Labs in Canada have begun testing milk samples for the H5N1 avian influenza strain that has been spreading through U.S. dairy cows, amid fears that the infection might spread to Canadian herds.

So far, there have been no indications of infections in dairy cows, but the Canadian Food Inspection Agency is testing milk and a group of scientists from across the country are also carrying out routine testing on retail milk samples.

“We hope that by testing Canadian milk regularly from across the country over time, we are able to identify any outbreaks as quickly as possible if they were to happen here,” said Dr. Hannah Wallace, PhD, a postdoctoral research scientist in the department of Medical Microbiology & Infectious Diseases at the University of Manitoba in Winnipeg.

As of the last update on June 14th, the scientists had evaluated 72 retail milk samples from every Canadian province coast to coast. All returned negative results for H5N1.

The testing complements Canadian government coordinated testing between the Public Health Agency of Canada, Health Canada and the Canadian Food Inspection Agency (CFIA) which is testing both cows and milk samples for H5N1. Any dairy cattle imported from the U.S. to Canada must also be tested and confirmed negative for the virus before coming to Canada.

“CFIA has the ability to test large numbers of samples in one batch while we are aiming to test fewer samples but on an ongoing basis. It’s imperative that academic and government partners work together on infectious disease outbreaks and if we were to detect any positive samples in the future, our first call will be to CFIA,” said Wallace.

The virus which has also been detected in cats, mice and a small number of people has now been detected in dairy cow herds in a dozen states, with the outbreak showing no signs of slowing down. But is it inevitable that the virus spreads to Canadian herds, too?

“With proper testing and protocols for containment, I don’t believe it’s inevitable but it is a possibility,” said Dr. Jordan Wight, PhD, who is also running the testing at the University of Manitoba “Which is why testing and monitoring is so important so if it does happen, we can catch it early and respond appropriately.”

It is currently not known whether infected dairy herds in the U.S. are directly infecting others, or whether all of the dairy herds are being infected by close contact with infected wild birds.

“Since H5N1 is primarily transmitted by wild birds (who of course don’t follow human-made borders), the risk of a bird transmitting the virus to cattle in Canada is an ever-present possibility,” said Wallace.

According to recent statistics, there are over 1.3 million dairy cattle in Canada spread across 9,443 farms and the industry is expected to be worth $15.58billion (U.S) in 2024.