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Chicken Liver Campylobacter

Outbreak: Chicken Liver Campylobacter 
Product: Chicken LiversInvestigation Start Date: 1/10/2014
Location: Multi-StateEtiology: Campylobacter jejuni
Earliest known case onset date: 12/5/2013Latest case onset date: 12/24/2013
Confirmed/Presumptive Case Count: 4 / 2Positive Food Samples: 5

Six cases from three different states developed gastrointestinal illness after consuming under-cooked chicken livers. Most cases ate chicken liver made into pâté, but one case ate frozen raw chicken liver, based on her naturopath’s advice. All livers came from Draper Valley Farms in Washington State.


On January 8, 2014, the Ohio Department of Health notified the Oregon Public Health Division (OPHD) of Campylobacter jejuni infections in two Ohio residents recently returned from Oregon. The couple had visited a Multnomah county resident, who had also become ill with campylobacteriosis. The three reported having dined together at Heathman restaurant in Portland. The only food shared by all three was chicken liver pot de crème, a dish similar to liver pâté. Pâté is a spreadable paste made from cooked poultry livers blended with scallions, butter, salt, and other ingredients. All three cases became ill with vomiting and diarrhea within two hours of each other. On January 10, OPHD received additional reports of campylobacteriosis in two persons who had shared a chicken liver mousse appetizer at Wildwood restaurant in Portland. State epidemiologists launched an outbreak investigation.


In response to the reported illnesses, Multnomah County Environmental Health officials interviewed the restaurants to review food handling and preparation practices, and determine the source of the chicken livers served. Epidemiologists reached out to the Washington State Department of Health (WSDH) and discovered a recent case infected with C. jejuni who had eaten frozen, raw chicken livers as prescribed by a naturopathic doctor in the three days prior to illness onset. Using the reservation records from the Heathman, Oregon epidemiologists conducted a retrospective cohort study to find additional cases and to determine whether other foods could be causing illness. We reached 72 households whose residents ate at Heathman. In the households contacted, food histories were provided for 134 individuals.


The environmental health investigation revealed that both implicated restaurants undercooked the chicken livers they served, and both received livers from the same distributor. State epidemiologists visited the distributor and found they only carried chicken livers from Draper Valley Farms, a United States Department of Agriculture (USDA)-regulated facility in Washington State. Follow-up with the WSDH determined that their case also purchased her Draper Valley Farms chicken livers. Through the cohort study epidemiologists found seven individuals who reported having eaten chicken liver pot de crème at Heathman, one of which reported a campylobacteriosis-compatible illness (i.e., diarrhea lasting more than two days in the week after liver consumption). There was also one report of potentially compatible illness in a diner who did not report having eaten chicken livers. A presumptive case was defined as diarrhea lasting less than 2 days, within 7 days after consumption of undercooked chicken liver; a confirmed case was defined as laboratory evidence of C. jejuni infection within 7 days after consumption of undercooked chicken liver. Four laboratory-confirmed C. jejuni cases were reported in Ohio (1), Oregon (2), and Washington (1). Two presumptive cases were reported in Ohio (1) and Oregon (1). Only one human specimen from Oregon was available for subtyping at the Washington State Public Health Laboratory (WSPHL). Of nine Draper Valley liver samples tested for C jejuni, five were positive. Food samples culture positive for C. jejuni were sent to WSPHL for pulsed-field gel electrophoresis (PFGE) testing. The chicken liver samples from the Wildwood restaurant and the human specimen from the case that became ill after eating at Wildwood had indistinguishable PFGE patterns; no other PFGE patterns matched. Based on OPHD’s recommendation, both restaurants voluntarily stopped serving liver. Draper Valley Farms also reported they voluntarily stopped selling chicken livers.

Lessons Learned

Chicken livers are often contaminated with bacteria; if you’re going to eat them, make sure they are cooked thoroughly! In this outbreak, six cases of campylobacteriosis in Oregon, Washington, and Ohio were caused by consumption of undercooked chicken liver from a common supplier. No other common exposures were identified. A chicken liver sample and a human specimen had matching PFGE patterns. This is the second multistate outbreak of campylobacteriosis associated with consumption of undercooked chicken liver reported in the United States; in 2013 a similar outbreak occurred in Vermont. Chicken livers should be considered a risky food given the methods by which they are routinely prepared. Pâté made with chicken liver is often undercooked to preserve texture. It can be difficult to tell whether the livers in your pâté are cooked thoroughly because livers are often only partially cooked and then blended with other ingredients and chilled. A 2012 study found that 77 percent of chicken livers cultured were positive for Campylobacter. Washing chicken livers is insufficient to render them safe for consumption, as they can be contaminated internally and externally; therefore, cooking them to an internal temperature of 165°F is recommended.


  1. 1. CDC. Multistate outbreak of Campylobacter jejuni infections associated with undercooked chicken livers–northeastern United States, 2012. MMWR 2013;62:874-6.
  2. 2. Noormohamed A, Fakhr MK. Incidence and antimicrobial resistance profiling of Campylobacter in retail chicken livers and gizzards. Food Path Dis 2012;9:617-24.

Holiday Lunch Buffet

Outbreak: Holiday Lunch Buffet 
Product: Sliced Turkey MeatInvestigation Start Date: 12/10/2014
Location: Maitland, FloridaEtiology: Staphylococcus aureus & Bacillus cereus
Earliest known case onset date: 12/10/2014Latest case onset date: 12/11/2014
Confirmed/Presumptive Case Count: 6 / 135Positive Food Samples: 7
Hospitalizations: 8Deaths: 0

An outbreak of gastrointestinal illness, which sickened 141 persons, was caused by sliced turkey contaminated with Staphylococcus aureus enterotoxins served during a catered holiday lunch buffet at a multi-business office complex in Maitland, Florida on December 10, 2014. The outbreak, initially reported to the Florida Department of Health in Orange County via the Mass Casualty Incident Notification System, had an immediate media exposure that covered on-camera ill persons being taken to the hospital via ambulance from the business complex.

The investigation identified that the food was prepared by the caterer at a commissary in Seminole County and then transported to and served at the office complex in Orange County. As a result, several local and state responding agencies with jurisdiction were required to closely coordinate rapid public health investigative and public communication efforts. Unsanitary food preparation practices and several cycles of thermal abuse at multiple locations where the catered food was handled were readily identified during the environmental health investigation.

