons, into someone’s mouth. This conclusion that the milk crates and cartons acted as fomites (fō’ mĭ tēz)—objects that can transfer infectious microorganisms to humans—explained the prolonged duration of the outbreak, the low attack rate, the case demographics, and the cases’ exposure histories. Finding the cause allowed for remediation and resumption of business for Umpqua: after closing for a week to sanitize and to rebuild its crate system, the plant resumed production, and the outbreak ended.

Details:
To read The Oregonian story by Lynn Terry about this outbreak, click here.

INTRODUCTION:
25 cases dribbled out from Oct 2009 to Oct 2010; eventually linked to product from Umpqua Dairy in Roseburg. Crate washer was contaminating milk crates and (in turn) the sealed containers (not the milk per se).

A SURPRISING TWIST:
Umpqua milk products produced at the Roseburg plant have been confirmed as this source of the 25-case, year-long outbreak.

In a surprising twist, however, it appears that the milk itself may NEVER have been contaminated. Rather, the weight of evidence suggested that the problem stemmed from external contamination of the milk cartons and jugs from an outdoor crate washer.

In other words, the containers were fomites, meaning that by most definitions this was not a "foodborne" outbreak. Milk crates used to move product around the plant and to distribute product to retailers around the state come back to the Roseburg plant, where they recycled up a conveyor line through an outdoor crate washer and thence were carried inside the plant where they were loaded with cartons of milk.

As the crates went through the washer, they were in effect being sprayed down with a solution of Salmonella Braenderup. Matching bacteria were recovered from the washer and multiple points downstream, including crates and external surfaces of sealed containers.

The plant was shut for 5 days while the crate washer was disassembled, cleaned, and rebuilt, and other parts of the plant were cleaned and sanitized. Crates were boiled. New sanitizer stations were added to reduce or eliminate the risk of external contamination of the crates when they are filled with product.

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Salmonella Rissen

Lian How White Pepper

Outbreak: Lian How White Pepper
Product: White Pepper
Investigation Start Date: 03/02/2009
Location: OR, CA, NV, WA
Etiology: Salmonella Rissen
Earliest known case onset date: 11/01/2008
Latest case onset date: 05/27/2009
Confirmed / Presumptive Case Counts: 87 / 0
Positive Samples (Food): 33
Hospitalizations: 8
Deaths: 0
Outbreak Summary:
Salmonella Rissen is a very rare serotype in the US. When Oregon, California, and Nevada all reported it within days of each other, it began a coordinated investigation between those states (later to be joined by Washington and Idaho). This outbreak focused FDA attention on the role spices may play in salmonellosis outbreaks. Additionally, a large proportion of cases either had urine isolates or no gastrointestinal symptoms, making interviewing about food histories much more complicated.
Details:
Background:
Salmonella Rissen is a very rare serotype in the U.S. with approximately 6 cases/year; in 2006 there was a sizable jump to 18 cases. Rissen is a fairly common serotype in Thailand, however; it is commonly associated with pork and chicken products.

On March 2, 2009, the Nevada State Public Health Laboratory posted a notification of a local cluster of Salmonella Rissen; CA and OR state health departments responded the same day to report similar local clusters—definitely above the expected annual baseline. In fact, this was the first reported outbreak of Salmonella Rissen in the United States. Washington and Idaho would later join the investigation with locally reported cases. CA and NV cases were clusters in the San Francisco Bay and Carson City/Reno areas, respectively.

Methods and Results:
By consensus, cases with an identifiable onset date were interviewed with shotgun questionnaires. CDC reported that the only PFGE match in the PulseNet database was an FDA report of an isolate from Vietnamese black peppercorns in 2006. Although the significance of this finding was uncertain, we were aware of it and added pepper-related questions in all interviews.

Oregon noted that they had one case who was Vietnamese and another who frequently ate at Vietnamese restaurants—fairly tenuous but about all we had to start with. An absence of travel histories implied a commercial product distributed primarily or exclusively in the West.

