In May 2013 a sushi restaurant located in Mankato, Minnesota was implicated in an outbreak of Scombroid Fish Poisoning. A physician at an urgent care facility notified Minnesota public health investigators that a patient with hive-like rash, flushing, anxiety, tingling around the mouth and headache had been seen at 2:22 pm. A meal companion had similar symptoms. Minnesota Department of Health staff interviewed the original complainants and additional restaurant patrons identified from credit card receipts. A total of 5 customers who ate at the restaurant on May 22 were interviewed. The two original complainants were the only two who met the case definition. Both cases responded to treatment with anti-histamines; however neither had completely recovered at the time of interview. Environment health specialists determined that the restaurant received portions of frozen tuna from a distributor in Chicago. The standard protocol was to thaw the frozen packages at room temperature for approximately 1 hour, remove the tuna from the packages and individually wrap portions in plastic wrap. The tuna temperatures recorded at the time of inspection were all below 41 degrees F; however, the thawing practices observed could have resulted in temperature abuse. Minnesota Department of Agriculture collected spicy tuna sushi from a case's home and two samples from the restaurant that were from the same shipment but different packages. Both of the restaurant tuna samples had histamine levels within the normal range (<10 ppm). The level of histamine in the sushi sample collected from the case's home was 4890 ppm. Investigators concluded that histamine production occurred during food preparation at the restaurant; however, improper handling prior to the restaurant receiving the product could not be ruled out.