Six clinical specimens and four different foods cultured Staphylococcus aureus. Staphylococcus aureus enterotoxin Type A and Type C were identified in food samples. In addition, Bacillus cereus was cultured from one clinical specimen and five food samples, and one food sample tested positive for the hemolytic enterotoxin.


At 3:47 PM on Wednesday, December 10, 2014, the Florida Department of Health in Orange County (DOH-Orange) was notified of an outbreak of possible food poisoning by a broadcast on the Mass Casualty Incident Notification System. Approximately 25 individuals, who were experiencing severe nausea, vomiting, and diarrhea, were reported to have been taken by ambulance to area hospitals following a catered holiday lunch buffet at a multi-business office complex in Maitland, Florida, which is in Orange County. At 5:00 PM, DOH-Orange interviewed via phone Caterer A, who reported making the holiday lunch buffet food for 700 people at Commissary A, located in Seminole County. The service of food was split into two buffet lines in the indoor lobby of the office complex from 11:30 AM to 1:00 PM. The leftover food was then stored in the refrigerator of a restaurant located within the office complex. A multi-jurisdictional outbreak investigation was immediately begun involving two local and two state agencies. In addition, public information messages were coordinated across agencies to provide information to the media which began coverage of the outbreak even before all ill persons could be evaluated and transported to the hospital (media coverage).


Passive surveillance during the investigation was conducted to identify potentially associated cases using the Florida Department of Health syndromic surveillance system, ESSENCE-FL, foodborne illness complaints, and reportable disease investigations. The investigation used active surveillance via outreach to Orlando-area hospital infection control practitioners to assist in identification of persons associated with the outbreak and specimen collection and testing. The outbreak confirmed case definition was an individual who became ill with diarrhea or vomiting within 24 hours following consumption of food from a catered holiday lunch buffet at the office complex from 11:30 AM to 1:00 PM on December 10, 2014 and was positive for the presence of toxigenic bacteria. A presumptive case definition was an individual who became ill with diarrhea or vomiting within 24 hours following consumption of food from a catered holiday lunch buffet at the office complex from 11:30 AM to 1:00 PM on December 10, 2014. A questionnaire was developed to assist the investigation in assessing multiple hypotheses into the source of the outbreak, including unintentional and intentional contamination of food served at the holiday lunch buffet, and potential common exposures unrelated to the holiday lunch buffet. The questionnaire was administered via telephone, in-person visits, and self-administration from December 12 through December 19. A retrospective cohort study design was used and data analyses were performed using the information collected from the questionnaires using EPI INFO 7 and SAS software.

The caterer and servers were interviewed multiple times to determine environmental risk factors and antecedents surrounding the source of food items, methods of storage, preparation, transportation, and food service. Multi-disciplinary team of epidemiologists and environmental health specialists from multiple local and state agencies were involved in the assessment process that encompassed a caterer, commissary, restaurant, private residence, and a building complex. Historical regulatory inspection records for the commissary and caterer were obtained. Eleven stool specimens, one vomitus specimen, and thirteen trays of leftover food were sent to the DOH Bureau of Public Health Laboratories (BPHL) and Centers for Disease Control and Prevention (CDC) for laboratory analysis, including culture and bacterial enterotoxin testing.


The caterer and servers were interviewed multiple times to determine environmental risk factors and antecedents surrounding the source of food items, methods of storage, preparation, transportation, and food service. Multi-disciplinary team of epidemiologists and environmental health specialists from multiple local and state agencies were involved in the assessment process that encompassed a caterer, commissary, restaurant, private residence, and a building complex. Historical regulatory inspection records for the commissary and caterer were obtained. Eleven stool specimens, one vomitus specimen, and thirteen trays of leftover food were sent to the DOH Bureau of Public Health Laboratories (BPHL) and Centers for Disease Control and Prevention (CDC) for laboratory analysis, including culture and bacterial enterotoxin testing. A total of 141 (40%) of 349 persons interviewed from 15 businesses reported symptoms matching the case definition. Frequently reported symptoms consisted of watery diarrhea (87%), abdominal cramps (77%), and nausea (77%). Among those ill, eight (6%) people were hospitalized. No deaths were reported. The first onset of illness among study participants was at 12:45 PM on December 10, 2014; the last onset of illness was at 12:00 PM on December 11, 2014 (Figure 1).

The incubation period ranged from 22 minutes to 23.5 hours with a median of 4.3 hours. The duration of illness ranged from 1-103 hours with a median of 22 hours. No commonalities beyond consumption of food at the holiday lunch buffet where identified that could explain the observed illnesses. The incubation period did not statistically differ and symptomology were similar between the different buffet lines. Attack rate by business did not provide further insight into the cause of the outbreak.Food items that had a statistically significant risk at the 95 percent confidence interval for becoming ill with gastrointestinal illness are as follows (from Table 1):

  • •White turkey meat (RR (95%CI): 2.76 (1.58-4.80))
  • •Gravy (RR (95%CI): 1.88 (1.24-2.84))
  • •Devil chocolate cake (RR (95%CI): 1.44 (1.10-1.89)

With 36 (26 percent) study participants who became ill reporting consumption of the devil chocolate cake, this food item by itself was not determined to have caused the outbreak. Risk ratio calculations of implicated food items stratified by buffet line observed that only white turkey meat was statistically significant for being associated with illness in both buffet lines. Results (Table 2):

  • •Left buffet line RR (95%CI): 3.28 (1.12-9.59)
  • •Right buffet line RR (95%CI): 2.62 (1.37-4.99))

The dark turkey meat, white turkey meat, and ham cultured Staphylococcus aureus and Bacillus cereus (Table 3 and 4). Among these three food items, the white and dark turkey meat tested positive for the presence of Staphylococcus Enterotoxin Type A (SEA) and white turkey meat also tested positive for the presence of Staphylococcus Enterotoxin Type C (SEC). The presence of Bacillus cereus Enterotoxins were not detected in the dark turkey meat, white turkey meat, or ham. The green bean food samples submitted cultured Staphylococcus aureus but did not culture Bacillus cereus. SEA was detected in green bean samples as well as the Bacillus cereus hemolytic enterotoxin (HBL), but not the Bacillus cereus non-hemolytic enterotoxin (NHE). All other food items were negative.

