Keith Poulsen on Monitoring Bird Flu in the Dairy Industry

Zac Schultz:
Switching to agriculture news, a strain of avian bird flu has been found in dairy cows and confirmed in herds in nine states. It has not been found in Wisconsin, but it is in Michigan. And researchers from UW-Madison are helping to monitor the spread. Joining us now is Dr. Keith Poulsen, director of the Wisconsin Veterinary Diagnostic Laboratory. Thanks for your time today.

Keith Poulsen:
Thanks for having me.

Zac Schultz:
So this particular strain of avian bird flu is called H5N1 and you’ve been tracking it since 2022. Is it spreading faster now?

Keith Poulsen:
Well, this particular strain since 2022, it’s spread in the migrating wild bird population, has actually been the worst foreign animal outbreak in U.S. history. It’s killed over a hundred million birds and really back in 2022 when we were just coming off COVID, it was affecting raptor species like bald eagles and snowy owls. Then we noticed it was in our mesocarnivores, like fox kits or other scavengers, and we’ve seen that even now with the seals that are eating dead birds off the coast of Washington state. But what really changed in the last five or six months was that we’ve noticed that it has now come into our dairy cattle population, which is a very novel event.

Zac Schultz:
So testing right now is limited to cows that are transported over state lines, but your report says that’s 50,000 cows a week. So how soon before that just overwhelms and people maybe stop testing?

Keith Poulsen:
Yeah. Great question. I do think that testing will ramp up even further before we get out of this outbreak, but that’s the best way that we control animal diseases, is movement across state lines with the state animal health officials, but I do think that Wisconsin is a little bit different than this one particular business model that moves a lot of lactating cows, because that’s our biggest risk right now from what we know. We’re only a couple months into this, so our biggest risk is really lactating cows. Wisconsin doesn’t move a lot of lactating cows into the state. We tend to move pregnant two-year-olds as they’re being raised in the hot, dry climates and then we bring them back. It’s really a higher risk of really moving young lactating dairy cows.

Zac Schultz:
Since going from birds to mammals, H5N1 has also, as you mentioned, foxes, seals. I saw a report about farm cats, possibly. One person in Texas who was exposed got conjunctivitis. Is the big fear that this turns into a COVID-19 transmission where it jumps into a human population?

Keith Poulsen:
Yeah. On the public health side, we’ve known about 40 different mammalian species that have been from eating or drinking raw milk on the farms. They present very differently than our dairy cows. They present with neurologic disease. Our dairy cows present being off feed and then they drop in milk production, but really when you look at it from a 30,000-foot view is on the public health side, we know that influenza viruses change. They reassort. That’s why we have a different flu vaccine every season. We have to remember that the barriers to moving into people where it becomes like a pandemic, potential pathogen, they’re very high. There’s a lot of areas that would prevent that, but it’s not a zero risk, and the longer we don’t have good risk mitigation and there’s more virus in the environment or circulating in the cows, the higher that risk becomes that the virus will continue to reassort.

Zac Schultz:
So you’ve also found genetic material in milk, but you say that right now there’s no evidence that a pasteurized milk presents any problems to someone consuming it, but raw milk is actually quite popular and growing in popularity. Is there a risk there?

Keith Poulsen:
Absolutely. As a public health expert and all of public health, whether they’re veterinarians or MDs or just our rural health practitioners, is that raw milk products. I grew up drinking raw milk on the dairy, right? And when we were talking about growing up between Waunakee and DeForest but my kids don’t. And so the biggest population of raw milk drinkers tend to be highly educated and upper middle class, but because they’re living in urban environments, it’s not a great idea to be consuming raw dairy products at this time. The Pasteurized Milk Ordinance from 1926 has really decreased food-borne disease from raw dairy products and we need to maintain that now.

Zac Schultz:
So what should farmers be looking for?

Keith Poulsen:
So definitely need to have regular conversations with your herd veterinarian. So we’re looking for cows that are usually second lactation or greater, so they’re 3 to 4 years old, and then they tend to be mid- to late lactation, so 150 days in milk or since they’ve calved and they tend to drop in their feed consumption. A lot of cows wear rumination monitors to see how their GI motility or they wear pedometers just like I’m wearing a smart watch to know how many steps I’ve taken, and when I don’t feel well, I don’t take enough steps. Typically the computers will pull them out. Then the parlor software will monitor a drop in milk and it will automatically sort them. Those cows tend to have a fever then when they’re looked at but then they recover in about 10 to 12 days. So, really, we look at peak incidents on farm, which goes up to 10% at four to six days. Incidents drops about ten to 14 days and then the herds are recovered usually between 20 and 45 days after infection.

Zac Schultz:
All right. Dr. Keith Poulsen, thanks for your time.

Keith Poulsen:
Thank you for the opportunity.