An extraordinary proportion of cases (63%) lacked what we could call a “clean” onset date—they either had vague symptoms going back for an indefinite period or had only urine isolates, sometimes with no referable GI symptoms.

Cases broke out into three distinct populations:

  • • Approximately half of the cases either had exposure to Asian restaurants or foods or had Asian surnames who cooked traditionally Asian foods at home (Generally younger and healthy)

  • • Cases exposed to same large casino buffet in Nevada (exposures occurred between 12/08-2/09)

  • • 35% of cases were hospitalized prior to or during time of specimen collection (generally older with underlying health conditions); they were at different facilities all under the same HMO organization
At least 18 hypothesis-generating interviews were conducted using a hybrid of the Oregon shotgun and other more open-ended questions to explore longer time periods and more vague food exposures. Instead of using the standard time period of 7 days to go back and assess foods consumed prior to illness, we expanded the question over weeks and sometimes months of time; so many cases had little or no GI symptoms we wanted to cast a wide net when asking about exposures.

Nothing strongly suggestive emerged from those analyses other than the obvious clustering of NV and CA cases who had visited and eaten at Casino A in Reno. Efforts to identify common foods there foundered on the combination of poor recall and all-you-can-eat buffet overload. Some product testing was attempted, but initial results were all negative, including black pepper. NV initially suspected cilantro to be the culprit and were waiting to get confirmation that a buffet reservation had contained it at an ingredient; the decision was made not to test the black and white ground pepper that had been collected from the buffet in the first round of testing. All buffet ingredients that were initially tested came back negative.

  • o Bean sprouts: 33% cases vs. 12% FoodNet;
  •     –OR 3.8, exact 95% CI 0.8-14.5, p=0.04
  •     –Cumulative (binomial) probability = 0.0154
  • o Cilantro: 55% cases vs. 35% FoodNet;
  •      –OR 2.3, exact 95% CI 0.6-9.5, p=0.20
  •      –Cumulative (binomial) probability = .0597
  • o Black pepper: 67% cases, no FoodNet data available
Oregon decided to pursue brute force testing at two different restaurants frequented by one case (i.e., not really “implicated” in any way). This case had a urine isolate of Salmonella Rissen that was tested as follow up to a urinary tract infection and only reported one instance of loose stools (i.e., diarrhea); the case ate the named restaurant in the 3 days before illness. Food and spice samples were collected and split between IEH Laboratories in Seattle and the Oregon State Public Health Laboratory. Both labs isolated Salmonella Rissen from an open 5# container of Lian How brand white pepper collected at a Chinese/Vietnamese restaurant where the case added white pepper from a shaker into Phở (Vietnamese noodle soup). The Oregon PHL also recovered Rissen from a similar and adjacent container of black pepper.

California Food and Drug Branch and the FDA worked with Union International Food Co. (Union City CA), which quickly led to a “voluntary” recall of Lian How and Uncle Chen brand pepper products on March 30, 2009—and soon expanded include everything that they packaged or prepared because of gross environmental contamination with Salmonella.

We worked with local and ODA environmental health staff to trace product distribution in Oregon and to reach out to restaurant operators who may have received the product. Language barriers and other considerations made us chary of relying solely on the media or the efforts of product distributors.

The final official tally was 87 cases in OR, WA, ID, NV, and CA; eight of the cases were Oregon residents. Clean onset dates occurred between 12/09/2008 and 04/29/2009 and could only be establish for 32 (37%) of cases. Rissen was isolated from stool specimen in 54% of the cases and from urine specimen in 39% of the cases. Ages ranged from 5 months to 94 years old with a median of 52 years old. Females accounted for 64% of the cases. Eight people were hospitalized due to GI illness (in all states).

Quantitative testing of three white pepper samples (recovered from 3 different Oregon restaurants) was performed by IEH Laboratories; results were 14 MPN/g, 2,400 MPN/g, and 14,900 MPN/g.