All foods except the turkey and ham were prepared on December 10. The turkey and ham were prepared in stages from December 7-10. Temperatures were taken of initial cooked products, but temperature and time controls, monitoring during storage, preparation, cooking, hot holding and serving were non-existent. A total of 225 pounds of turkey and 146 pounds of ham were hand-sliced with utensils on surfaces that were un-sanitized prior to use. A scabbed sore and a cut on each person that sliced the meat were observed. Gloves were stated to be used during food preparation. Subsequent to the slicing process, the sliced ham was placed in 3-3.5 inch trays and turkey in 4-5 inch trays. Both were then covered with room temperature chicken broth and covered immediately in plastic wrap. Sliced meats were transported in insulated thermal units with ice packs and then stored in a commercial grade refrigeration unit at a private home. Ham slices were heated with sterno cans on December 10 to 120°F at the event location prior to serving. Turkey slices were reheated to an unknown temperature at the commissary on December 10 at 4:30 AM and transported to the event at 8:30 AM in the insulated thermal units heated to 159°F. The commissary had a history of vermin infestations and was used by six mobile units and fifteen caterers. Refrigeration unit accessible by the caterer at Commissary A was observed to not be capable of maintaining a temperature below 41°F.


This outbreak of gastrointestinal illness was caused by Staphylococcus aureus toxins in the turkey prepared and served by Caterer A at a holiday lunch buffet at a multi-business office complex in Maitland, Florida on December 10, 2014. The presence of Staphlococcus aureus toxin in the turkey, statistically significant association of illness with consumption of turkey, and the contamination of the turkey prior to thermal abuse during cooling and cold holding subsequent to the initial roasting process and prior to the end of the holiday lunch buffet strongly supports this conclusion. Contamination with Bacillus cereus of the turkey, ham and green beans served at the holiday lunch buffet contributed to the illnesses given the presence of either the pathogen or toxin in food samples and a clinical specimen. However, the degree to which illnesses were caused by each identified pathogen could not be determined. Cross-contamination of food items before, during, or following the holiday lunch buffet cannot be ruled out, which may have led to multiple food items acting as an outbreak causative vehicle or distortion of the true relationship. Initial food contamination during the holiday lunch buffet is not biologically plausible as there was insufficient time for the proliferation of the bacterial toxins prior to the end of food service. The presence of high concentrations of two types of pathogenic bacteria in several food products prepared at Commissary A by Caterer A personnel indicates a pattern of contamination and thermal abuse of the served food items.

IOM Trivia contest rules


A chance to win prizes while spreading food safety awareness? YES!


1) An individual can win one prize each day.
2) If you win a prize, you are ineligible to win again that day.
3) If you were one of the 10 winners from last week’s giveaway, you CAN still participate in this contest and win once per day like everyone else!
4) Anyone outside the United States is ineligible to win.
There will be up to FIVE winners per day for the 5-day work week (M-F) July 15th through July 19th, 2019.
5) You must FOLLOW our Twitter account @outbreakmuseum to be eligible to win in the Twitter portion of this contest.


Each winner will receive:
One (1) Official IOM branded T-shirt*, and;
One (1) Official IOM branded Frisbee**
*Sizes include S, M, L, XL, and a few larger sizes. The size you choose (if you win) is subject to supplies while they last.
**While Frisbee supplies last

This contest will take place over 5 days (Monday through Friday next week, July 15th-19th) and be held on both Twitter as well as our newsletter mailing list.

Sign up at the bottom of this page if you are interested in the mailing list⁠ and the giveaway therein—two more days of separate prizes!

Twitter Trivia Contest Details and Rules

Next week at 6am on July 15th (Monday), 6am July 17th (Wednesday), and 6am July 19th (Friday) will tweet five questions via our Twitter account: @outbreakmuseum.

The answers to these questions will be information that can be found at our website A worthy scavenger hunt, detectives!

Find the answer to one of the questions on the website, and reply to the tweet with that answer. The first to answer each question correctly* wins one of the day’s 5 prizes!
*”Correctly” is at our discretion due to the possibly abstract nature of answers, but we will try to be as fair as possible.

Mailing List Contest Details and Rules

Next week at 6am on July 16th (Tuesday) and 6am on July 18th (Thursday) we will send a single email to everyone on our mailing list.

Note: You can sign up on the email list box at the bottom of any page on this website. Make sure to check your email after a few minutes for the confirmation link!

Each day’s email will have five questions. You must answer at least three of these questions correctly. Send your answers to as soon as you are done! The first five people each day that answers any three of the five questions correctly will win both a t-shirt and a frisbee* (*while supplies last). We will reach out via email to the winners both the days’ contests.


If you win a prize you are ineligible to win again that day. Any individual may win up to one prize each day.

We will announce winners as they qualify: all winners will be selected by 7/20; winners must send us their info by 7/24 or they forfeit their prize. We will reach out to Twitter winners via Twitter messaging. We will reach out to email list winners via your listed email address.

We will ask for a valid U.S. mailing address as well as your preferred T-shirt size (and a backup size if we run out of your first choice). You MUST provide a mailing address and preferred T-shirt sizes by July 24th or you will forfeit your prize(s).

We will ship your t-shirt and frisbee* (*while supplies last) by July 31st. Please allow some time for transit.
At this time we can only ship prizes to any US state, including Alaska and Hawaii. Anyone outside the country is ineligible to win.

The Fine Print

Prizes will be shipped out by July 31st, 2019. Sizes are limited to first come, first serve. We cannot guarantee availability of your chosen size. Frisbee prizes will be given out as supplies last. Once they are gone, they are gone!

T-shirt Giveaway Rules


This giveaway will run from July 4th to July 10th. To enter, you must:
(1) FOLLOW our Twitter account: @outbreakmuseum
(2) RETWEET the giveaway tweet
(3) REPLY and tag the Twitter account name of whomever told you about the contest. If no one referred you to the contest, no reply is necessary.

At this time we can only ship prizes to any US state, including Alaska and Hawaii. Anyone outside the country is ineligible to win.


