Friday, a third person was confirmed dead from a listeriosis outbreak in Ontario. The Canadian Food Inspection Agency acknowledged the fatality as the hunt for the source of the bug continues. But a fourth death - one that occurred in July - has now been linked to the bug. The Medical Offer Of Health for Hasting and Prince Edward counties, Dr. Richard Schabas, confirmed the link Friday night. That victim was an elderly man.

The case has become a difficult one to track, with several provinces and cities reporting outbreaks, but none yet officially tied to the recall of tainted meats found at the Maple Leaf Food plant in Toronto.

The third death came in St. Catharines. Another fatality involved a senior in Waterloo, whose death was revealed by health experts earlier in the day.

"We have one confirmed case of listeria that's associated with the provincial outbreak and that case is deceased," noted Chris Komorowski of Waterloo Public Health.

The first death, an elderly woman in Hamilton, was outlined on Thursday.

But knowing the third death was in the Niagara Region still doesn't solve the lingering listeria mystery.

"That person was an elderly woman over the age of 65. She died in June and in fact had the same strain of listeria that is being implicated in this outbreak," reveals CityNews Medical Specialist Dr. Karl Kabasele.

"Now the problem here is we don't know the exact cause of death. They're still awaiting word from either the coroner or some physician to find out whether the bacteria either caused the death or contributed to it."

Officials confirm 17 people have also been sickened by this same strain - 13 in Ontario, two in B.C., one in Saskatchewan and one in Quebec - and they are continuing to investigate 38 suspected cases across the country. One person in B.C., a 64-year-old man, succumbed to his sickness at a hospital Friday, Provincial Health Officer Doctor Perry Kendall has confirmed.

But whether it's tied to the meat is still uncertain, as efforts continue to trace the bug's 'fingerprint' across the nation.

Maple Leaf Foods was forced to issue a massive recall of a large number of its deli meats, sold primarily to restaurants and nursing homes, and to close down its Toronto plant after the presence of listeria was discovered there.

"Since the beginning of the [Canadian Food Inspection Agency's] investigation into the listeria outbreak, we've been working very closely with public health officials, the Public Health Agency of Canada and Health Canada to determine the potential role of food and its source in the listeria-related illnesses that were originally reported in Ontario and now elsewhere," Dr. Richard Arsenault of the CFIA explained Friday.

Meanwhile, Toronto is also dealing with the aftermath of the crisis, confirming there are several cases being probed here, as well.

Eight instances of listeriosis have been reported in the city - three of them with a confirmed link to the outbreak, four probable cases and one suspected case. Six of the eight people were or have been hospitalized.

The most recent case was reported Friday.

A 36-year-old pregnant woman has also acquired listeriosis, but officials said it's a "sporadic" case and not the same strain as the one associated with the outbreak.

The bacterial infection may have contributed to three deaths in Toronto, Dr. Venita Dubey of Toronto Public Health said, but was not the actual cause.

"They all had chronic underlying medical conditions, such as coronary artery disease, so they died of something like a heart attack, but they happened to also have listeria, so it may have contributed to the death but it did not cause the death," she explained.

For more on Toronto Public Health's response to this outbreak, click here.

Because the bug's incubation period is so long - up to 70 days - officials believe many more cases will emerge in the coming weeks. Listeriosis, which can cause high fever, severe headache and nausea, is particularly dangerous for the elderly, pregnant women and those with compromised immune systems.

Most of the cases connected to this outbreak have been reported in people 50 and over.

Microbiology specialist Dr. Andrew Simor of Sunnybrook Health Sciences Centre notes that consumers worried they may have eaten Listeria-tainted meat may only feel mild symptoms, or none at all.

"In most cases, the infection is pretty mild, people might not even be aware they have it. They might have a mild flu-like illness, maybe some mild abdominal pain and diarrhea," Simor explains.

"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 Listeria-laced foods can be dangerous among those who are vulnerable to it - the elderly, those with compromised immune systems, and the unborn fetuses of pregnant women. Anyone considered high-risk who suspects they've eaten contaminated meat should see their doctor just in case.

Listeria can cause blood poisoning and potentially meningitis or encephalitis.

When diagnosed, antibiotics are used to treat the infection, and recovery generally takes two to three weeks.

"Listeria is kind of unique," says Dr. Michael Gardam, medical director of infection control at Toronto's University Health Network. "The antibiotics of choice are very simple, plain, garden-variety antibiotics that we don't use much for other things. The big drug is ampicillin and the other drug is Septra, which we use to treat urinary tract infections."

Consumers are being urged to throw out anything they deem suspicious, since there may be no way of telling whether the products in question are safe.  

What is this doing to the sale of deli meats? Some vendors are starting to notice an effect. "Today there was about three people that actually asked me about the turkey breast that we sell and the black forest ham," admits deli owner Livio Balzamo.

He doesn't carry Maple Leaf products but that hasn't stopped customers from wondering. "The only thing I can do is, when a customer comes in, I can educate them as much as I know."

Some are simply not worrying about it. "I would trust this store totally that if there was any problem at all, they would immediately take it off their shelves," assures one loyal customer.

But not everyone is quite so secure. "I got a tuna sandwich," laughs Nadia Duffey. "[It's] safer hopefully."

Find more on listeria here

Are you at risk for Listeriosis?

For more information, consumers and industry can call one of the following numbers:

Maple Leaf Consumer Foods at 1-800-568-5801
CFIA at 1-800-442-2342 / TTY 1-800-465-7735 (8am - 8pm ET, Monday to Friday).

For information on Listeria monocytogenes, click here.

Some information about listeria infection (listeriosis):

WHAT IS IT?: The bacterium called Listeria monocytogenes, often found in soil, vegetation, animal feed and feces, can cause the disease listeriosis in humans who eat food contaminated with it.

