Officials are awaiting test results to determine whether seven workers at a summer camp near Amherst, N.S., became sick with listeria-tainted meat.

The workers at Camp Tidnish, a camp in New Brunswick serving Nova Scotian children with physical and mental disabilities, were quarantined and treated late last week.

Heather MacDonald, a spokeswoman for the camp, said staff members consumed a product on the recall list of foods produced by Maple Leaf Foods before it was taken off the camp's menu.

"They were exhibiting some of the symptoms," she told CBC News on Monday. "There was a strong suspicion that it came from that particular Maple Leaf [Foods] product that we had on hand."

Federal food inspectors are testing samples for evidence of the Listeria monocytogenes bacteria, which causes listeriosis.

Symptoms include vomiting, nausea and diarrhea. Public health officials say symptoms can occur up to 70 days after contaminated food is consumed, with the average incubation period of 30 days.

Health Canada said Monday that 12 deaths have been linked to a recent listeria outbreak. There are now 26 confirmed cases, up from 21. As well, the number of suspected cases is now 29, down from 30, officials said.

MacDonald said it was tough to keep Camp Tidnish going with seven staff in sick bay.

"That had left a small group of staff to effectively be operating the program, and we decided in our best interests to shut down the camp a few days early," she said.

Dr. Denis Allard, a district health officer in New Brunswick, said officials have investigated the facilities at the camp just inside the New Brunswick border.

"Our inspectors have gone and done a regular inspection that they would do when an outbreak is notified, which is looking at the food-handling practices," he said.

Allard said it could be a week before officials know whether the workers suffered from listeriosis or a similar illness.

The recall list has been expanded to include more than 200 items under brands such as Maple Leaf, Compliments, Hickory Farms and Schneider's. All of the products were manufactured in Toronto at the same Maple Leaf Foods factory.