Winners will be chosen randomly on July 11th and announced publicly. If a chosen winner mentions a referring person’s name, a t-shirt will also be given out to that person, until all 10 t-shirt prizes are given out.
If you are chosen as a winner, we will reach out to you via Twitter private message. You MUST reply by July 17th, 2019 with: Your Name, mailing address, and what size t-shirt you would prefer.


We will reach out to the chosen winners by private Twitter message for a mailing address shortly after winners are determined. To reiterate: if we do not receive your reply with a valid shipping address by July 17th, 2019 you will forfeit your t-shirt prize. Prizes will be shipped out by July 30th, 2019. Sizes are limited to first come, first serve. We cannot guarantee availability of your chosen size.

Colorado Cantaloupe Listeria

Outbreak: Colorado Cantaloupe Listeria 
Product: Jensen Farms (Colorado) “Rocky Ford” cantaloupeInvestigation Start Date: 8/29/2011
Location: Multi-stateEtiology: Listeria monocytogenes
Earliest known case onset date: 7/31/2011Latest case onset date: 10/27/2011
Confirmed Case Count: 147Positive Environmental/Food Samples: 12 / 22
Hospitalizations: 143Deaths: 33

In 2011 a multistate outbreak of Listeria monocytogenes infected 147 people, including 143 hospitalizations and 33 deaths. Illnesses were associated with Colorado cantaloupes marketed as “Rocky Ford” grown at Jensen Farms.


On August 29th, 2011, two cases of Listeria monocytogenes were reported to the Colorado Department of Public Health and Environment (CDPHE). These were in addition to a L. monocytogenes case that had been reported in mid-August, bringing the total number of cases for August to three, which was unusual. By the end of August, a total of 8 cases were reported with three distinct PFGE patterns. Initial interviews using the Centers for Disease Control and Prevention (CDC) “Listeria Initiative” questionnaire implicated cantaloupe, ice cream, coleslaw, and deli meats as potential common sources of illness. While cantaloupe had not previously been associated with L. monocytogenes outbreaks, it had been added to the questionnaire after a 2000-02 FoodNet case-control study identified an increased association between illness and cantaloupe consumption.
CDPHE notified CDC of the outbreak on September 1st. CDC provided CDPHE with data from the “Listeria Initiative” database to conduct case-case studies to compare cases from the current Colorado outbreak with previously reported sporadic listeriosis cases. Because there were multiple PFGE patterns among the outbreak cases, investigators were initially unsure whether cases represented a single or multiple outbreaks.
By September 6th, there were 12 listeriosis cases and suspected food vehicles included cantaloupe, watermelon, and ham. Later the same day, the CDC informed CDPHE that Nebraska and Texas had reported L. monocytogenes cases with PFGE patterns that were indistinguishable from the Colorado cases.

From September 4th through 7th, epidemiologists collected various food items from patients’ houses for testing and the CDPHE laboratory purchased cantaloupe from three grocery stores. Only cantaloupe with an identifying produce sticker attached were purchased, as grocery store bins of cantaloupe labeled “Colorado Grown” often contained produce from multiple Colorado growers and occasionally other states. Preliminary laboratory results demonstrated that all cantaloupe from one grocery store tested positive for L. monocytogenes. On September 9th, results from the “Listeria Initiative” case-case study indicated only cantaloupe was statistically associated with illnesses. A media release warned consumers that those at high risk for L. monocytogenes infection should avoid eating cantaloupe. CDPHE informed Colorado cantaloupe growers of their concerns and arranged farm visits.
Investigators first visited Jensen Farms on September 10th. September is the end of the cantaloupe growing season in Colorado, and Jensen Farms was the only local farm still producing cantaloupes. The investigation team noted the farm changed their handling processes earlier in the year. They replaced a chlorinated water wash with new equipment that sprayed cantaloupes with municipal water and used a series of felt rollers and brushes for cleaning and drying. At the end of this process, cantaloupes were packed in boxes and refrigerated. This new process lacked a pre-cooling step and therefore did not remove “field heat” from the produce, which allowed condensation to form on the cantaloupe once boxed and refrigerated. Additionally, the new processing equipment could not be dissembled and disinfected. Investigators hypothesized L. monocytogenes colonized the equipment and was subsequently sprayed onto all processed cantaloupe. The suboptimal storage conditions further allowed the organism to multiply.

Ultimately, five PFGE patterns were identified in patient and environmental samples. Of these, all five patterns were identified from cantaloupes obtained from patient homes, four patterns were identified from cantaloupes at retail locations, three patterns were identified from environmental swabs taken at the processing facility, and two patterns were identified from cantaloupes sampled directly from the Jensen Farm’s cooler. While the initial source of contamination was never determined, all contamination of produce occurred downstream of the processing equipment. It is possible that the equipment, which was refurbished from a potato farm, was previously contaminated. Alternatively, the cantaloupes may have been contaminated prior to processing and the pathogen was amplified by the equipment. However, testing of growing fields were negative and examination of growing methods provided no evidence of their contribution to the contamination. It is also possible that contamination entered the facility via a truck that routinely carried agricultural waste between the farm and a nearby cattle ranch. The incidence of polyclonal L. monocytogenes outbreak-related strains indicates multiple niche sites, extensive and multiple contamination sources, or repeated introductions within the processing facility.
In total, there were 147 cases (40 in Colorado) in 28 states and 33 deaths (9 in Colorado). Cases were primarily older adults and very few pregnant women, as compared to other L. monocytogenes outbreaks. Investigators hypothesized pregnant women consumed cantaloupe more quickly than older adults, thereby preventing further multiplication of L. monocytogenes in their home refrigerators.

Lessons Learned

Public health increasingly identifies fresh produce as a vehicle for foodborne illness and novel pathogen-vehicle combinations. Jensen Farms’ introduction of new processing equipment and failure to follow FDA guidance about safe melon handling likely promoted L. monocytogenes contamination and colonization. In this outbreak, rapid collection of environmental specimens, coupled with the “Listeria Initiative” that facilitated rapid case-case comparisons between outbreak-related and sporadic cases, allowed for rapid identification of a food vehicle, and prompted swift intervention measures.

