Health officials do not know exactly where the outbreak originated, but they believe it may have originated with a local food vendor present at the event.
According to the DCHD, the vendors have been cooperating with the investigation.
People who attended the event are discouraged from consuming any leftover food they may have from the event and are asked to turn it over to the local health department.
A survey was sent out to people who attended the event, asking them to report what they had consumed at the event.
At least six of the people who became ill have been hospitalized.
Visitors from eight different states and six Montana counties have become ill, according to the DCHD.
New cases are still being reported and additional laboratory results are pending.
On a Facebook page created for the event, a Nevada woman who attended reported that her mother had been hospitalized for several days due to the illness.
The DCHD spokeswoman did not immediately return calls for comment Tuesday on the status of the investigation.
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