First U.S. Bird Flu Death Raises Concerns About Preparedness

FLORA LICHTMAN: This is Science Friday. I’m Flora Lichtman. This month, the US reported its first death from bird flu, a patient in Louisiana. Back in November, a teenager in Canada was hospitalized and in intensive care with the virus. And last year, more than 60 people were diagnosed with the virus in the US, according to the CDC. That’s up from just one case in 2022. Now, just to add a little context, H5N1 Avian Influenza has been circulating globally in birds, and even some mammals, for many years. But alarm bells went off when the virus turned up in dairy cattle last year.

And since then, over 900 herds have been affected, according to the CDC. So I’m sure many of us are having COVID flashbacks. I know I am. But is that the right way to think about this? How alarmed should we be? What steps should we be taking? Here to tell us more are two influenza experts who have been following the situation closely. Let me introduce my guests. Dr. Seema Lakdawala is Co-director for the Center for Transmission of Airborne Pathogens, and Associate Professor studying influenza viruses at Emory University in Atlanta.

Dr. Richard Webby is the Director of the WHO Collaborating Center for Studies on the ecology of influenza in animals and birds, and a virologist at Saint Jude’s Children’s Research Hospital in Memphis, Tennessee. Seema, Richard, welcome to Science Friday.

SEEMA LAKDAWALA: Thanks, I’m glad to be here.

RICHARD WEBBY: Well, Thanks. Thanks for having us.

FLORA LICHTMAN: So this question is for both of you. Just top level, how alarmed are you? Where are you both on the pandemic alarm bell scale? Seema, let’s start with you.

SEEMA LAKDAWALA: On the pandemic risk portion of this, I’m at a moderate level. So moderate risk of it becoming a pandemic right now, in that where it is in its current form. But in my own aspect of where I am, I’m on high alert, the possibility of a pandemic, more so than I think I’ve been in the past.

FLORA LICHTMAN: OK. Richard, what about you?

RICHARD WEBBY: Yeah, it’s a tough one, but I think I’m, yeah, somewhere similar to Seema. I’m not in the pack my bags ready to head to the hills stage. But my sense of unease has increased a little bit over the past six weeks or so from where we were before, just as what this virus has been doing, and some of the things we’ve been seeing.

FLORA LICHTMAN: Well, I want to get into this. I mean, we’ve been tracking H5N1 bird flu for decades. What’s happened recently that is making you concerned?

RICHARD WEBBY: So we know some of the changes this H5 bird flu virus has to make to switch from being what is, essentially, a bird virus to being a human virus. And I was a little bit reassured, I guess, prior to the beginning of the holiday season that we really hadn’t seen much evidence that the virus was making those changes that were required for that host switch. But then investigators showed that we’re one mutation away, potentially, from a virus that bound better to the human cell than the avian cell.

Before that, I probably would have put money on it being two or three changes. So that information and then the sequencing of the virus from the case, both in Canada and Louisiana, suggested that the virus was making some changes in some of these areas of the genome that we know were important for this receptor switch, as well.

FLORA LICHTMAN: We are seeing that already. And were we seeing those in the wild strains, or were they happening within the body of these patients?

RICHARD WEBBY: We can’t answer that with 100% certainty, but I think most of the evidence suggests that these were mutations that were actually made during replication in the people.

FLORA LICHTMAN: Seema, what about you? Do you feel the same as Richard, that the last six weeks have raised new alarms?

SEEMA LAKDAWALA: Definitely, the last six weeks. And I would say, actually, maybe starting in September, October, I’ve increased my alarm. And it’s not necessarily for the same reasons Richard said. Some are similar. Really, for me, it’s the lack of a very strong response. We’ve known about this outbreak in cattle has been there since April. We’re 10 months in, and we don’t know the full extent of the outbreak. And the lack of having a really strong plan in place, having seen a lot of traction from a response perspective, increases my concern because now, we’re in flu season.