Tennessee Mountain Lodge

Outbreak: Tennessee Mountain Lodge 
Product: Canned Beef in GravyInvestigation Start Date: 6/30/2010
Location: Multi-stateEtiology: Clostridium perfringens & Staphylococcus aureus
Earliest known case onset date: 6/19/2010Latest case onset date: 6/23/2010
Confirmed / Presumptive Case Count: 1/52Positive Environmental Samples: 0

A suspected outbreak of foodborne illness was reported at a lodge in the Great Smoky Mountains National Park. Set meals are served at the lodge at 6 pm and 8 am, each consisting of multiple canned/packaged items. The lodge is reached by rugged foot trails and provisions for the entire season are ordered in advance and dropped by helicopter one time in the spring. Anecdotal reports suggested that no vegetarians had become ill.

Visitors were asked to visit Park Headquarters after leaving the lodge and those that had already departed were contacted by phone. Interviews revealed uniform symptoms with a tight onset period and rapid resolution; none of the visitors interviewed in-person were able to provide a stool specimen. Among 94 identified visitors to the lodge during the event period, 53 reported becoming ill during or following their trip. Two menu items had significantly high odds ratios for both event days: beef in gravy and mashed potatoes.

A single specimen was eventually procured in coordination with another state’s Department of Health, which revealed both Staphylococcus aureus and Clostridium perfringens. The symptoms and incubation period of ill visitors were consistent with C. perfringens intoxication, and the anaerobic bacterium has often been associated with canned meat products. It was theorized that the annual provision delivery may have been the source of the C. perfringens contamination if a can’s seal dislodged during the provision drop, allowing contamination before resealing when stacked for storage.


On a Monday in June, the Tennessee Department of Health’s East Regional Office (ETRO) received a report of severe gastrointestinal symptoms at a lodge in the Great Smoky Mountains National Park (GSMNP). Consultation with the National Park Service (NPS) indicated early morning onset among 7 visitors, but no administrative or food service staff were ill.
The lodge is reached by rugged foot trails and there are very limited facilities/activities onsite. Set meals are served at 6 pm and 8 am; each consists of multiple canned/packaged items that are prepared daily. Due to the inaccessibility of the site, provisions for the entire season are ordered in advance and dropped by helicopter one time in the spring. Weekly deliveries of fresh foods for the staff are made by pack llama.
A food- or water-borne pathogen was suspected based on the symptoms reported. Environmental exposures including recreational water and animal contact were included on the interview tool, in addition to items from the dining hall menu. Most visitors had departed by the time of report and could not be intercepted; a few visitors planned to descend the following day and were asked to visit Park Headquarters.


Interviews revealed uniform symptoms with a tight onset period, consistent with a pre-formed bacterial toxin. The rapid onset appeared to rule out person-to-person transmission or a traditional food-borne enteric infection. Anecdotal reports suggested that no vegetarians had become ill. None of the visitors interviewed at GSMNP were currently symptomatic and stool specimens could not be collected. Additional interviews were conducted by telephone with registered lodge visitors for the 2-day event period and bookended dates.
Visitors on the bookended dates reported no illness. Among 94 identified visitors during the event period, 53 reported becoming ill during or following their trip to the lodge, with all reporting lower gastrointestinal symptoms. There was no significant difference in symptoms or duration by visitors’ sex or age. An epidemic curve indicated that the largest proportion developed symptoms in the early morning hours of each event day, consistent with the working hypothesis that a nightly food item was the source of intoxication.

The median incubation period was 12 hours; however, this varied significantly by date of lodging (13 vs. 10.4 hours on Event-Day 1 and Event-Day 2, respectively). The decreased incubation period and an increased attack rate among visitors on Event-Day 2 both supported the idea that those visitors might have received a greater dose of the causative agent. Duration of illness ranged widely (from a single diarrheal episode to more than 4 days), but the median duration was 15 hours.
No environmental exposures were identified and only two items had significantly high odds ratios for both event days: beef in gravy and mashed potatoes. Although almost exclusively consumed together, when odds ratios were calculated for absolute consumption of food items, the beef was clearly implicated, producing an odds ratio of 17.667 (95% CI: 1.914, 163.027).
ETRO coordinated with the NPS and other states’ departments of health to attempt timely collection of stool specimens from visitors that reported ongoing illness. A single specimen was procured, revealing both Staphylococcus aureus and Clostridium perfringens. The latter was considered the more likely causative agent; the symptoms and incubation period of ill visitors were consistent with C. perfringens intoxication, and the anaerobic bacterium has often been associated with canned meat products.

Despite a strongly implicated food item, a lab-confirmed source could not be identified. Lodge policy requires that any leftover prepared food be immediately disposed of and all food containers washed and flattened to avoid attracting bears and smaller nuisance animals. However, administrators described occasional storage of unprepared leftover foods. Upon re-interview, food service workers were able to confirm that an additional can of beef was opened on Event-Day 1 and approximately of it prepared; the remainder was stored in a sealed, refrigerated container and added to the cans of beef prepared on Event-Day 2.
The annual provision drop may have been the source of the C. perfringens contamination. Although palletized to reduce can damage, lodge administrators reported that occasionally cans would pop open on impact. It was theorized that a can’s seal may have dislodged briefly during the provision drop, allowing unnoticeable contamination with the ubiquitous bacterium before resealing when stacked for storage.
The lodge’s inaccessibility posed unique challenges for investigators, Park administrators, and the lodge concessioner. Although none of the visitors required medical intervention, the extremely large numbers of out-of-state visitors to GSMNP and nearby tourist attractions (more than 10 million annually) present a concentrated area of risk for a multi-state outbreak.

Colorado Polka Festival

Outbreak: Polka Festival C. perfringens 
Product: Catered dinner (mashed potatoes, beef brisket, gravy, rolls, and holuski)Investigation Start Date: 3/14/2011
Location: El Paso County, ColoradoEtiology: Clostridium perfringens
Earliest known case onset date: 3/11/2011Latest case onset date: 3/13/2011
Confirmed / Presumptive Case Count: 3 / 27Positive Environmental Samples: N/A

A cluster of gastrointestinal illnesses due to Clostridium perfringens intoxication occurred following a catered dinner at a Polka Festival in El Paso County, Colorado on March 11-13, 2011. The caterer for this event was unlicensed, prepared all foods in their private home, and did not document food temperatures.


