Between October and December 2020, the Minnesota Department of Health (MDH) received three complaints of illness among individuals who had eaten at the same chain restaurant in Edina, Minnesota. The City of Edina Environmental Health and the Minnesota Department of Agriculture (MDA) were notified. A more extensive investigation was conducted after the third complaint.

Electronic surveys were sent to 425 patrons identified through credit card receipts. A total of 5 cases were identified. Meal dates were October 19, November 4, November 6, December 7 and December 13. Symptoms included red/flushed faces, rash or hives and diarrhea and stomach cramps beginning between 30 and 120 minutes after the meal. All five cases consumed sushi rolls made with spicy tuna.

Spicy tuna served in the restaurant was prepared from a frozen, vacuum-packed ground tuna product received from the distributor several times per week. The restaurant reported that tuna was only thawed in the walk-in cooler or under cold running water. Pans of prepared tuna were kept 3 to 4 days.

MDA tested an unopened sample of tuna from the restaurant's supplier. Tests showed the sample contained 475 ppm histamine. A sample of the same tuna that had been prepared in the restaurant (thawed, and several ingredients added) had 3,980 ppm histamine. According to the FDA, "the presence of 50 ppm (5 mg/100 g) or more histamine is indicative of decomposition" in tuna fish and levels above 50 ppm are considered adulterated and unacceptable.

The tuna was sourced from Vietnam. No temperature storage or handling levels were identified at the restaurant or the distributor. The distributor and upstream supplier issued a recall. Investigators concluded that the source of adulteration was most likely at the supplier/manufacturer level.