The Montana Department of Public Health and Human Services (MTDPHHS) and Gallatin City County Health Department (GCCHD), with the support of the CDC, conducted a case-control study to identify illnesses that are associated with food and to assess the dose-response relationship.

Questionnaire data were collected by state and county health department staff members using Jotform software, and those deidentified were sent for analysis to CDC, where matched and unmatched logistic regression analysis was conducted using SAS software.

The odds of consuming a special sushi roll with morel mushrooms among cases were 15.78 times higher than those of control patients and 10.77 times higher among cases for eating any morels.

The FDA has published information on morels and other mushrooms that can be cultivated.

The MTDPHHS and GCCHD gave recommendations on proper storage and preparation to reduce the illness risk.

Findings from the investigation suggested uncooked or undercooked morel mushrooms were the source of the outbreak and there was a clear association between the consumption of morels and gastrointestinal illness.