On Monday, March 14, 2011, the Communicable Disease (CD) program at El Paso County Public Health (EPCPH) was contacted by a Dance Club regarding a cluster of gastrointestinal illness that occurred during a weekend Polka Festival. Approximately 120 persons participated in the festival, which began with a catered dinner and dance event starting at 4:00 pm on Friday, March 11. Initial reports indicated that 26 attendees had become ill with gastrointestinal symptoms in the early morning on March 12.


A questionnaire was developed and included questions on symptoms, illness onset, and food and other exposures. Between March 15-17, the questionnaire was administered by phone to the cohort of festival attendees who were identified from an attendee list. A supplemental questionnaire was administered to food handlers for the event and contained more detailed questions about previous illness, hand hygiene, and food handling practices. Stool specimens were collected from ill persons and sent to the Colorado Department of Public Health and Environment (CDPHE) laboratory for norovirus PCR testing, sapovirus PCR testing, bacterial toxin testing, and routine bacterial culture. No leftover food items from the event were available for testing. A case was defined as a person having diarrhea (defined as three or more loose stools in a 24-hour period) after attending the Friday night event of the Polka Festival with onset of illness March 11-13. Based on the temporal clustering of illness onset, only interviewed persons who attended the Friday night event were included in the analysis.

Ninety-two Polka Festival attendees were interviewed. Eleven attendees were excluded from analysis because they did not attend the implicated Friday night event; 81 attendees that participated in the Friday night event were included in cohort analysis. Twenty-seven persons met the case definition with a total attack rate of 33% for the dinner cohort. The ill persons ranged in age from 62-84 years old, with a median of 75 years old; 60% were male. Symptoms included diarrhea (1oo%), abdominal cramps (81%), nausea (33%), fever (7%), and blood in stool (4%). The three stool specimens collected from cases were tested at CDPHE and all three were positive for Clostridium perfringens toxin. The specimens were negative for all other testing. Food exposure analysis was done for all food items served at dinner on March 11 by the caterer, desserts sold at a bake sale, and beverages sold at a cash bar run by Dance Club volunteers.

Exposure data collected from interviews were analyzed. Mashed potatoes, beef brisket, gravy, rolls, and holuski (a noodle and cabbage dish) all had elevated relative risk scores and were statistically significant. However, food exposure analysis was complicated by the fact that most people who ate the dinner had eaten some of each food item offered by the caterer. Environmental Health (EH) staff visited the owner of the catering company on March 14, 2011. This caterer did not have an active Retail Food Establishment (RFE) license when food for this event was prepared and had prepared food in their personal home rather than in a licensed commercial kitchen. The caterer indicated that all food, with the exception of the coleslaw, was prepared in their home the day before the event. Cooling of brisket, mashed potatoes, holuski and gravy was conducted in a home-style freezer and refrigerator at the caterer’s house. The size of food storage containers and time to cool the food to appropriate temperatures were not known and there was no documentation of food temperatures. EH staff were unable to observe food preparation techniques during the visit with the caterer.

All food was transported in ice-cooled units in the caterer’s personal vehicle to the venue and temperatures were reportedly checked with a dial thermometer during transport. Transport took approximately 45 minutes. Brisket, mashed potatoes, gravy, peas, and holuski were removed from units and reheated to 160°F–180°F at the venue kitchen. Interviews with food handlers revealed discrepancies in the reported temperature to which food was re-heated. No temperature logs were kept. Food was served by food handlers employed by the caterer. Caterer stated that neither they nor their staff members were ill before or during the catering event. Environmental health staff also inspected the venue kitchen, where food was re-heated and served, on March 15, 2011. No critical violations were identified although the facility was not actively preparing food at the time of inspection. CD staff conducted interviews with nine persons who were either foodhandlers or served beverages at the dinner. No persons reported being ill with gastrointestinal symptoms during the two weeks prior to the event.


EPCPH CD and EH staff investigated a gastrointestinal outbreak at a weekend Polka Festival caused by bacterial intoxication from Clostridium perfringens. At least twenty-seven people met case definition with illness onset following a dinner and dance event on March 11. The epidemic curve was consistent with a point source as there was tight clustering of illness onset among people who ate the dinner meal on March 11. No other common exposures were identified among the Dance Club attendees other than the implicated dinner. The observed clinical illness showed a short incubation period, tight clustering of illness onset, relatively brief duration of diarrheal illness and lack of secondary cases, which are characteristic findings for C. perfringens intoxication. The environmental health investigation identified several potential risk factors with food preparation by the caterer that may have contributed to C. perfringens contamination, namely time and temperature abuse during storage, transport, and reheating of food. In this outbreak, five food items were statistically linked with illness: mashed potatoes, beef brisket, gravy, rolls, and holuski. Mashed potatoes, brisket, and gravy had the highest risk ratios. Historically, these foods have been commonly associated with outbreaks of bacterial intoxication. However, it is possible that the rolls and holuski were statistically significant because most people who ate any food from the caterer ate some of each food, making the implication of a single food item difficult.

E. coli O157:H7 Hazelnuts

Outbreak: E. coli O157:H7 Hazelnuts 
Product: HazelnutsInvestigation Start Date: 02/07/2011
Location: Multi-StateEtiology: E. coli (STEC) O157:H7
Earliest known case onset date: 12/20/2010Latest case onset date: 01/28/2011
Confirmed / Presumptive Case Count: 8 / 0Positive Samples (Food): 22

Eight outbreak cases of lab-confirmed E. coli O157:H7 were identified in Michigan, Minnesota, and Wisconsin. Initial, hypothesis generating interviews identified in-shell mixed nuts as a common exposure, specifically in-shell hazelnuts. A traceback investigation confirmed that the in-shell hazelnuts consumed by cases came from a common distributor which resulted in a press release and recall. Ultimately, the close collaboration between public health and agriculture agencies in multiple states, Centers for Disease Control and Prevention (CDC), and the United States Food and Drug Administration (FDA) allowed the identification of a novel vehicle for an O157 outbreak, with a very small number of detected cases.


A multi-state outbreak of E. coli O157:H7 infections associated with hazelnuts.


