| Outbreak: Venison Jerky |
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| 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: |
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| 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. |
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| 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. |
| Outbreak: Foundation Farm Raw Milk |
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| 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: |
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| 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. |
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| 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. |
| Outbreak: Berry Stand Strawberries |
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| 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: |
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| 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. |
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| 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. |
| Outbreak: Milk Crates, Cartons, & Jugs |
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| 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: |
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| 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. |
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| 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. |
| Outbreak: Lian How White Pepper |
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| 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: |
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| 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. |
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| 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:
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.
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. |
| Outbreak: Bagged Spinach |
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| 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: |
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| 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. |
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| 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. |
| Outbreak: #1984-001 |
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| Product: Restaurant salad bars |
| Investigation Start Date: 1985 |
| Location: Waso County, Oregon |
| Etiology: Salmonella Typhimurium |
| Earliest known case onset date: 9/9/1985 |
| Latest case onset date: 10/10/1985 |
| Presumptive / Confirmed Case Count: 0 / 751 |
| Positive Samples (Food / Environmental): 0 / 0 |
| Outbreak Summary: |
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| The 1984 Rajneesh salmonella outbreak was the single largest bioterrorist attack in United States history. Featured: the two-part presentation on the Oregon Health Authority investigation. |
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| A leading group of followers of Bhagwan Shree Rajneesh (later known as Osho) had hoped to incapacitate the voting population of the city so that their own candidates would win the 1984 Wasco County elections. The incident was the first and single largest bio-terrorist attack in United States history. The attack is one of only two confirmed terrorist uses of biological weapons to harm humans since 1945. 751 people contracted salmonellosis as a result of the attack; 45 of them were hospitalized. There were no fatalities. Although an initial investigation by the Oregon Public Health Division and the Centers for Disease Control did not rule out deliberate contamination, the agents and fact of contamination were only discovered a year later. On February 28, 1985, Congressman James H. Weaver gave a speech in the United States House of Representatives in which he "accused the Rajneeshees of sprinkling salmonella culture on salad bar ingredients in eight restaurants". At a press conference in September 1985, Rajneesh accused several of his followers of participation in this and other crimes, including an aborted plan in 1985 to assassinate a United States Attorney, and he asked State and Federal authorities to investigate. Oregon Attorney General David B. Frohnmayer set up an Interagency Task Force, composed of Oregon State Police and the Federal Bureau of Investigation, and executed search warrants in Rajneeshpuram. A sample of bacteria matching the contaminant that had sickened the town residents was found in a Rajneeshpuram medical laboratory. Two leading Rajneeshpuram officials were convicted on charges of attempted murder and served 29 months of 20-year sentences in a minimum-security federal prison. |
| Outbreak: Paramount & Raw Almonds |
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| Product: Almonds |
| Investigation Start Date: 02/23/2004 |
| Location: Multi-state outbreak |
| Etiology: Salmonella Enteritidis |
| Earliest known case onset date: 02/01/2004 |
| Latest case onset date: 04/17/04 |
| Confirmed / Presumptive Case Counts: 7 / 0 |
| Positive Samples (Food / Environmental): 1 / Lots |
| Hospitalizations: 7 |
| Deaths: 0 |
| Outbreak Summary: |
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| This investigation was rapidly solved by the use of Oregon's "Shotgun" hypothesis-generating questionnaire, a detailed food history interview tool that asks about over 400 different foods and places to eat. A single interviewer at the Oregon state health department used this standardized questionnaire to interview all 5 of the first cases detected as part of the same outbreak. Though the questionnaire only asked about "almonds in the shell," when the first two cases recalled eating raw almonds the interviewer took an iterative approach and modified the questions she asked the next 3 cases to include raw almonds. |