Now, we’re in the time of year where we know influenza viruses transmit more efficiently between people. Like Richard, I also agree that the cases in Canada and in Louisiana are concerning. I’m less concerned about the switch and receptor preference because it’s something we expect to happen every single time the virus is in a human. It has the potential to adapt. And it’s constantly adapting.

FLORA LICHTMAN: This virus has been showing up in sea lions, and foxes, and cats, and cattle. Are the strains circulating in these different groups of animals the same? Are they different?

RICHARD WEBBY: You can think they’re all H5 viruses. They’re all H5N1 viruses, but they’re all different combination of other gene segments. So, no, they’re not the same virus and they probably have different properties. But we’re, I think, just starting to try and understand that.

FLORA LICHTMAN: Well, that was my question. Are the strains equally likely to infect humans now, and are they– do people have the same response to the different strains?

RICHARD WEBBY: I think probably if you asked 10 influenza virologists, you’ll get six different answers on that one. The truth is, no, probably they’re not the same. But it’s something we need to do a better job of is understanding what happens with different combinations of genes.

SEEMA LAKDAWALA: Yeah, I absolutely agree with Richard. You’re going to get lots of different opinions on this, because we don’t have really great experimental data on it. What we do know, though, is that the cases from individuals who have worked in dairy parlors have been more mild in their presentation. And so the Louisiana case and the Canada case, that tended to be more severe– obviously, the Louisiana case was fatal– is a different part of the family tree than the cattle virus.

FLORA LICHTMAN: Are those cases thought to come from birds?

SEEMA LAKDAWALA: Yes. So the Louisiana case and the British Columbia case are thought to be interactions with, I believe, migratory birds, so wild birds. That, I think, is really interesting for researchers like me and Richard where we want to understand what’s driving those differences in the presentation.

FLORA LICHTMAN: Well, this maybe gets to my next question. I mean, if we look at global infections in humans of bird flu over the last two decades or so, historically, it’s been quite severe, like, nearly half of the 900 reported cases in people resulted in death. But of the dozens of people who’ve been infected in the US last year that we know of, anyway, most cases seem pretty mild. So what’s up with that? What’s going on there?

SEEMA LAKDAWALA: Yeah, I mean, I think this is probably due to a variety of factors. One, is something that my lab has been studying is preexisting immunity, in that some level of immunity that we’ve acquired in the more recent decades, perhaps, is providing some level of cross protection to reduce the severity of disease. Again, not against protecting against infection. It could also be, of course, the route of inoculation that these individuals were exposed to that the dose in which they inhaled, or where it splattered on their eyes, we’re talking about mostly dairy workers here, or the poultry workers.

Or it could be something about the virus itself. The other aspect could be that in the past, we’ve missed other infections that were more mild, and we’re just capturing the ones that were more severe.

FLORA LICHTMAN: Richard, we talked to you in the summer of 2023, so a year and a half ago now. And you told us that as a human, it was very difficult– it’s very difficult to catch this virus. Is that still true?

RICHARD WEBBY: Yeah. No, I think it is. Particularly, let’s think about even what’s going on in the dairy cattle right now. We know there’s ridiculous amount of virus in the milk of an infected cow. So the workers in these milking parlors are getting exposed to a lot of virus. And, yes, we’re probably missing a good percentage of those. But this is a virus that still would prefer to be replicating inside a bird than certainly a human.

FLORA LICHTMAN: Richard, you said that cows are carrying a lot of the virus. How much is a lot?

RICHARD WEBBY: So if you think of a 10 with eight or nine zeros after it, that’s how much per mil of milk out of these cows. So–

FLORA LICHTMAN: Is that a lot? I don’t have a frame of reference.

RICHARD WEBBY: Yeah. So I was going to say, you can probably take 10 virus particles or less to infect a mouse in an experimental study. And so that’s a lot of doses to infect a lot of different animals. If you’re a flu virus, an H5N1 flu virus, it seems that the udder of a cow is a great place to be.