On February 7, 2011, the Minnesota Department of Health (MDH) Public Health Laboratory (PHL) determined that two human clinical E. coli O157:H7 isolates submitted through routine surveillance had indistinguishable PFGE patterns. A review of the national PulseNet database revealed four additional human E. coli O157:H7 isolates with the outbreak PFGE pattern in two states (three in Wisconsin and one in Michigan). A multi-state investigation was initiated.


Eight cases from three states were ultimately identified in this outbreak Minnesota (3), Wisconsin (4), and Michigan (1). All three Minnesota cases were male and had a median age of 62 years (range, 55 to 64 years). All three cases reported experiencing bloody diarrhea and cramps, two (66%) reported fever, one (33%) reported vomiting, and none reported fever. Two cases were hospitalized, each for 3 days. No cases developed hemolytic uremic syndrome and none died.
Upon initial interview, the first two Minnesota cases both reported consuming ground beef, sausage, lettuce, and nuts during the week prior to illness onset. Specific exposure information (i.e., brand and purchase location) collected on the ground beef, sausage, and lettuce consumed by the cases indicated these items were not from a common source. Upon re-interviews, all eight cases in the three states reported consuming in-shell hazelnuts also called filberts. Four case reported consuming hazelnuts as part of mixed nuts, and seven case reported purchased hazelnuts from bulk bins at grocery stores. One Wisconsin case reported purchasing packaged in-shell hazelnuts. However, further investigation at the grocery store where this product was purchased revealed that these hazelnuts were re-packaged at the store after originally being sold from a bulk bin.
A traceback investigation conducted by the Minnesota Department of Agriculture (MDA), in conjunction with the Michigan Department of Agriculture, California Food Emergency Response Team (CAL-FERT), and Wisconsin Department of Agriculture, Trade and Consumer Protection (WDATCP) found that the mixed nuts and in-shell hazelnuts purchased by cases originated from a single distributor, DeFranco and Son’s of California. On March 4, DeFranco and Sons issued a voluntary recall of all hazelnuts and mixed nut products distributed from November 2 through December 22, 2010. Recalled product was distributed to stores in seven states (Minnesota, Iowa, Michigan, Montana, North Dakota, South Dakota, and Wisconsin). A press release was issued on March 4, 2011 to inform the public.
In-shell hazelnuts collected by MDA from a case patient’s home tested positive for the outbreak PFGE subtype of E. coli O157:H7 on March 3, 2011. Additional mixed nut samples that included hazelnuts collected from recalled retail product by WDATCP and collected from DeFranco and Son’s by CAL-FERT also tested positive for the outbreak PFGE subtype of E. coli O157:H7. DeFranco and Son’s received hazelnuts from two companies in Oregon but did not maintain internal product traceability. The FDA conducted inspections of the two Oregon companies.


This was a multi-state outbreak of E. coli O157:H7 infections associated with eating in-shell hazelnuts grown in Oregon. Rapid collaboration between multiple state health departments and state departments of agriculture were crucial in identifying in-shell hazelnuts as the vehicle. This is the first documented outbreak of E. coli O157:H7 infections associated with nuts.

Hip-hop Measles

Outbreak: Hip-hop Measles 
Product: N/AInvestigation Start Date: 5/27/2007
Location: Lane County, OregonEtiology: Measles
Earliest known case onset date: 5/20/2007Latest case onset date: 6/5/2007
Confirmed / Presumptive Case Count: 2 / 1Positive Environmental Samples: N/A
Hospitalizations: 2Deaths: 0

In 2007, two cases of measles detected in Oregon (both unvaccinated) led to an investigation of potential exposures within a hospital and the community at large. This investigation cost approximately $170,000 across local and state health departments, and the related medical system, highlighting the costs associated with measles contact investigation.



On May 27, 2007, Lane County Health and Human Services (LCHHS) received a report of a possible measles case admitted to a local hospital. The index case was in his twenties, unimmunized, and had been in Japan during his putative incubation period. A second case was identified later. The cases lived in a mid-sized urban community (pop. 200,000), and, as we were later to find out, had active social lives.


Hospital staff reviewed their employees’ immunization status and the airflow system. Measles cases and their exposed contacts were interviewed using Oregon’s standard measles case-report form. For those contacts lacking documentation of immunity, vaccine or immunoglobulin (IG) was offered. Instructions for voluntary quarantine were given to exposed non-immune contacts. The costs of containing the two measles cases was estimated for the hospital and local and state public health departments.
Public health recommendations included three tiers of contact investigation:
(1) Health-care workers (HCWs) in direct contact; patients in the waiting room and emergency department (ED); household contacts and close friends.
(2) HCWs in units potentially exposed via air flow.
(3) High-risk patients (pregnant moms, babies, immunocompromised) potentially exposed via air flow.


On May 31, 2007, Lane County officials confirmed the diagnosis of measles in the index case by polymerase chain reaction testing. His prodrome began on May 20. He flew on May 21 from Tokyo to San Francisco, and thence on May 22 to Eugene. His rash was first noted on May 25. He spent time at a local hospital ED and visited a health food store, naturopath and Japanese restaurant during his communicable period.
The patient was not given a mask while in the ED waiting for his initial evaluation; rather, he was placed in a regular airflow room and then wheeled through the hospital without a mask and ultimately put in a taxi for the ride home. Review of the hospital’s airflow system revealed that air from the ER (where case was housed but not isolated) was shared with the Coronary Care unit and Mother Baby Unit. The circulated air had a mixture of about 20% outside air and 80% recycled indoor air with 90%–95 % effective filtration and no HEPA filter.
During the investigation, the index patient refused to identify household contacts and did not respond to LCHHS phone calls, making contact investigation difficult. An unannounced home visit helped to clarify the situation and obtain new information.

