Toronto health officials told Canada's food inspection agency to warn the public several days before it announced a link between Maple Leaf deli meats and a deadly nationwide listeriosis outbreak, CBC News has learned.

Toronto Public Health employees investigating suspected listeriosis cases had gathered enough evidence by Aug. 14 to make a connection between Maple Leaf Foods deli products and the illnesses, the department's associate medical officer of health told the CBC and the Toronto Star this week.

"It seemed that there was a connection between Maple Leaf deli meat and illness," said Dr. Vinita Dubey.

In a conference call with members of the Canadian Food Inspection Agency on Aug. 14, Toronto officials told the agency they had enough evidence to make a connection and pressed the CFIA to warn the public about Maple Leaf products.

CFIA officials, however, said they needed to wait for one more set of test results from unopened meat packages.

"We were suggesting at least, you know, do we need to message anything? Who else is at risk? But this is the level of scientific rigor that CFIA requires," Dubey said.

"They wanted to collect further samples and wait."

While the CFIA had identified listeria bacteria at the Maple Leaf Foods meat processing plant in Toronto and even begun an investigation of the company by that time, the federal agency said it wanted definitive test results to see whether it was the same strain as the one responsible for the outbreak.

The agency issued a health hazard alert on Aug. 19 warning the public not to serve or consume several brands of ready-to-eat deli meat products, including Maple Leaf, which had already begun voluntarily recalling the affected products.

By the time the agency announced that tests had firmly established a link between the listeriosis outbreak and Maple Leaf products on Aug. 23, the company was in the midst of a $2-million voluntary recall of more than 20 different products and had temporarily closed the Toronto plant to re-evaluate its food safety procedures.

Federal officials by that time had confirmed four deaths and 21 other cases linked to the listeriosis outbreak.

Agency says it needed hard, scientific proof

The CFIA declined a request for an interview with CBC News. The agency maintained that it requires hard scientific proof before it can recall food or issue warnings to the public.

Toronto Public Health said it had gathered plenty of evidence during July and August that linked Maple Leaf meat products to the outbreak, including:

• two deaths linked to listeriosis
• more cases being reported
• meat samples from sandwiches tested positive
• samples from opened meat packages were taken
• Maple Leaf notified its distributors it was being investigated by the CFIA

During a 2005 outbreak of salmonella found in bean sprouts in Kingston, Ont., regional health officials didn't wait for definitive proof to issue their own recall.

"I think it's a less desirable approach, from the point of view of the people we serve, to say, 'We'll have to wait and have confirmation before we can intervene,'" said Dr. Ian Gemmill, the medical officer of health for the Kingston Area Health Unit.

The number of confirmed deaths linked to the listeriosis outbreak has risen to 20 since federal officials announced the first death on Aug 20. Fifteen of the deaths have occurred in Ontario, two have been in B.C. and one each in Alberta, Quebec and New Brunswick, according to federal figures.

Six deaths across the country are still under investigation.

In the aftermath of the outbreak, some experts say the CFIA's mandate needs to be revised so that the agency does not serve a dual role of protecting public health at the same time that it promotes trade and biotechnology.

"We need to revisit the CFIA's mandate and try to separate the industry interest with consumer interest, supply and demand," said Sylvain Charlebois, an assistant professor in marketing at the University of Regina.

"We can't have one agency addressing both at once."

Listeria monocytogenes can be found in unpasteurized dairy products, raw vegetables and meats, and processed foods, including deli meats and hot dogs. Ingesting the bacteria can cause serious illness, including brain and blood infections that can lead to death. The elderly, infants and people with compromised immune systems are the most vulnerable.

Some of the flu-like symptoms of listeriosis are nausea, vomiting, diarrhea, severe headaches, stiff neck and fever. It can take up to 70 days for symptoms to appear after the contaminated food is consumed.

A total of 191 items produced at Maple Leaf's Toronto plant were recalled during the crisis, costing the company an estimated $20 million. The plant was reopened last month.

With files from the Canadian Press