Canadians should have known earlier about the listeria outbreak — linked to a meat plant — that has killed at least 16 people, according to the medical director of Ontario's public health laboratories.

Interviewed for a CBC-Toronto Star investigation, Dr. Donald Low, who oversees 12 laboratories including the largest one in Toronto, said the crisis has exposed serious cracks in the public health safety system.

Listeria testing timeline

July 16: Toronto Public Health receives its first report of a listeria case in a nursing home.

July 21: Second report comes from the same nursing home, a rare occurrence that raised alarm bells for local health officials, because it suggested there was problem beyond the normal, background level of listeriosis.

July 24: Meat samples from Toronto arrive at Health Canada lab in Ottawa for listeria testing.

Aug. 5: Eleven days later, results come back positive for listeria.

Early August: Samples sent to Public Health Agency of Canada's National Microbiology Laboratory in Winnipeg for genetic fingerprinting tests to see if the strain of listeria in the meat matched that from blood samples of victims.

Aug. 17: Canadians officially warned through national recall of processed meat products from Maple Leaf Foods plant in Toronto.

He said the laboratory that in July received the blood samples of two suspected listeriosis victims from the same nursing home was ill-equipped to make an initial link between those first two samples it tested.

"If we had at that time in place a typing system, we would've let the nursing home know, the physician know and we also would've let public health know, and then they could've responded to it," said Low, medical director of the Ontario Public Health Laboratories, where 600 staff handle four million specimens a year.

As it was, it took three weeks for a connection to be made between the two cases and the tainted meat that ignited them.

Listeriosis is a food-borne illness caused by Listeria monocytogenes bacteria. A single strain linked to the 16 deaths has been traced to a Maple Leaf Foods meat processing plant in Toronto, prompting a nationwide recall of its meat products.

Low said the Ontario lab waited until it was contacted by local officials to confirm whether listeria was the culprit — at which point isolates were sent out to the National Microbiology Laboratory in Winnipeg to identify the genetic strain.

"That's where the delay came in," he said. "I think we have to take responsibility for that delay."

The practice of waiting for confirmation from the national lab assumes the Ontario lab is ill equipped to handle the testing, which was the case during the SARS outbreak in 2003. The Ontario lab has recruited 11 experts to do the specialized testing, which they started doing this week.

How delays happened

After the first person in a nursing home was sick, there was a delay of three or four days before the second became sick, saw a doctor, and had a blood test that showed listeria, which added up to a week.

When the second report from a nursing home was received in July, Dr. Donald Low, medical director of Ontario's public health laboratories, said the Ontario lab should have been doing genetic fingerprint typing tests immediately as the samples were received, instead of waiting for reference labs in Ottawa and Winnipeg.

"If [the two samples] were related, with that testing maybe we could have interfered, maybe we could have prevented further cases, maybe that horse had already left the barn," Low told CBC's Metro Morning.

Low called it "unacceptable" that samples were sent away for testing when the Ontario lab had hired people with the expertise to do it sooner.

"Once an event happens, once there is a break like this that allows listeria or some other pathogen into the food chain, unfortunately, it's only when people get sick that you actually become aware of it."

It should be the other way around, with the Ontario lab identifying that the strains were genetically related — the sign of a problem — and alerting local officials, Low said.

Valuable time, and possibly lives, could have been saved by doing the tests for listeria in the Ontario lab instead of waiting for the national microbiology lab in Winnipeg to identify the bacterial strain, according to Low.

If the system had been functioning as it should, he said, it should have been a few days, not weeks, before the link between listeria and the tainted meat from the Maple Leaf plant was made.

In comparison, during this summer's salmonella outbreak in the U.S., genetic fingerprinting was completed and public warnings were issued in a few days.

In an interview with the Toronto Star, Dr. Andrew Simor, head of microbiology and infectious diseases at Toronto's Sunnybrook Health Sciences Centre, agreed.

"The reality is, [the testing] that is done could be done by any reference lab, and in particular, in my opinion, should be done in a reference lab such as the public health lab we have here in Ontario."

As of Thursday evening, 43 cases of the disease have been linked to the outbreak and 19 more are under investigation, the Public Health Agency of Canada reported. A long list of products made at the plant have been recalled.

In the 16 deaths, listeriosis has been determined to be the underlying or contributing cause; another five deaths are under investigation as to whether listeriosis caused or contributed to them.

Symptoms of listeriosis — which include high fever, severe headache, neck stiffness and nausea — can occur up to 70 days after consuming contaminated food, though the average incubation period is 30 days.