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campylobacter jejuni

chicken Liver Campylobacter

Outbreak: Chicken Liver Campylobacter
Product: Chicken Livers
Investigation Start Date: 1/10/2014
Location: Multi-state
Etiology: Campylobacter jejuni
Earliest known case onset date: 12/5/2013
Latest case onset date: 12/24/2013
Confirmed / Presumptive Case Counts: 4 / 2
Positive Samples (Food): 5
Outbreak Summary:
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.
Details:
Background
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.

Methods
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.

Results
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 study2 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.

References
1. CDC. Multistate outbreak of Campylobacter jejuni infections associated with undercooked chicken livers--northeastern United States, 2012. MMWR 2013;62:874-6.
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.
Staphylococcus aureus

Holiday lunch buffet

Outbreak: Holiday Lunch Buffet
Product: Sliced Turkey Meat
Investigation Start Date: 12/10/2014
Location: Maitland, Florida
Etiology: Staphylococcus aureus & Bacillus cereus
Earliest known case onset date: 12/10/2014
Latest case onset date: 12/11/2014
Confirmed / Presumptive Case Counts: 6 / 135
Positive Samples (Food): 7
Hospitalizations: 8
Deaths: 0
Outbreak Summary:
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.
Details:
Background
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).

Methods
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.

Results
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.

Conclusions
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.
e-coli-o157

Angus Beef Patties EColi

Outbreak: Angus Beef Patties
Product: Beef Patties
Investigation Start Date: 09/17/2007
Location: Multi-state
Etiology: E. coli O157:H7
Earliest known case onset date: 08/01/2007
Latest case onset date: 10/08/2007
Confirmed / Presumptive Case Counts: 47 / 0
Positive Samples (Food): 17
Outbreak Summary:
Minnesota Department of Health (MDH) staff quickly identified the outbreak vehicle when the first four detected outbreak cases all reported consuming the same brand of premade beef patties. Investigators tracked down detailed product information from two cases, and two leftover boxes of beef patties obtained from case households were found to be produced on the same day and same production line in the same factor, literally produced within one minute of each other. Because of this link, MDH and the Minnesota Department of Agriculture issued a health alert and press release that day to notify the public of these findings before food testing results were available. Eleven outbreak cases were identified in Minnesota, including four cases of hemolytic uremic syndrome (HUS), a life-threatening illness. This high percentage of HUS among cases of E. coli O157 infection suggests a particularly virulent strain of Shiga-toxigenic E. coli (STEC) or that cases ingested a heavy dose of bacteria.

Thirty-six additional cases of E. coli O157 infection were identified from fourteen other states, as their bacterial specimen isolates yielded indistinguishable pulsed-field gel electrophoresis (PFGE). The outbreak PFGE strain of E. coli O157 was ultimately cultured from raw beef patties from all six boxes of product recovered from Minnesota outbreak case homes and tested by the Minnesota Department of Agriculture. This product appeared to be heavily contaminated – 13 of 13 subsamples taken from each box were positive. The outbreak strain of E. coli O157 was also isolated from implicated leftover food product collected from case homes in California, South Carolina, Tennessee, and Wisconsin. The rapid epidemiologic investigation (and the decision not to wait for food testing results or an unnecessary analytic study) undoubtedly prevented many additional cases, and may have prevented consumers from dying after consuming this product.
Details:
Background
On September 17, 2007, the Minnesota Department of Health (MDH) was notified of a patient who presented to an emergency department with bloody diarrhea and was subsequently diagnosed with HUS. The patient had attended a large gathering and no other illnesses were reported from individuals who attended this event. On October 3, 2007, MSPHL identified two additional E. coli O157 isolates through routine surveillance with PFGE patterns that were indistinguishable the first case patient isolate. The first of these two new isolates was from the sibling of the first case and was considered to be a secondary infection (likely transmitted from one sick person to another). The second of these two new isolates came from a third patient who was unrelated to the previous two cases; this launched a local, and ultimately national, outbreak investigation.

Methods
Minnesota E. coli O157 cases were identified through routine surveillance of laboratory-confirmed cases of Shiga-toxigenic E. coli (such as E. coli O157:H7), active hemolytic uremic syndrome (HUS) surveillance, and foodborne illness complaint calls from the public. Phone interviews were conducted with all cases to collect information regarding symptom history and food exposures. Cases were asked to state where they shopped for groceries, and customer identification numbers were collected from consenting cases to obtain or verify food brand and purchase date information.

