An outbreak of gastrointestinal illness occurred among members of a high school athletic team and their families following a team dinner held on March 3, 2015. A retrospective cohort study was conducted among those who either attended the dinner or ate leftovers from the meal.

Twenty two people met the case definition for an outbreak associated case. Ill individuals ranged in age from 14 to 54 years. Diarrhea and abdominal pain were experienced by all individuals reporting illness. The incubation period ranged from 6 hours to 12 hours. No one was hospitalized and no one died. No clinical specimens were collected for testing.

Relative risk was calculated for each item served at the team dinner to determine statistical
association with illness. Attendees who reported consuming either the taco shells or the taco
meat were almost 4 times more likely to have become ill than those who did not report
consuming these items (Relative Risk = 3.82, p-value < 0.001, 95% Confidence Interval = 0.70 –
20.90). Taco shells, the taco meat, cheese, and lettuce were the only items served that were
significantly associated with illness (p<0.05).

Samples from the catered dinner, including cheese enchiladas, taco meat, salsa, and the rice,
were tested by for Clostridium perfringens and Bacillus cereus. Clostridium perfringens was not detected, and Bacillus cereus was found in the cheese enchilada and the salsa at low levels.

Investigators discussed possible sources of contamination with the caterer who was unlicensed. All menu items except for the rice, chips, taco meat, and taco shells were prepared on Monday, the day before the event took place. All hot foods prepared Tuesday morning were subsequently placed in the refrigerator until the team dinner coordinators picked up the food at 4:00 that afternoon. After the food was delivered to the team dinner, the taco meat and the rice were placed in the oven to heat up. When the coordinator felt the meat was not heating up quickly enough, the meat was microwaved on a separate platter then returned to the oven pan before guests arrived.