Bird flu continues spread through cattle, but experts say risk to people is low

Regulators are watching the virus for any mutations, however.

By Michael MarksMay 3, 2024 12:07 pm, ,

It’s been about a month since dairy cows in the Texas Panhandle tested positive for avian flu. Since then, the virus has spread through cows around the country, as well as to other kinds of mammals –  including humans.

Regulators are keeping a close eye on how this version of avian flu spreads. They’ve found benign remnants of the virus in milk on grocery store shelves, and will soon start testing ground beef as well.

Dr. Keren Landman is an epidemiologist and a health reporter for Vox. She spoke to Texas Standard about the virus’ risk to humans. Listen to the interview above or read the transcript below.

This transcript has been edited lightly for clarity:

Texas Standard: A few people who work on dairies where avian flu has been detected have come down with the virus themselves. At the moment, does avian flu pose a significant risk to people?

Keren Landman: It doesn’t seem to right now.

I think one of the things that would worry folks a lot more about the risks that it would pose to people is if we saw that it was spreading easily between humans. The way that our federal agencies are currently looking for that is by basically looking for a bump in the number of sort of people turning up with flu symptoms in places where there have been transmissions among dairy cows and herds, and they’re not seeing that.

Also, obviously, the concern is that because this spreads among cows through their milk, which seems to have a pretty high viral load, that it might spread to humans through milk and beef products. And also the testing that has been done on those kinds of products to look for that possibility is pretty reassuring. We’re not seeing a virus that can grow, spread, infect living creatures in the milk.

So right now it does not seem like the viruses is a high risk to humans.

I feel like we’ve all become sort of armchair epidemiologists since the COVID pandemic. And we know about mutations. Is it possible that this could mutate and become more dangerous to humans? Is that a real concern?

Absolutely. And I think the “coulds” in this virus – the possibilities that it could become something that easily spreads among humans and causes severe human disease – are what scare a lot of flu experts.

Flu is a particularly shifty virus. So, you know, these sort of “Franken-flus” that come out of pigs or other, what we call sort of “mixing vessels” where they’re these animals are great at getting co-infection with multiple flu viruses… Flu can acquire all kinds of new abilities to do all kinds of things. And that’s what worries us about animal flu infections typically.

So yes, that could happen, but we don’t currently have signs that it is happening. What we want to prevent are the opportunities for flu to mutate in that way in order to acquire those new abilities.

All right. So leaving the “coulds” to the side for now, when we think about what’s on the grocery store shelves right now, should folks be changing their habits or buying anything different, or should they still feel confident that the dairy products they’re buying are safe?

So I think there are lots of good reasons unrelated to flu for us to think about what we’re consuming, especially when it comes to animal products. But when it comes to flu, I think our food supply is very likely safe.

We have good reason to believe that pasteurization, the same process that we’ve been using for decades – actually, probably about a century in the United States – to keep our dairy products and other products safe for mass consumption… Those have worked on previous studies of other enveloped viruses to make sure that those viruses are not able to be spread by the food supply. The studies that have been done so far have not included H5N1 flu specifically until this outbreak. And the number of products that have been tested are in the hundreds, not in the thousands or millions.

So far, it does seem that pasteurization works to keep our food supply, at least the pasteurized food supply, safe from H5N1 transmission. You know, we’d love to see more products tested. And, I think it would also really be wise for people to not consume unpasteurized milk and products made from unpasteurized milk, because all bets are off when it comes to those product’s ability to transmit viruses and lots and lots of other pathogens that cause some really serious human disease.

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