Is milk safe to drink? Can you catch bird flu from beef? What to know about H5N1 cattle outbreaks

Confirmation that a dangerous form of bird flu is circulating among U.S. dairy cattle has raised questions among dairy producers — and consumers — on both sides of the border.

Dairy and beef farmers are implementing biosecurity measures to keep H5N1 out of their herds, while Canadians are understandably concerned about what these outbreaks could mean for food safety.

So what is the scope of these dairy cattle outbreaks, and how is Canada impacted? And is it safe to consume milk and other dairy products?

What's happening with the U.S. bird flu outbreaks?

In the last week, American officials have identified highly pathogenic avian influenza, or H5N1 bird flu, in roughly a dozen dairy cattle herds across six states: Idaho, Kansas, Michigan, New Mexico, Ohio, and Texas.

Scientists told CBC News it appears to be the first time H5N1 has infected cows. But the outbreaks weren't entirely unexpected. Bird flu exploded globally two years ago, and numerous wild and domestic animal species have been infected, including chickens, goats, and other farmed animals.

There have been sporadic human infections, and deaths, including a mild case in Texas in an individual who had contact with cattle — the second-ever bird flu infection reported in the U.S.

While the dairy cattle outbreaks are new and raise important questions about spread across species, outbreaks among poultry are far bigger.

More than 80 million U.S. chickens have been affected by H5N1 across 48 states, the latest U.S. Centers for Disease Control and Prevention (CDC) data shows.

And Canada is experiencing a similar issue, with at least 11 million birds impacted country-wide, according to federal figures.

Is there bird flu among Canadian cows yet?

Not that we know of, though both farmers and federal officials are watching for it.

So far, the Canadian Food Inspection Agency (CFIA) has not detected H5N1 in dairy cattle or other livestock in Canada, and is "monitoring the situation closely," the agency said in a recent statement.

But bird flu experts suspect it's heading our way — or already here.

"There's no reason to think that there would be infected birds near cattle in the U.S. and not in Canada, especially when you have multiple states infected," said Dr. Scott Weese, a veterinarian and researcher with the University of Guelph Ontario Veterinary College.

"So it's not unreasonable to think that we've had infections in Canada."

Is it safe to drink milk, or eat beef?

The CFIA said the United States Department of Agriculture (USDA) shared that bird flu virus was detected in unpasteurized milk from sick dairy cattle in some U.S. states.

It's unclear whether drinking raw milk from an H5N1-infected cow would be risky, said Weese. But studies do show raw milk can carry all kinds of dangerous pathogens such as salmonella, E. coli, and listeria, all known for causing food poisoning.

"There are lots of other reasons not to drink raw milk, so this is maybe just one more reason to stay away," he said.

That being said, there are layers of protections in place to prevent tainted milk from ever reaching consumers.

"Dairy farmers control infectious diseases on their farm by isolating sick cows from the rest of the herd, effectively removing their milk from the general supply," noted Jenna Guthmiller, an assistant professor at the University of Colorado's department of immunology and microbiology, in a social media thread.

If tainted milk did somehow slip through — in either the U.S. or Canada — it would also go through pasteurization before being sold. That specialized heating process is capable of killing any harmful pathogens, ensuring the milk is safe to drink.

And when it comes to the safety of other products, such as cheese, eggs, or meat, Weese stressed that flu viruses simply can't live for very long outside a living host.

"They're not very hardy," he said, adding that thoroughly cooking food definitely kills them.

The U.S. CDC notes that "the likelihood that eggs from infected poultry are found in the retail market is low and proper storage and preparation further reduce the risk."

As for beef, the U.S. cattle outbreaks are confined to dairy-producing cows, at least for now.

"It's not going to change my eating habits at all," said Weese.

How are Canadian dairy farmers protecting their cattle?

"Canadian dairy producers already adhere to some of the highest biosecurity standards in the world," said the Dairy Farmers of Canada in a statement.

Several Canadian dairy farmers who spoke to CBC News also said they're implementing heightened measures in an attempt to keep bird flu out of their herds.

Kirk Jackson, a beef and dairy producer in St-Anicet, Que., said the potential for water source contamination is "almost zero" as farms like his use underground water sources. Workers also ensure spilled feed is cleaned quickly, to try and avoid attracting wild birds, and visitors to the farm are not currently allowed.

Still, the next few weeks could matter a lot, Jackson added, since spring bird migration is underway, bringing more flocks back north.

Seventh-generation dairy farmer Jason Erskine, in Hinchinbrooke, Que., said his farm uses screens to keep birds and vermin away from the cows — but he's aware those measures aren't foolproof.

"They still find ways to get in," he said.

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