WHERE FOUND: In vegetables contaminated by soil or manure used as fertilizer; infected animals can contaminate meat; unpasteurized milk may contain listeria, and certain processed foods like soft cheeses, deli meats and hot dogs can become contaminated after processing.

SYMPTOMS: Nausea, vomiting, cramps, diarrhea, headache, constipation, persistent fever. If it spreads to the nervous system, signs and symptoms may include headache, stiff neck, confusion, loss of balance, convulsions. In newborn babies who have been infected, signs include loss of appetite, lethargy, jaundice, vomiting, skin rash, breathing difficulty.

TIMELINE: Symptoms usually appear within two to 30 days, and up to 90 days after consuming contaminated food, according to Canadian Food Inspection Agency. Average incubation period is three weeks, says Ontario Ministry of Health and Long-Term Care.

MOST AT RISK: People with weak immune systems, pregnant women. Although the infection may be mild in a pregnant woman, there could be a miscarriage, stillbirth, premature birth or potentially fatal infection in the baby after birth.

DIAGNOSIS: Blood test. In some cases, samples of spinal fluid, urine or amniotic fluid may be tested as well. 

TREATMENT: Antibiotics. 

FOOD SAFETY:

• Keep foods out of temperature danger zone (between 4 C and 60 C; keep refrigerator at 4 C or colder).
• Thoroughly cook or boil foods such as hot dogs and poultry products until they are steaming hot.
• Avoid raw, unpasteurized milk or food made from it.
• Buy only as much product as will be consumed in one to two days.
• Wash raw vegetables thoroughly before eating.
• Wash hands before, during and after handling any type of food, especially raw meat and poultry.
• Clean all utensils, cutting boards and work surfaces with a mild bleach solution before and after using.
• Separate utensils for raw and cooked foods.
• Follow "use by" dates especially on packaged goods with a long shelf life.

Sources: Canadian Food Inspection Agency, U.S. Centers for Disease Control, MayoClinic.com

Recall Information

The following ready-to-eat meat products bearing an Est. # 97B are affected by this alert:

McDonald's Sliced Cooked Turkey Breast
6 x 470g
UPC - 10063100263659
Product code - 26365
All best before dates up to and including 08SE30

(Note: McDonald's has announced it's temporarily pulling its Turkey BLT from its menus in Canada until the issue is resolved. Mr. Sub has also pulled the affected meats.)

Schneiders Bavarian smokies
8 x 1kg
UPC - 0 64844 02105 8
Product code - 02106
Dates up to and including 08OC28

Schneiders Cheddar smokies
8 x 1kg
UPC - 0 64844 02124 9
Product code - 02126
Dates up to and including 08OC28

ML Sure Slice Roast Beef
3 x 1kg
UPC - 10063100213333
Product code - 21333
Dates up to and including 08SE30

ML Sure Slice Combo Pack
3 x 1kg
UPC - 10063100213883
Product code - 21388
Dates up to and including 08SE30

Deli Gourmet Roast Beef Slices
6 x 1kg
UPC - 10000000602430
Product code - 60243
Dates up to and including 08SE30

Mr. Sub Seasoned Cooked Roast Beef
12 x 500g
UPC - 10063100023567
Product code - 02356
Dates up to and including 08OC07

MSD Roast Beef, Seasoned and Cooked
6 x 500g
UPC - 10063100427068
Product code - 42706
Dates up to and including 08OC07

ML Sure Slice Turkey Breast Roast Slice
3 x 1kg
UPC - 10063100213340
Product code - 21334
Dates up to and including 08OC14

ML Sure Slice Corned Beef
3 x 1kg
UPC - 10063100214446
Product code - 21444
Dates up to and including 08OC14

MSD Montreal Style Corned Beef
6 x 500g
UPC - 10063100449381
Product code: 44938
Dates up to and including 08OC14

ML Sure Slice Black Forest Style Ham
3 x 1kg
UPC - 10063100214408
Product code - 21440
Dates up to and including 08OC21

ML Sure Slice Salami
3 x 1kg
UPC - 10063100214477
Product code - 21447
Dates up to and including 08OC21

ML Sure Slice Smoked Ham
3 x 1kg
UPC - 10063100213319
Product code - 21331
Dates up to and including 08OC21

Schneiders Deli Shaved Corned Beef
8 x 200g
UPC - 0 62000 48019 0
Product code - 48019
Dates up to and including 08OC21

Schneiders Deli Shaved Smoked Meat
8 x 200g
UPC - 0 62000 48020 6
Product code - 48020
Dates up to and including 08OC21

Schneiders Deli Shaved Smoked Ham
8 x 200g
UPC - 0 62000 48016 9
Product code - 48016
Dates up to and including 08OC21

Schneiders Deli Shaved Smoked Turkey Breast
8 x 150g
UPC - 0 62000 48018 3
Product code - 48018
Dates up to and including 08OC21

Schneiders Deli Shaved Fully Cooked Smoked Honey Ham
8 x 200g
UPC - 0 62000 48017 6
Product code - 48017
Dates up to and including 08OC21

Burns Bites Pepperoni
12 x 500g
UPC - 0 63100 21360 2
Product code - 21360
Dates up to and including 09JA01

ML Turkey Breast Roast
12 x 1kg
UPC - 10063100991583
Product code - 99158
Dates up to and including 08SE30

FS Roast Beef Cooked, Seasoned
4 x 2.5kg
UPC - 10064875713301
Product code - 71330
Dates up to and including 08SE30

FS Corned Beef, Smoked Meat
4 x 2.5kg
UPC - 10064875713318
Product code - 71331
Dates up to and including 08SE30