SEEMA LAKDAWALA: I think this is where maybe Richard and I disagree just a little bit. Because I agree with Richard what he said in 2023. Absolutely, then the risk was really low, right? Because we’re not around birds a lot. We’re not around seals. But with cows, the interface with humans is really high. There’s a lot of interactions. And as Richard just said, there is so much virus. I mean, I think as virologists, we are shocked at the amount of infectious virus, like, 100 million particles per little milliliter of milk, and they’re milked two to three times a day.

And every cow in a dairy parlor, for most dairy parlors, I’m not saying everyone, their teats are cleaned by hand by a person, and then their teeth are fore stripped, which means squeezing them to initiate the letdown. And so these individuals are exposed to a lot of potential virus in this milk, as well as then people in processing facilities. So to me, I agree. I think this is why we’ve seen so many more infections in 2024 than we saw in 2023. And a serosurvey from the CDC said that 7% of dairy farm workers were seropositive for H5 antibodies.

And so I do think we’re missing a lot of infections. And the reason I think that’s important is because every time this virus gets into a human, it has the potential to gain properties, like Richard described about the receptor binding, but also other ones that we know are important for transmission, or we think are important for transmission. Or properties that we don’t even know are important for transmission, but are important. And that means it has the potential to continue to spread in humans.

FLORA LICHTMAN: Seema, I think a lot– like I said in the intro, I think a lot of people are thinking about this in terms of COVID, our most recent pandemic experience. And I guess, what will a March 2020 look like for bird flu? How will we know we’re there? And is that even the right question to be asking?

SEEMA LAKDAWALA: You mean like when we all went into lockdown in March of 2020?

FLORA LICHTMAN: I mean– yeah, when we knew that this was a disaster, when like, we widely knew this was a bad situation.

SEEMA LAKDAWALA: I think it’s definitely going to have a lot more human infections. Of course, that’s probably going to be when we have maybe a March 2020 situation. I think what I have been trying to focus on since I heard about this outbreak is to get us to where we’re not at a March 2020 situation, you know what I’m saying?

FLORA LICHTMAN: Thank you. Yes.

SEEMA LAKDAWALA: Yeah. I have young kids. I don’t want to be in a lockdown, again. Nobody does. Nobody wants this virus to succeed in humans. Absolutely not. And so one thing that I have been surprised by is that we haven’t taken stronger steps to control the virus in the source.

FLORA LICHTMAN: What should we be doing? Walk us through it.

SEEMA LAKDAWALA: In my opinion, some of the things we should be doing. One is a stay-of-farm order. Cows are transported so much in this country, more than I ever imagined. And they are transported across farms within a state. They are transported across state lines. So we are getting a lot of spread of this virus because cows are being transported that are not known to be infected. So number one is the stay-of-farm order. Because if we can do a stay-of-farm order, maybe we can then go in and assess the extent of this outbreak across every state in the US, across every herd, and so that we actually understand how big is this outbreak in cows.

FLORA LICHTMAN: We don’t even know that at the moment.

SEEMA LAKDAWALA: Well, we don’t even know that. No, we don’t even know that.

FLORA LICHTMAN: When we say 900 herds, that’s not actually a meaningful number.

SEEMA LAKDAWALA: That’s only 900 herds in the States that are testing.

FLORA LICHTMAN: OK.

SEEMA LAKDAWALA: Talk about COVID flashbacks, like testing. There is not universal testing of bulk milk tanks– let’s not even talk about individual cows at the moment– of bulk milk tanks across the US. That’s not happening. And then once a herd is positive, there is no information of which cows or how many cows on that herd are positive. And so let’s say the initial outbreak is 10% of the herd. And 90% of that herd is not infected. We are then just letting that virus spread to all of these potentially susceptible cows.

FLORA LICHTMAN: Right. There are interventions we could be taking is what I’m hearing.

