In April 2010, Minnesota Department of Health (MDH) staff investigated an outbreak of gastrointestinal illnesses among employees of an insurance company. On March 31, approximately 35-40 people were served a catered meal from a restaurant at noon or 6 pm.

The menu consisted of prime rib, yellow asparagus, garlic mashed potatoes, salad, dinner rolls, and brownies.

Epidemiologists from MDH interviewed meal attendees to obtain information on food/beverage consumption and illness history. Due to the length of time that had elapsed between the cases’ illnesses and the report of the outbreak, no stool samples were collected for testing. Nineteen of 27 meal attendees who were interviewed met the case definition for an outbreak case. Consumption of garlic mashed potatoes was borderline significantly associated with illness (18 of 19 cases vs. 4 of 7 controls; odds ratio, 13.5; 95% confidence interval, 0.83 to 456; p = 0.05). No other food/beverage item or meal time was significantly associated with illness. No one was hospitalized and no one died.

A routine inspection by an MDH EHS sanitarian was conducted on the implicated meal date. The inspection found a hot-holding violation with the mashed potatoes. Illnesses were consistent with a bacterial intoxication, most likely Clostridium perfringens.