Conclusions
Contaminated white pepper was the cause of this outbreak. The positive black pepper sample was never replicated at any other lab and may have resulted from cross-contamination (most likely at the restaurant).

This outbreak (and the later Daniele salami outbreak) has focused FDA attention on the role spices may play in salmonellosis outbreaks; there are ongoing efforts in this arena.
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e-coli-o157

Bagged Spinach

Outbreak: Bagged Spinach
Product: Spinach
Investigation Start Date: 09/08/2006
Location: Multi-State
Etiology: E. coli (STEC) O157:H7
Earliest known case onset date: 08/25/2006
Latest case onset date: 09/13/2006
Confirmed / Presumptive Case Counts: 5 / 0
Positive Samples (Food / Environmental): 0 / 0
Hospitalizations: 98
Deaths: 3
Outbreak Summary:
This outbreak highlighted Inter-state health department cooperation. Oregon epidemiologists identified that 4 out of 5 cases in Oregon consumed bagged spinach using their homegrown "Shotgun" hypothesis-generating questionnaire. Contact with WI and NM showed cases already underway with spinach showing signs of being the culprit. Contact with Utah allowed them to quickly re-interview on spinach. The rest played out nationally following a conference call with NM, UT, OR, CDC, and FDA. FDA went public later that day.

Details:
Multi-state outbreak linked to bagged spinach, Dole and others from Natural Selections, Calif.

On Friday, 8 Sept 2006, ~1800, Janie called to report 3 that we had a match of 3 O157s, including 1 from Cowlitz Co. We had 1 form in hand already (GW), so we contacted Debby Uri at home to get the story on her case and attempted to reach Cowlitz Co on-call people. The Linn Co person had been in Idaho the whole exposure period, and presumably was exposed there. GW worked at a hospital in Oregon, but had no contact with any known O157 cases. The Washington guy had been in Oregon only briefly during during the 10 d before onset. His father visiting from Florida had also been ill but no MD. We agreed to pursue jointly on Monday.

Late Tuesday afternoon (again around 1800) Janie reported 2 additional matches, so Melissa took over the task of shotgunning these people. She called until late Tuesday night, and finished Wed morning. The only surprising finding was 4/5 reporting eating bagged spinach, vs. an estimated background for ANY spinach of 17% (P = 0.0036). [Testing months later showed the non-spinach eater to have a different MLVA type.] She had a mix of brands being reported, although 3/5 said they shopped at Winco. Around noon she left to have lunch with a friend and was going to swing by Winco to get sample bags.

Soon after she left I decided to notify CDC that we had a probable hit on this cluster, and to find out if there were any other clusters around the US. Our lab had been unable to upload the patterns because their CDC “fob” had expired, and we were temporarily cut off from the PulseNet data exchange. I sent Chris Braden the picture of the PFGE, and he quickly responded that it appeared by eye to match cases in WI, NM, and UT that were under investigation. He said that WI suspected some kind of fresh produce—possibly based on their demographic profile alone, at which point I emailed that we suspected bagged spinach specifically. (In the earlier message I had said we had a tentative
product, but didn’t say what it was. All these exchanges happened within 15-20 minutes). I followed up the 2nd email with a phone call, and he connected us to WI (Jeff Davis and John Archer at least), who had ~17 cases already and were underway with a c-c study.

At that point they had 8 case interviews only, but all 8 had eaten spinach, which for me certainly iced the cake. After that call ended I contacted Utah and NM (not vv as stated in the MMWR). Utah did not have spinach on the Q they were using, but agreed to quickly re-interview on spinach. NM was already interested in spinach from their interviews, and was already trying to collect leftover spinach from 1 hh. During that phone call I got a voice mail from Marilee Poulson that their cases were all reporting bagged spinach consumption.

That is about the end of it. The rest played out nationally following a conference call with NM, UT, OR, CDC, and FDA Thursday morning (14 Sept). FDA went public later that day.

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