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| Outbreak of Salmonella Serotype Enteritidis Infections Associated with Raw Almonds — United States and Canada, 2003–2004 On June 4, this report was posted as an MMWR Dispatch on the MMWR website: (http://www.cdc.gov/mmwr). On May 12, 2004, the Oregon State Public Health Laboratory identified a cluster of five patients infected with Salmonella enterica serotype Enteritidis (SE) isolates that were matched by using two-enzyme pulsed-field gel electrophoresis (PFGE). The five patients were from four Oregon counties; their onsets of illness occurred during February–April 2004. A subsequent investigation, still ongoing, has identified a total of 29 patients in 12 states and Canada with matching SE isolates, since at least September 2003. Seven patients have been hospitalized; no one has died. Raw almonds distributed throughout the United States and internationally have been implicated as the source of the SE infections. As of May 21, approximately 13 million pounds of raw almonds had been recalled by the producer. Routine interviews of the initial five patients with salmonellosis had not indicated a common exposure. However, prompted by the May 12 laboratory data, the patients were reinterviewed by using a standard hypothesis–generating questionnaire that included questions about consumption of approximately 400 specific food items and their shopping and eating venues during the 5 days before illness onset. Using binomial distribution, consumption rates for selected foods were compared with background rates estimated from a 2002– 2003 population-based survey of residents of Oregon (1). The initial five patients from Oregon all reported consuming Kirkland Signature brand raw almonds, purchased at Costco warehouse stores. Survey data (1) indicated that an estimated 9% of Oregon residents (86 of 921 surveyed) consumed raw almonds from any source in the preceding week. Even assuming that 20% of all Oregon residents ate Kirkland Signature brand raw almonds each week, the binomial probability of finding five of five sporadic cases with that history is <0.001. No other foods or food sources were associated with illness. After determining that the raw almonds were distributed widely, U.S. and Canadian epidemiologists and state and federal regulatory agencies were notified on May 13 via electronic information networks. Through PulseNet, the national molecular subtyping network (2), laboratories were queried for reports of isolates matching the outbreak PFGE patterns (XbaI: JEGX01.0049; BlnI: JEGA26.0008 or JEGA26.0009, reflecting minor variation later observed with the second enzyme). Laboratories that did not routinely screen SE isolates by using PFGE were encouraged to do so for isolates collected since February 1, 2004. Phage typing was performed by standard methods. As additional PFGE-matching isolates were identified, a brief, customized questionnaire was used in interviews with persons about their nut consumption. Raw almonds from an opened package recovered from one patient’s household were tested for Salmonella by enzyme immunoassay. Unopened packages of nuts from the supplier’s warehouse and environmental samples collected at the almond processor and at huller-shellers supplying the processor were tested for Salmonella by using standard microbiologic methods. As of June 2, a total of 29 patients with SE infections matching both XbaI and BlnI PFGE patterns had been identified in 12 states and one Canadian province. Symptom onsets ranged from September 2003 to April 2004 (Figure). Patients ranged in age from 11 months to 91 years (median: 40 years); 17 (59%) were female. Seven patients were hospitalized; no one died. Multiple other cases with matching PFGE patterns and onsets earlier in 2003 remain under review. To date, nine isolates from the current outbreak have been phage typed; all are type 9c, which is uncommon. Among 26 patients interviewed, 24 recalled eating raw almonds during the week before illness onset; 20 patients identified brands packaged or supplied by Paramount Farms (Lost Hills, California). One infant patient was presumed secondarily infected. Through retailer computer records linked to membership cards or customer receipts, dates and places of almond purchase were verified for 10 households of patients. The dates of verified almond purchases ranged from November 3, 2003, to January 28, 2004. Efforts to identify specific production lots associated with illness, based on almond purchase dates and locations and store inventory data, are ongoing. On May 18, Paramount announced a nationwide recall* of all raw almonds sold under the Kirkland Signature, Trader Joe’s, and Sunkist labels. Costco mailed 1,107,552 letters to members known to have purchased the recalled product in the United States. The recall was expanded subsequently to include nuts sold in bulk to approximately 50 other commercial customers, some of whom repackaged almonds for sale under other brand names. In addition to sales in the United States, almonds were exported to France, Italy, Japan, Korea, Malaysia, Mexico, Taiwan, the United Kingdom. The majority of the recalled almonds likely were consumed months ago; however, raw almonds have a shelf life of >1 year, and consumers might still have the implicated products. Tests of raw almonds recovered from a patient’s household and samples collected at Paramount were negative for Salmonella; however, Salmonella was isolated from one environmental sample collected at Paramount and from three samples from two huller-shellers that supplied Paramount during the period of interest. Serotype and PFGE analyses of these isolates have not been completed, and additional sampling continues. |
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