Toronto public health officials have been investigating a foodborne illness outbreak among about 150 people who visited the Canadian National Exhibition there this past week. Officials reportedly collected food samples for testing and interviewed more than 100 people. They said that the only common food consumed by those who later experienced gastrointestinal symptoms was the “cronut burger” sold by EPIC Burgers at the event. A “cronut burger” is a hamburger patty topped with cheese and served between layers of a sugar-cinnamon pastry that’s a cross between a donut and a croissant. “Early laboratory test results indicate that samples of the cronut burger were contaminated by staphylococcus aureus toxic, which is a recognized cause of foodborne illness,” said Dr. David McKeown, Toronto’s medical officer of health. Symptoms of illness range from an upset stomach to more serious symptoms, including diarrhea, fever, vomiting, abdominal cramps and dehydration.