In July 2014 Minnesota health and agriculture agencies investigated and outbreak of E. coli O157 infections among residents of the Fond du Lac reservation. Many of the ill cases attended a variety of events taking place in mid-July. A catering company in Cloquet, MN, Jim-N-Jo's Katering, was a suspected source as the company catered the majority of events taking place around the time period of interest.

Fifteen cases of confirmed E. coli O157 were identified. Epidemiologic data implicated potato salad served at an Elder Picnic on July 11 and the outbreak strain of E. coli was isolated in a leftover sample of potato salad. However, some of the ill persons did not attend the picnic but attended other events where potato salad was not served.

In total, 57 outbreak associated cases were identified. Nine people were hospitalized. No one died.

One common food item between the Elder picnic and the wedding was celery which was in the potato salad and served on a vegetable tray at the wedding. Investigators in California and Minnesota traced the lettuce to a producer in the Salinas Valley, California. Water and soil samples were collected for E. coli testing but all were "not found" for the pathogen.