On July 11th, 2014, a picnic was held on a native American reservation located in Minnesota for the Elders of the Fond du Lac Band of Lake Superior Chippewa. Within a matter of days, a number of the attendees had become ill, and on July 17th, at least five of them sought emergency medical treatment at Community Memorial Hospital, in Cloquet, Minnesota. An emergency room physician suspected E. coli due to the bloody diarrhea and other symptoms of gastroenteritis, and stool tests were run. When the results of the stool tests confirmed E. coli O157:H7, the illnesses were reported to the Minnesota Department of Health (MDOH) according to hospital and state procedures.
The MDOH immediately began to look for any other cases that were related to the same outbreak, including cases were a stool culture isolated E. coli with a Pulsed-Field Gel Electrophoresis (PFGE) pattern indistinguishable from, or within 3 bands of, the main outbreak pattern by at last 1 enzyme. According to state policy and practice, all positive individuals were then interviewed about their recent eating behavior. Because the Fond du Lac Elder Picnic had been a catered event, MDOH investigators began by investigating Jim-N-Joe’s Northland Katering, a company that is situated Cloquet. Jim-N-Joe’s Northland Katering is licensed by the University of Minnesota and operates in a kitchen at the Cloquet Forestry Center. During the investigation, MDOH determined that Jim-N-Joe’s Northland Katering had catered at least seven events, a number of which had been identified as possible sources of cases of E. coli, and interviews were conducted with 199 attendees. Compete lists of attendees was not available for each event. As the interviews were conducted, 74 of the attendees reported gastrointestinal illness, including at least 57 that were within the parameters of the outbreak specifications. In addition, Jim-N-Joe’s Northland Katering food workers were also interviewed and asked to provide stool samples for testing, with at least one employee admitting to working ill while experiencing gastrointestinal illness during the outbreak period. The employee’s stool test was positive for the outbreaks train of E. coli O157:H7.
After the exhaustive investigation, MDOH identified victims who had attended five of the events catered by Jim-N-Joe’s Northland Katering between the 1st and 17th of July, 2014. At least one secondary infection was identified. And while most victims resided in Minnesota (48), four were residents of Wisconsin, two were residents of Alabama, and one was a resident of each of Illinois, Indiana and Ohio. In short, during the course of the investigation, at least 57 individuals were identified as victims of the Jim-N-Joe’s Northland Katering outbreak of E. coli O157:H7.
As the investigation narrowed to identification of the source of the E. coli, MDOH began to analyze the foods served and consumed by the victims. At least 43 of the identified victims had attended a single catered event, the Fond du Lac picnic (other events included a focus group on July 16th, a wedding on July 12th, a three-day conference from the 14th to the 16th of July, and a tribal meeting held on the 17th). In a univariate analysis of attendees at the picnic, 37 of 38 victim respondents reported having consumed potato salad, compared to only 44 of 66 in the control group (a statistically significant departure with a 95% confidence interval p<.0001). On July 21, an MDOH investigator collected leftover food from Jim-N-Joe’s Northland Katering, and the potato salad which had been served at three of the catered events tested positive for the outbreak strain of E. coli. All other food items were negative.
This analysis, coupled with analysis performed on the other events, initially implicated two ingredients in the potato salad, onions and celery. As the investigation continued, however, a number of identified victims were found to have attended events were no potato salad was served, and in some cases, at which only celery was consumed. In all cases, the celery served came from the same batch of celery as was used to make the potato salad. Given that celery was the only common food consumed by all victims and that it had all originated from the same shipment/lot, investigators began to focus on the source of the celery. The celery implicated in the outbreak had been received by Jim-N-Joe’s Northland Katering from Upper Lakes Foods, Inc. on June 25th in a case of 24 heads. Working with Pro*Act distributing and Mann Packing, MDOH traced the celery to Martignoni Ranch, block 5c, in Gonzalez, California. The California Department of Health was then able to confirm that the celery was produced on a farm owned by Costa Farms and harvested by Mann Packing. The celery was harvested from a field situated next to a now-defunct dairy operation which is occasionally occupied by grazing cattle.
Just over one-third of the victims identified had sought medical attention, with about one-in-six requiring hospitalization. No cases of Hemolytic Uremic Syndrome or death were reported. About 65% of the victims were women.