TORONTO - A massive recall of deli meats likely has many Canadians checking their refrigerators and memories of meals past over fears they may be among those afflicted with the bacterial illness listeriosis.
An outbreak of the disease caused by Listeria monocytogenes is being investigated, and there has been a recall of contaminated meat products by Maple Leaf Foods. Officials have yet to establish a link between the outbreak and the food produced at the company's meat plant in Toronto.
So far, the infection has sickened 16 people and killed one, but some health officials believe the number of those affected will likely rise.
So what should you do if you know or think you've eaten any of the 23 products -- including ham, smoked turkey and roast beef -- pulled by the company this week from grocery store shelves?
That very much depends on whether someone has developed symptoms, how serious they are and if the person falls into certain risk groups for severe disease, says Dr. Andrew Simor, head of microbiology at Sunnybrook Health Sciences Centre in Toronto.
"In most cases, the infection is pretty mild, people might not even be aware they have it," Simor said Thursday. "They might have a mild flu-like illness, maybe some mild abdominal pain and diarrhea."
"I think if people have eaten (any of these foods) but feel perfectly well, they have nothing more to worry about and the vast, vast majority of people who have eaten these products will not get sick."
However, eating foods laced with Listeria can lead to life-threatening forms of the disease in vulnerable groups, among them the elderly, those with compromised immune systems and the unborn fetuses of pregnant women.
Listeria bacteria, which first infect the gastrointestinal tract, can invade the bloodstream, causing blood poisoning, and then travel to the brain and spinal cord, resulting in meningitis or encephalitis.
In pregnant women who are infected, the organism can proliferate in the placenta and cause fetal death or premature birth, with "severe, overwhelming infection of the newborn," Simor said.
Simor said that if a person has symptoms suggestive of listeriosis and has also developed fever, headache or a stiff neck, they should seek immediate medical attention.
"Those would be the manifestations of the severe form of the disease. ... When it happens -- and it's fortunately not common -- but when it happens it can be a very serious, life-threatening disease."
But when it comes to various kinds of bacteria, L. monocytogenes is a bit of an oddity. It has an extremely variable incubation period of two to 90 days, so tracing listeriosis back to the ingestion of a particular food can be tricky, Simor said.
"It can be as short as a few days but it can my be as long as a couple of months, complicating investigation of an outbreak because it's very difficult for people to remember what they've eaten a few weeks or a few months before," he said.
"And certainly the food they ingested weeks or months before is not likely to be around in order to do cultures to determine the source."
