Dr. Lisa Berger said Epic Burger and Waffles — known for its headline-making cronut burger — will voluntarily remain closed as a precaution while health officials continue their investigation.
"All the food that was available at that food premise has been disposed of," Berger said at a news conference.
"Samples of that food have been sent to the public health laboratory for sampling," she said, adding that it will take a few days to get the results.
Berger said a three-hour inspection of the cronut burger maker was conducted Wednesday after people reported vomiting, diarrhoea and stomach cramps on Tuesday night.
Paramedics treated 12 people who had symptoms of gastrointestinal illnesses — five of them were taken to hospital.
EMS officials haven't been able to say if those treated had eaten food from the same vendors.
"To date, Toronto Public Health has received reports of 34 cases of persons who have reported symptoms of foodborne illness in relation to eating at the CNE," Berger said.
Health officials are asking anyone who suffered a foodborne illness at the CNE between to contact them, and noted that those who have reported illness ate at CNE between Aug. 16 and 20.
Berger also said that there are a number of ways people become ill at the fair such as "the hot weather we've had lately, dehydration, heat, food."
Prior to the exhibition, more than 1,600 food handlers had been trained, she said, adding that on opening weekend, Toronto Public Health conducted more than 200 on-site food inspections.
She said the current investigation will look at all aspects of food handling and safety.
"We're just in the very initial stages and we'll go where the facts lead us," she said.
Berger added that the number of people reporting illness "merits a complete investigation."
Chris Botshka, who attended the exhibition Wednesday with his daughter, said he doesn't think the reports of a potential foodborne illness have caused too much concern.
"Everybody is buying and eating," he said.
Botshka added that he doesn't understand the draw of the cronut burger, which combines a doughnut and croissant into a burger that is topped with maple bacon jam.
"It's not something that appeals to me so it didn't really bother me," he said.
Toronto native Brooks Nesbitt said he arrived at the exhibition expecting to try the cronut burger.
"I heard on the radio that it was here, and I heard that it was very interesting and that it was the next new big thing," he said. "I decided I'd come give it a shot as well and now I can't."
Toronto Public Health said it has yet to confirm the source of the reported illness.
CNE's general manager David Bednar said the operator of Epic Burger and Waffles has other locations at the exhibition.
"We're talking about a reputable operator," he said at the news conference, adding that whether it's eating speciality or ordinary food, "none of this food should make you sick."
"That's my concern," he said. "Whatever we need to do to make sure this doesn't happen again, we're going to do that."
Bednar said he hopes the reported illness won't prevent other people from enjoying the fair.
"I would like to think that people have enough confidence in us to know we've reacted appropriately to this," he said.
The CNE runs until Sept. 2 and features quirky food options such as Nutella fries and a bacon and peanut butter milkshake.