When available, leftover ground beef patties or packaging were collected from case households. Information that was provided from packaging included product name, unit size, the United States Department of Agriculture (USDA) establishment number, the best-if-used-by (BIUB) date, the production line number, and the production time. The Minnesota Department of Agriculture (MDA) Laboratory tested each product submitted for the presence of E. coli O157 by polymerase chain reaction (PCR) and culture. If E. coli O157 was isolated, isolates were submitted to the MDH PHL for PFGE testing.

Results
A routine surveillance interview revealed that the first case had consumed a beef at a large gathering, three days prior to illness onset. The case reported that the beef was not fully cooked, having noticed that the middle of the patty was still pink. The source beef patties were premade and had been purchased at a local Sam’s Club store. No leftover product was available for testing, and the packaging had been discarded.

The third identified case of E. coli O157 infection reported consumption of premade beef patties purchased from a Sam’s Club store. On October 4, 2007, MDH collected American Chef’s Selection Angus Beef Patties and packaging materials from the third case household and submitted the product to the MDA Laboratory for testing. Fortunately, production details which were printed on the bottom of the beef patty package; this helped regulators to understand more about when and where the beef patties were produced.

Later that same day, MDH epidemiologists were notified of a fourth E. coli O157 case isolate with an indistinguishable PFGE pattern. This case was interviewed immediately and also reported consumption of the American Chef’s Selection Angus Beef Patties from Sam’s Club; investigators collected information from the beef patty packaging materials. The beef patties that the third and fourth case consumed were produced in the same facility on the same production line (L5) within one minute of each other (11:58 and 11:59). Because of this link, MDH and MDA issued a health alert and press release that day to notify the public of these findings. A recall of approximately 850,000 pounds of ground beef closely followed these alerts, announced by the United Stated Department of Agriculture Food Safety and Inspection Service (USDA-FSIS) on October 6, 2007.

Outbreak case identification continued after the press release had been issued. In total, eleven E. coli O157 cases were identified in Minnesota during the investigation. The median age was 19 years (range, 1 to 85 years) and seven (63%) cases were male. Onset dates ranged from September 10 to October 8, 2007. All cases had diarrhea, 10 (90%) had bloody diarrhea, seven (63%) were hospitalized, seven (63%) had abdominal pain or cramping, seven (63%) had fever, six (54%) had vomiting, and four (36%) developed HUS. The median duration of hospitalization for cases without HUS was 4 days (range, 3 to 4 days). For cases with HUS, the median duration of hospitalization was 21.5 days (range, 8 to > 60 days).

All eleven E. coli O157 cases with isolates of the outbreak PFGE strain reported to the MDH during the investigation had consumed American Chef’s Selection Angus Beef Patties from Sam’s Club in the 7 days prior to illness onset. Of these, ten cases consumed the product grilled in patty form, and one case reported consuming the product slow-cooked in chili. The products were purchased from four different Sam’s Club locations, three of which were in the Minneapolis-St. Paul metropolitan area.

The implicated ground beef patties were packaged in boxes containing eighteen frozen, premade patties that each weighed 1/3 of a pound, for a total net weight of six pounds. Leftover product was collected from four other cases, for a total of six Minnesota case households. Of these six households, three had original beef patty packaging material available. Packaging material revealed that the three beef patty products were produced on the same day; all three had a BIUB date of 2/12/08. As discussed above, two of these products were produced on the same line (L5) within one minute of each other (11:58 and 11:59). The third product was produced on a different line (L6), but had a similar time stamp (11:57).

All beef patty product samples collected from Minnesota case households were positive for the outbreak PFGE subtype of E. coli O157. No additional PFGE subtypes were isolated from the six product samples submitted from case households. Second enzyme PFGE testing revealed that all human and ground beef isolates were indistinguishable by the second enzyme as well. The outbreak subtype of E. coli O157 was also cultured from implicated ground beef by public health laboratories in California, South Carolina, Tennessee, and Wisconsin.

