Achi news desk-
While federal officials say there is still no sign of a dangerous strain of bird flu in Canadian dairy cows, scientists warn that limited surveillance means Canada may not stay ahead of an explosive outbreak of H5N1 among dairy cattle to south of the border.
So far, dozens of herds across different US states have been infected with this type of influenza A. Although it appears to cause milder infections in cows, H5N1 has also been linked to staggering death rates of 50 percent or more in other species, including various birds, cats and even human beingsalthough more data and research is needed to fully understand the risks.
“I think we’re way behind the virus,” warned Matthew Miller, an immunologist and vaccine developer with McMaster University, who is among the Canadians working on H5N1 research.
Without “a robust national surveillance program, there’s no way to know if there are infections here or not.”
The Canadian Food Inspection Agency (CFIA) told CBC News on Monday that it has yet to detect this type of bird flu in dairy cattle – or any other livestock – in Canada. (In birds, however, the disease already exists wide across the countryaffecting estimation 11 million birds are farmed so far.)
The disease is federally reportable in any species, including cattle, the CFIA said. The agency requires dairy producers to monitor for signs of infection, follow biosecurity measures, and contact their local CFIA office if there is a “high degree of suspicion” of the disease.
It appears that cross country trade is still allowed. Asked whether dairy cattle can currently be transported between the United States and Canada, the CFIA said the World Organization for Animal Health “does not currently recommend restrictions on the movement of healthy cattle and their products.”
In addition, following the US federal order last Wednesday requiring H5N1 testing for many dairy cattle moving between states, “Canada will also require testing for [avian flu] on dairy cattle imported from the United States,” the CFIA said.
When asked about testing milk samples, the agency said if H5N1 is found in Canadian cattle, it would help provide testing support.
(The agency was more clear in an earlier statement on social media(saying that it “is not currently testing raw or pasteurized milk,” adding that the virus is not a food safety concern.)
Multiple Canadian scientists, however, stress that widespread testing and surveillance efforts should already be underway rather than ramping up after a first detection.
Canada needs ‘active surveillance’
Canada “absolutely should be doing active surveillance for H5N1 in cattle,” said animals and other people in close contact with them, Dr. Isaac Bogoch, an infectious disease specialist with the University of Toronto Health Network, in correspondence with CBC News.
He said those efforts could include a range of methods such as wastewater surveillance, blood sample studies and nasal swabs.
The goal should be “all-in prevention,” Miller said, adding that “a pandemic always has the highest risk of occurring when we have a virus in animals that humans are highly susceptible to.”
Given the unprecedented jump of H5N1 into cattle, followed by explosive cow-to-cow spread across the US in just weeks, the potential for human-to-human transmission seems more likely as the virus adapt to more mammals, he warned.
“If we see more human infections, the cat is out of the bag, it’s way too late,” Miller said. “We need to spare no effort, and no expense, in doing everything to prevent even those initial infections in humans — because the stakes are just too high.”
The United States has reported one human infection linked to the cattle outbreak so far, in an individual whose only symptom was eye irritation. However, some scientists have warned that there are likely to be more that are not being detected, amid growing calls for mass testing on farms.
A person in Texas who had close contact with infected dairy cattle has been diagnosed with bird flu. This is the country’s second known human case after the virus was first discovered circulating among dairy cows across at least four US states.
“Since the matter in the [U.S.] appears to be more than we thought and brewing before it was recognized, and since we have a plausible pathway for exposure here, we should be proactive,” said Dr. Scott Weese, professor at the Ontario Veterinary College and director of the University from the Guelph Veterinary and Public Health Centre.
At the very least, he added, that would mean milk surveillance. It may not be particularly sensitive — the milk supply is diluted because it comes from so many farms, Weese said.
“But if there are positives, we know we have and then we need to look more aggressively at farm level.”
Although sick cows are being pulled from production lines, U.S. Food and Drug Administration officials said its recent national survey of milk sold on store shelves found H5N1 viral remains in one in five samples. (More encouragingly, federal testing suggests pasteurization—a heating process meant to neutralize harmful pathogens—makes milk safe to drink.)
On Monday, the US Department of Agriculture (USDA) also announced that there will be testing of ground beef in states with bird flu outbreaks, and recently warned that the virus may be passing back and forth between cattle and poultry farms.
The outbreak officially spread to 34 herds, 9 states
The first cattle known to be infected with H5N1 were reported at the end of March. Since then, at least 34 herds across nine US states have been affected, and scientists suspect that the outbreak is already much larger than official figures suggest.
Newly released research from the US Centers for Disease Control and Prevention also showed profound effects on farm cats — with a death rate of about 50 percent among those fed raw milk products from infected cows.
The study raises “new concerns about the potential for virus spread within mammal populations,” the team continued.
A Quebec poultry farmer is taking extra precautions to protect his livelihood and livestock as the province grapples with an outbreak of bird flu that has killed nearly a million birds in the past year.
On Monday, other US researchers shared a preprint — research not yet formally published or peer-reviewed — outlines efforts to monitor influenza A at dozens of wastewater sites this spring.
The team tested samples from three factories where there was an increase in influenza A in the spring, and found a marker for the H5 gene in all three facilities. Those plants were also located in an unnamed state with confirmed cases of H5N1 among dairy cattle, and two of the facilities were releasing animal waste and dairy byproducts into sewers, the researchers noted.
It all paints a picture of a rapidly spreading outbreak affecting new species, appearing in new areas, and likely beyond the point of containment, several scientists agreed external.
Funding, need help with testing
Here in Canada, funding and support for vets and farmers needs to prove clear, Weese stressed.
“If farmers have to pay for sampling and testing, and don’t know what will happen if it’s positive, and have no direct personal benefit from it, why would they do it voluntarily?” he inquired. “We need a clear program that supports good testing and that supports farms.”
Toronto-based infectious disease expert Dr. Allison McGeer of Sinai Health System said she “personally hopes we don’t get caught off guard” here in Canada.
What’s encouraging, McGeer added, is that Canada has robust human testing in place to catch serious flu infections. Typically, he said, Canadian hospitals use combined viral tests — for COVID, influenza and RSV — that can pick up a specific protein that is stable across all types of influenza A.
If a human infection from bird flu appeared in a hospital, the test would label it as “influenza A, subtype not detected,” he explained. And if the patient had also been in contact with poultry or wildlife, that combination of factors could trigger additional lab work to identify the specific type of flu – including H5N1.
But that’s only if someone is sick enough to visit a healthcare facility.
“It’s not a perfect system,” McGeer acknowledged, “but it is [a sensitive system] for detecting severe disease from H5N1.”
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