Cheese sold at a popular Kensington Market cheese shop has tested positive for listeria bacteria, Toronto Public Health reported Tuesday.

Public health officials arrived at Cheese Magic, located Baldwin Street in the heart of the market, shortly after lunch Tuesday and began throwing out several cheese products.

"We are asking people to check their refrigerator for cheese purchased prior to Sept. 3 at Cheese Magic and dispose of it," says Dr. Barbara Yaffe, an Associate Medical Officer of Health for the city's public health agency.

The investigation at Cheese Magic began after a pregnant woman developed listeriosis after eating cheese purchased at the store.

City inspectors found that cheese had been stored at incorrect temperatures and shut down the store while its owners resolved the sanitation issues.

Toronto Public Health and the Canadian Food Inspection Agency are continuing their investigation into the source of the contamination.

When ingested, listeria bacteria causes listeriosis, a potentially fatal food-borne illness.

More than a dozen people recently died from a listeriosis outbreak linked to meat produced by Maple Leaf Foods at its North York plant. Fresh Obsessions brand sliced mushrooms were also recently recalled due to listeria contamination.

"Keep in mind that the risk from listeriosis is low for healthy individuals," says Yaffe. "Those most at risk of developing serious illnesses are pregnant women, the elderly and those with weak immune systems."

Symptoms of listeriosis include vomiting, nausea, cramps, diarrhea, severe headache, constipation and fever. Symptoms usually occur within three weeks of eating contaminated foods.

There have been 14 deaths related to listeriosis, and 38 confirmed cases of the disease in Canada.