Information regarding 4 persons exposed on airline flights was not received until two weeks after the likely exposure. A week later, health officials were informed of two additional persons considered exposed, having sat next to or in front of the case, but phone numbers were not provided, and they had common last names. It also transpired that the case provided an incorrect seat number, and the model of the one of the airplanes was different from that listed on the airline’s website, further confusing attempts to identify exposed persons.
A second, unimmunized case, who had socialized with the index patient the night he arrived home from Japan, developed a febrile prodrome on May 30 and a rash consistent with measles on June 1. Koplik spots were visible. He declined lab testing.
Although nurses advised case #2 to stay home to avoid spreading the disease, he went to public places. On May 29, the case caught a hip-hop show at a local concert hall, then to a downtown bar. The next night, he went out for sushi.
Three bands that played at the concert were on a national tour. During these shows, the attendees typically stand, dance and mingle, the band is on a stage just above the floor and the band members often venture into the audience. The band members were in Utah when they were notified about their possible exposure, and specimens to verify immunity were collected in Colorado. The testing was performed at CDC in Georgia, and after the tests proved negative they were vaccinated while performing in Iowa.


This investigation presented numerous challenges. Both measles patients came from families that did not believe in measles vaccination, and who “don’t think measles are a big deal.” Local public health officials’ recommendations for isolation and quarantine didn’t impede their pursuit of an active social life—which greatly increased the work of contact tracing. The following factors also complicated the response:

  1. 1. Exposures during multiple airplane flights
  2. 2. Delay in receipt of information about people exposed during travel
  3. 3. Exposures among a community of unimmunized peers
  4. 4. Delayed isolation of the case at the hospital
  5. 5. Shared ventilation between the case’s room and other hospital units
  6. 6. Lack of airborne precautions during transit through hospital at time of discharge
  7. 7. Withholding of information and non-compliance with voluntary home isolation
  8. 8. Limited documentation of measles immunity among healthcare workers

Impact of Two Measles Cases

As a result, the investigation of these two measles cases and containment of the outbreak entailed substantial amounts of personnel time and money, as detailed below:

  1. • Hospital:
  2.   – Incident Command System (ICS) activated
  3.   – 1600 titers in a 2-week period
  4.   – 97% of HCWs were immune
  5.   – Cost of titers $40,000
  6.   – 600 fit tested for N95 masks
  7.   – 10 HCWs placed on furlough for several days
  8.   – 3 HCWs furloughed for 21 days
  9.   – 63 shots given
  10.   – New policy requiring proof of measles immunity
  11.   – Infection education module updated
  12.   – Isolation & transferring process reviewed
  13.   – $100,000 (estimated cost)
  14. • Local Health Department:
  15.   – ICS activated
  16.   – 2 cases
  17.   – 168 contacts investigated
  18.   – 90% were immune
  19.   – 4 shots given
  20.   – 4 people were placed in voluntary quarantine
  21.   – $50,000 (estimated cost)
  22. • State Health Department:
  23.   – ICS activated
  24.   – $20,000 (estimated cost)

Conclusion and Highlights

This outbreak was successfully controlled, despite the potential for spread. The limited extent of this outbreak, even in the setting of broad exposure, highlights the high level of population immunity achieved in Oregon and in other states.
This outbreak and its burden on clinical and public health resources could have been limited by adherence to recommendations of the Advisory Committee on Immunization Practices (ACIP) for vaccination of high-risk adults against measles.

  1. • Consider using quarantine orders and the quarantine process as outlined in statute to minimize the risk of spreading the virus
  2. • Consider taking legal action when cases are do not comply with public health investigation and control efforts
  3. • Develop educational materials with clear, relevant messages targeting vaccine-hesitant communities affected by the outbreak
  4. • Continue efforts to ensure networking with the alternative medical community
  5. • Expand use of digital communications for public information
  6. • Ensure airborne infection control precautions in healthcare settings
  7. • Promote measles vaccination and documented evidence of immunity among healthcare workers in Oregon

Museum Exhibit Contest


Welcome, citizen, to the Museum’s first outbreak submission contest!

Submit a significant or interesting outbreak investigation and you may win official International Outbreak Museum T-shirts! The winning outbreak investigation submission will also become an official online exhibit right here on the Museum website.

   To download these rules as a PDF, Click Here
   To download these rules as a Microsoft Office Word Document, Click Here

Promotion Period:The International Outbreak Museum (IOM) Outbreak Submission T-shirt Contest begins March 1st, 2018 and ends March 31st, 2018. A winner will be chosen within 30 days of the promotion end date. We will contact the winner if additional online exhibit materials are needed.

Prize: The winner (or each member of the winning team) will receive a T-shirt in (choose one) small, medium, large, or extra large (subject to availability). In addition, your winning outbreak investigation will become an official IOM website online exhibit.

Special Requirements: Since the chosen winner’s exhibit will become an official online exhibit at, the aforementioned must be willing to work in a limited fashion with museum staff to finalize the online outbreak exhibit. This may include a request for additional information or materials (such as pictures, video, an epi curve, outbreak questionnaire, etc).

Eligibility: Anyone can submit an outbreak investigation. There are no restrictions for eligibility based upon geographic location or whether or not you participated in the submitted outbreak investigation. T-shirts will be shipped to the winners within 2-8 weeks (to the best of our ability).

How To Enter: You may enter this contest as an individual or a small team. To enter the contest, a historically significant outbreak investigation report must be submitted to International Outbreak Museum staff.

To submit your exhibit, please fill out the online exhibit submission form (below) and submit it along with any supporting materials (images, captions for images, publications, presentations, epi curve, etc) to the following email address:


NOTE: For examples of current online outbreak exhibits, please click “Outbreak Exhibits” at the top of this page or click here.

   To download this form as a PDF, Click Here
   To download this form as a Microsoft Office Word Document, Click Here


  • 1) Investigation jurisdiction (local Health Department, state Health Department, Federal, Other)
  • 2) Pathogen
  • 3) Vehicle/venue
  • 4) Case counts (confirmed/presumptive/suspect)
  • 5) Geographic distribution of cases (single county/state-wide/multi-state/International)
  • 6) First and last onset dates
  • 7) Pictures! (please include captions for each photo submitted as part of exhibit)
  • 8) Number of positive non-human specimens (water, environment, food, etc.)


  • 9) Publication citation (optional)
  • 10) Presentations (optional)
  • 11) Investigation tools (e.g., questionnaire) (optional)


Please limit the 3 sections below to a total of ~1000 words

  1. 1) Abstract: Background, Methods, Results, Conclusions
  2. 2) Highlights: unique features or reasons why the outbreak is important
  3. 3) Lessons learned
  4. Please send this completed form to