SEEMA LAKDAWALA: Interventions we could be taking. So, of course, like PPE is also important. I have been to a number of dairy farms. And I will be honest, I see a lot of farm workers wearing gloves, but not a lot wearing eye protection or respiratory protection. And so that is a concern, of course. So PPE could be enhanced, and requirements around that could be enhanced. And vaccination, this is really Richard’s wheelhouse. This is what he does. And there are stockpiled H5 vaccines.

RICHARD WEBBY: Yeah. I think it makes a lot of sense to be at least offering the H5 vaccine we do have to these workers. Yeah. Of course, offering it and actually getting into people’s arms are two different things. And I think there’s a good experience from Finland where they actually did this. So they tried to vaccinate workers involved in the fur industry over there. They got an abysmal uptake of vaccine in those workers. So I think it’s a good idea to offer it. But there’s going to be– have to be a lot of outreach.

It’s got to have to be people who have the trust of the individuals working on these farms to say, hey, vaccinations are a good thing. It’s going to protect you, it’s potentially going to protect your family. But so– yeah, it’s not something we can say, let’s vaccinate and we’re going to get 90% of these people vaccinated tomorrow. But I think it’s something we absolutely should be thinking about.

FLORA LICHTMAN: Is there anything individual should be doing? Should I get rid of my bird feeder? Is there something that I should do to keep myself safe?

RICHARD WEBBY: So again, from my perspective, I think you’re probably fine with a bird feeder in the backyard. But you’ve got to try hard to catch. I think that’s probably still the case. So from a bird feeder in the backyard, the risk– you’re raising your risk minimally. But again, we’ve got to think this virus is widespread. It’s widespread in wild animals that, potentially, if your cat goes in and out, that cat could interact with wild birds. So you’ve just– I think people have got to be aware of the fact that the virus is out there.

If you see something that looks sick, doesn’t look right, certainly, if it’s not your own cat, take a wide berth. If it is your own cat, just think about that, as well. Perhaps, wear a little– put gloves, wash your hands, type things, talk to your vet. I say the cat, but there’s lots of other animals, as well.

SEEMA LAKDAWALA: Be careful with your sea lion, yeah.

RICHARD WEBBY: If you’ve got a sea lion out in your backyard, yes, absolutely. Just take note if it starts to sneeze.

FLORA LICHTMAN: Seema, any last thoughts?

SEEMA LAKDAWALA: Yeah. I’d add to Richard’s caution. Also, don’t drink raw milk, don’t eat raw cheeses. It’s not something that normally should be advised, anyways. But really now, it could be a way to have increased exposure to H5 and infection potential. And, yeah, don’t handle any dead animals or sick animals that you see lying around.

RICHARD WEBBY: People have been studying these H5 viruses since they really first emerged in 1997. And this batch of viruses that’s circulating globally and in our own backyard now, probably are the nastiest virus that we’ve seen in terms of ability to cause disease, either in laboratory model systems, or you think of the mass die-offs we’ve seen in the sea mammals. The number of birds that have fallen out of the sky.

So, yes, hard to catch, but it’s a virus that has a scary ability to cause severe disease. So I can’t say 10 people drinking more raw milk, they’re all going to get sick. But having seen what this virus can do, I surely won’t be drinking any.

FLORA LICHTMAN: That was very informative. Thank you, both, for joining me.

RICHARD WEBBY: Yeah. Thanks, Flora.

SEEMA LAKDAWALA: Thank you so much for having us.

FLORA LICHTMAN: Dr. Seema Lakdawala is Co-director for the Center for Transmission of Airborne Pathogens, and Associate Professor studying influenza viruses at Emory University in Atlanta. Dr. Richard Webby is the Director of the WHO Collaborating Center for Studies on the ecology of influenza in animals and birds, and a virologist at Saint Jude’s Children’s Research Hospital in Memphis, Tennessee.

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