Canadian scientists launch early warning system to spot traces of H5N1 bird flu in milk

It all started with a few text messages in late April.

Several well-known Canadian scientists — Toronto-based infectious diseases specialist Dr. Isaac Bogoch, Saskatoon-based virologist Angela Rasmussen and Winnipeg-based microbiologist Jason Kindrachuk — were all chatting about the unprecedented outbreak of H5N1 bird flu in U.S. dairy cows.

By then, American officials had tracked cow cases for roughly a month, and harmless viral particles were showing up in processed, pasteurized milk. 

But on this side of the border, the Canadian Food Inspection Agency (CFIA) was clear its team wasn't yet undertaking milk testing.

The trio of Canadian academic researchers saw a missed opportunity.

"I think we all were thinking independently: Why aren't we doing milk testing?" recalled Kindrachuk, an associate professor at the University of Manitoba. "If we can simply get milk off the shelves and [run tests], this would seem like a great initiative for us to undertake."

Rather than waiting for the government to launch that kind of surveillance, the scientists spearheaded a coast-to-coast initiative to watch for H5N1 in Canadian milk. 

"Within the span of about two minutes … we had a flurry of emails out to partners and collaborators across all the provinces," Kindrachuk said.

The result, unveiled through an unpublished preprint paper shared online on Wednesday, is what the team dubbed the Pan-Canadian Milk Network. Eighteen scientists in total worked on the findings, from universities throughout Canada. The researchers say the goal is to continue to test milk to spot any fragments of this virus showing up in the Canadian milk supply. 

That outcome wouldn't pose a risk to consumers — as testing shows pasteurization ensures milk is safe to drink — but it would signal infections in Canadian dairy cows. (Cases of bird flu in U.S. cows have led to high fevers, severe dehydration, aborted calves and a substantial drop in milk production, while exposing a rising number of farm workers to this virus.

"Our network and testing will act as an early warning system which will enable rapid responses necessary to contain an outbreak should any samples test positive," the team wrote.

As of May 24, the researchers have tested 18 retail milk samples from five provinces (Newfoundland, New Brunswick, Quebec, Manitoba and Alberta) and all came back negative for influenza A, the virus family of which H5N1 is a member.

Though government officials initially opted not to pursue milk testing, the CFIA announced its inclusion in surveillance efforts in early May, as CBC News previously reported.

The CFIA also beat the independent team to public results, releasing their preliminary data in mid-May. Full results of their first testing round — looking at roughly 300 retail milk samples from across Canada — were published online a week later.