Dr. Lisa Berger, an associate medical officer with Toronto Public Health, told the CBC the department was notified Tuesday night that paramedics treated 12 at the CNE and five were recommended to be taken to the hospital.
However, Wednesday heath officials received reports of "34 cases of persons who have reported symptoms of food-borne illness in relation to eating at the CNE," Berger said.
Some of those who became ill at the CNE told officials they had eaten at Epic Burgers and Waffles and as a result, the food stand was closed as a precaution.
Berger, said Toronto Public Health did not close the premise, but the CNE ordered Epic Burgers and Waffles, the maker of the cronut burger to stay closed until a health inspection was completed.
Health officials stressed no food source has been identified.
The restaurant's CNE stand was inspected last Friday and passed, the public health's DineSafe website said.
The cronut -- layers of puff pastry made into a doughnut shape and fried -- was created by a New York City bakery and thanks to the Internet, other versions of the cronut became a international delicacy.
The Toronto version -- The Bacon Jam Cronut Burger -- added a cheeseburger and maple bacon to the half-doughnut, half-croissant bun.