Bird flu hits California dairy farms

MARY REICHARD, HOST: It’s Tuesday the 24th of December.

Glad to have you along for today’s edition of The World and Everything in It. Good morning, I’m Mary Reichard.

NICK EICHER, HOST: And I’m Nick Eicher.

Up first: Bird flu in cattle.

Over the past four months, hundreds of dairy cow herds in California have tested positive for bird flu. Governor Gavin Newsom declared a state of emergency to channel more resources to help dairy operators manage the outbreak. Meanwhile, the C-D-C reported the first severe human case of H-5-N-1 bird flu in Louisiana. How serious is this?

REICHARD: Well, joining us now is Erin Sorrell, a professor of public health at Johns Hopkins University. Erin, good morning!

ERIN SORRELL: Good morning, thanks for having me.

REICHARD: Well, so glad you're here. Even though we are talking about bird flu. The outbreak in California is primarily affecting cattle. How did that come about and how big of a problem is it?

SORRELL: It's a great question. You know, this virus has actually been circulating for about two years in the US and it was brought over by wild birds that were migrating as they usually do and has led to die-offs of millions of wild birds. The virus has the ability to jump species so it hopped over into domestic birds into a number of wild mammalian species and then in March of 2024 the first case was detected in a dairy, and so in terms of the number of herds that have been affected so far, it's about 865 herds in 16 states, but California has the largest number where they've got about third of the cases in terms of dairy cattle.

REICHARD: Well, how prepared is our agricultural infrastructure to manage a threat this big?

SORRELL: It's, that's another fantastic question. And I think it depends on the type of production facility. So our poultry producers in the States have been trained and untested against avian influenza outbreaks for a number of years. So the systems that they have in place for detection, response, and biosecurity at the farm are exceptional. This is the first time that we've had cases occur in dairy cattle. And so this was an unknown, it was a novel event for dairy producers. So it caught a lot of people off guard and has taken a lot of time to really figure out exposure risks, spillover risks, and how best to respond to these cases.

REICHARD: Well, you mentioned how the virus jumps species and we have seen human infections from this particular strain of bird flu, as we mentioned. Two questions here, Erin. How is it spread and how can people protect themselves?

SORRELL: So it is spread in different routes, depending on the animal that you're interacting with. So in many cases, people that are getting exposed to avian flu from handling dead or sick poultry, that could also be dead wild birds, or sick birds that might be mingling with your backyard flocks. It tends to be direct contact for an avian to human interaction. For agricultural workers, particularly dairy farmers, what we've seen in the data has been indicating is it's direct contact with infected cows and also milk. So raw milk, if a cow is infected and is being milked, will have high levels of virus. And so there is a grave concern in terms of both the agricultural workers that are milking these cows on a daily basis. And that's where we've seen high exposure rates, but also ingesting raw milk. And so that could be, you know, your average citizen that would be buying raw milk. There's been a lot of recommendations not to do so at this time.

REICHARD: Of course, the really big question on people's minds is whether we're looking at the potential of another pandemic from this disease. What do you think?

SORRELL: You know, It's a hard question to answer. And unfortunately, I don't have a good answer for you. I think that we don't know and we need more data and we need a better response. My opinion is if we can contain it in dairy cattle and if we can contain these exposures to a one -off infection, then we really can prevent any onward spread, any human to human transmission. We don't give the virus the opportunity to evolve into a pandemic.

REICHARD: I don't think it's any secret that public trust in the CDC and government health agencies is on the low side these days. How can officials address skepticism and also provide information about bird flu that the public can trust?

SORRELL: You know, I think that as the public, we have to look to the experts to provide that information, but information needs to be provided in a timely and accessible manner. So understanding the risks, if you are an agricultural worker, are very different than someone who might live far away from and not interact in any way, shape, or form with poultry or cattle. So understanding your risks and having that information communicated to you regularly, information getting updated when when it becomes available, I think is critical risk communication to the public.

REICHARD: And just to put a finer point on that, what lessons were learned from the COVID pandemic that helps us manage this particular infection now?

SORRELL: I think one of the biggest lessons in terms of communication and public outreach during the pandemic is that information changes as we learn more about a particular disease or the way it interacts within different, and in this case, different species, and being able to provide updated information that may change, guidance and recommendations might change throughout this outbreak, and being receptive to that and understanding it's because data is informing those recommendations.

REICHARD: Erin Sorrell is a Public Health professor at Johns Hopkins. Thank you so much!

SORRELL: Thank you.

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