There were 36 additional E. coli O157 isolates reported from 14 other states that had PFGE patterns indistinguishable from the outbreak subtype pattern. Onset dates for all patients nationwide ranged from August 1 to October 8, 2007. Two additional HUS cases were identified, both from Tennessee. Ten of the 20 (50%) cases from states other than Minnesota that reported consuming ground beef in the week prior to becoming ill specifically reported consuming the implicated product.


Conclusions
This was a multi-state outbreak of E. coli O157:H7 infections associated with the consumption of premade, frozen ground beef patties purchased from Sam’s Club outlets. Eleven cases were identified in Minnesota, including four cases of HUS. The investigation resulted in a recall of approximately 850,000 pounds of ground beef. Routine PFGE subtyping of E. coli O157 isolates combined with routine interviewing of cases, including detailed questions about consumption of ground beef (i.e., brand and purchase locations), enabled identification of the outbreak vehicle with a small number of cases. The type and brand of product was so specific that an analytic study was unnecessary, and interventions were implemented prior to laboratory confirmation of E. coli O157 in the food product.
clostridium

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, Colorado
Etiology: Clostridium perfringens
Earliest known case onset date: 3/11/2011
Latest case onset date: 3/13/2011
Confirmed / Presumptive Case Counts: 3 / 27
Positive Samples (Environmental): N/A
Outbreak Summary:
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.
Details:
Background
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.

Methods/Results
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.

Conclusions
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.

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clostridium

Tennessee Mountain Lodge

Outbreak: TENNESSEE MOUNTAIN LODGE
Product: Canned Beef in Gravy
Investigation Start Date: 6/30/2010
Location: Multi-State
Etiology: Clostridium perfringens & Staphylococcus aureus
Earliest known case onset date: 6/19/2010
Latest case onset date: 6/23/2010
Confirmed / Presumptive Case Counts: 1 / 52
Positive Samples (Environmental): 0
Outbreak Summary:
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.
Details:
Background
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.

Results
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.

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E. coli O157:H7

E. Coli O157:H7 Hazelnuts

Outbreak: E. COLI O157:H7 HAZELNUTS
Product: Hazelnuts
Investigation Start Date: 02/07/2011
Location: Multi-State
Etiology: E. coli (STEC) O157:H7
Earliest known case onset date: 12/20/2010
Latest case onset date: 01/28/2011
Confirmed / Presumptive Case Counts: 8 / 0
Positive Samples (Food): 22
Outbreak Summary:
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.
Details:
A multi-state outbreak of E. coli O157:H7 infections associated with hazelnuts.

Background
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.

Results
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.

Conclusions
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.

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listeria

Listeria Soft Cheese

Outbreak: Listeria Soft Cheese
Product: Soft Cheese
Investigation Start Date: 06/27/2013
Location: Multi-State
Etiology: Listeria monocytogenes
Earliest known case onset date: 5/14/2013
Latest case onset date: 6/16/2013
Confirmed / Presumptive Case Counts: 5 / 0
Positive Samples (food / Environmental): 18 / 1
Outbreak Summary:
Five outbreak cases of listeriosis were identified in Minnesota, Indiana, Illinois, and Ohio. The use of the CDC Listeria Initiative questionnaire to identify a soft cheese signal, along with re-interviewing cases (or their proxies) and calling restaurants to get specific details on cheese brand and cheese type were critical in identifying the outbreak vehicle. Environmental isolates in the PulseNet national database that were collected from the Crave Brothers cheese production plant (and indistinguishable from outbreak case isolates) were also a key supporting clue. These clues led to the testing of Crave Brothers cheese samples and detection of the outbreak stain in this product.

This investigation resulted in perhaps the fastest identification of a commercially distributed food vehicle of a listeriosis outbreak; the cluster was detected in Minnesota on June 27 and public health interventions were implemented on July 3 (6 days later). This was a remarkable accomplishment, especially with only 5 cases to work with. The rapidity of the investigation can be attributed primarily to the urgency displayed by the lead investigator and the aggressive acquisition of details on brand and type of soft cheese consumed, in collaboration with epidemiologists in the other affected states.

The MN CoE has created a detailed case study about this investigation that can be used for training public health practitioners in outbreak investigation. Public Health students love it too!
Details:
A multi-state outbreak of listerosis associated with soft cheese from Crave Brothers.

