Top 5 Takeaways

  1. Identification of Outbreak Source: Morel mushrooms were identified as the likely source of a gastrointestinal illness outbreak in Montana, emphasizing the importance of proper mushroom preparation.
  2. Case-Control Study Findings: A case-control study revealed a strong association between the consumption of raw morel mushrooms and illness, highlighting a dose-response relationship.
  3. Public Health Response: The investigation led to educational messaging about morel mushroom safety and underscores the need for thorough cooking to mitigate potential toxins.
  4. Epidemiologic and Laboratory Analysis: Despite extensive testing, the specific toxin causing the illness was not identified, pointing to gaps in knowledge about morel mushroom toxicity.
  5. Recommendations for Morel Mushroom Consumption: To reduce health risks, morel mushrooms should always be cooked thoroughly before consumption.

Original Article Author and Citation

Corresponding Author

Heather Demorest,

Suggested Citation

Demorest H, Hinnenkamp R, Cook-Shimanek M, et al. Outbreak Linked to Morel Mushroom Exposure — Montana, 2023. MMWR Morb Mortal Wkly Rep 2024;73:219–224. DOI:


This report outlines an outbreak of gastrointestinal illness in Montana, attributed to the consumption of morel mushrooms, a generally edible fungi. Following reports of 51 persons experiencing illness, with two fatalities, an investigation identified raw morel mushrooms as a strong link to the illnesses.


The investigation involved collaboration among local, state, and federal health departments, conducting a matched case-control study among restaurant patrons. This study aimed to identify the outbreak source and assess potential dose-response relationships.


The findings suggest that improper preparation of morel mushrooms, specifically consuming them raw or undercooked, likely led to the outbreak. This incident highlights the critical need for public education on safe mushroom preparation practices.


To mitigate the risk of illness from morel mushrooms, it is crucial that they are thoroughly cooked before consumption. This outbreak underscores the importance of food safety education and the need for further research on the potential toxins in morel mushrooms.

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