Background
On June 27, 2013, the Minnesota Department of Health (MDH) Public Health Laboratory (PHL) determined that two clinical Listeria monocytogenes (LM) isolates submitted through routine surveillance had indistinguishable PFGE patterns. A review of the national PulseNet database revealed three additional LM isolates with the outbreak PFGE pattern in Indiana, Illinois, and Ohio. A multi-state investigation was initiated.

Results
Five cases from three states were ultimately identified in this outbreak (Minnesota, 2; Indiana, 1; Illinois, 1; and Ohio, 1). In addition, subsequent whole genome sequencing efforts identified another likely case in Texas, but exposure information was not available. Four (80%) cases were female and the median age of the cases was 55 years (range, 31 to 67 years). All five cases were hospitalized and one died. Listeria Initiative case report forms were completed for all five cases and all five reported consuming a variety of soft cheeses. Potato salad was reported by both Minnesota cases; however, no other cases reported consuming it. Epidemiologists conducted a case-case comparison study to compare outbreak case food consumption rates against estimated background consumption rates using non-outbreak associated LM cases. LM cases with the outbreak PFGE pattern were significantly more likely than sporadic LM cases to have consumed any soft cheese (odds ratio, 16.8; 95% confidence interval, 1.2–8) and yogurt (odds ratio, 7.5; 95% confidence interval, 1.3–8). Review of the initial interviews revealed that cases reported different brands of yogurt, making this an unlikely source of illness.

The Minnesota cases were re-interviewed to get additional specific product details on the soft cheese exposures. The first Minnesota case reported consuming a cheese plate at a restaurant in North Dakota. The investigator called the restaurant which reported that the cheese plate included Crave Brothers Les Frères cheese. The Illinois case reported consuming Crave Brothers Les Frères cheese purchased from a grocery store. The Indiana case reported consuming a cheese plate at a restaurant, and a review for the restaurant menu indicated that Crave Brothers Les Frères was served on the cheese plate. The Ohio case was re-interviewed and also reported consuming a cheese plate at a restaurant which included Crave Brothers Petit Frère cheese. PulseNet identified non-human isolates in PulseNet with the outbreak PFGE pattern that had been collected from the Crave Brothers cheese production facility in 2010 and 2011.

On July 1, Crave Brothers cheese was collected for testing from two locations of the grocery chain where MN case #2 had purchased the product, and submitted to Minnesota Department of Agriculture (MDA) for LM testing. In addition, leftover blue cheese, Irish cheddar, parmesan cheese, and an unknown hard cheese were collected for testing from MN case #2’s home. By July 3, Enzyme-linked Fluorescent Assay results indicated that a wedge of Crave Brothers Petite Frère with Truffles from one grocery store location in Minnesota, two wedges of Crave Brothers Les Frères from another location of the same grocery store chain in Minnesota, and a wedge of blue cheese collected from MN Case #2’s home all tested positive for LM. A traceback of the Crave Brothers cheese consumed by the cases revealed that the cheeses had different distributors, which indicated that the source of the contamination was the Crave Brothers plant.
A press release was issued warning consumers not to eat Crave Brothers Les Frères, Petit Frère, and Petit Frère with truffles and Crave Brothers issued a voluntary nationwide recall of these cheeses.
The spouse of the second Minnesota case called investigators to report that he thought they had purchased Crave Brothers Petit Frère. He did not have a receipt but had used a credit card to make the purchase. The investigator contacted the grocery store and gave them the credit card transaction numbers, the date of the transaction, and the dollar amount of the transaction. Using this information the store was able to reprint the original receipt with included Crave Brothers Petit Frère.

Conclusions
This was a multi-state outbreak of LM infections associated with Crave Brothers cheese. The use of the Listeria initiative questionnaire along with re-interviewing cases (or their proxies) and calling restaurants to get specific details on cheese brand/type were critical in identifying the outbreak vehicle.
Environmental isolates in the PulseNet national database that were collected from the Crave Brothers cheese production plant were also a key supporting clue. This investigation resulted in perhaps the fastest identification of a commercially distributed food vehicle of a listeriosis outbreak.

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listeria

Colorado Cantaloupe Listeria

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

Outbreak Summary:
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.

Documents

Details:
Highlights
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.

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