Media Briefings

Avian influenza update

Journalists: Get Email Updates

What are Media Briefings?

Highly pathogenic strains of avian flu, or bird flu, reemerged in 2022 after going undetected in the United States for several years. Since then, the disease has killed tens of millions of birds at poultry farms in 47 U.S. states and has killed or sickened several other types of domestic and wild animals. SciLine’s next briefing will include updates from three scientists on the current avian flu situation, including the latest surveillance and monitoring efforts; which viral strains are being detected and which animal populations are being affected; and response and prevention efforts that are underway or under consideration to curb disease spread and prevent future outbreaks. Panelists made short presentations and then took questions on the record.

Journalists: video free for use in your stories

High definition (mp4, 1920x1080)




RICK WEISS: Hello everyone and welcome to SciLine’s media briefing on avian influenza, or, as the AP Stylebook casually calls it, bird flu. I’m SciLine’s director, Rick Weiss. And for those of you who are not familiar with us, SciLine is a philanthropically funded, editorially independent, free service for journalists and scientists. We’re based at the nonprofit American Association for the Advancement of Science. Our mission here at SciLine is simply to make it easier for reporters like you to get scientifically validated evidence and scientist sources into your news stories. And that means not just stories that are about science, per se, but really any kind of story you’re doing in your community, where a dose of science can make that story stronger, which is just about any kind of story you can think of. Among other things, you should know we offer a free matching service that helps connect you to scientist sources with deep knowledge on the area you’re writing about and have excellent communication skills. We do that for you on deadline. Just click on and the button that says, “I need an expert.” And while you’re there, check out our other resources for your reporting help. A couple of quick logistical points before we get started.

We’ve got three panelists today who are going to make short presentations of about 5-7 minutes each before we open it up for Q&A. To enter a question, just go down to that Q&A tab at the bottom of your Zoom screen. Enter your name and news outlet and your question. And if you want to pose that question to a specific panelist, please note that. A full video of this briefing is going to be available on our website later today, and a time-stamped transcript should be available within the next day or so. But if you need raw copy of the recording more immediately, please submit a request through that Q&A box, and we’ll send you a link to the video before the end of today. And you can also use that Q&A box for any technical questions or difficulties you’re having.

Okay, I’m not going to take the time here to give a full bios for our speakers. Those are available on the SciLine website on the Media Briefing page. I just want to tell you that you will hear first from Dr. David Swayne. He is currently an independent poultry veterinarian and a pathologist and former director of the USDA Agricultural Research Service Southeast Poultry Research Laboratory. And he’s going to give us an overview of this viral menace and some of the outbreak surveillance program descriptions. And we’re going to hear next from Nichola Hill. Dr. Nichola Hill is an assistant professor of virology, disease ecology, and global health at the University of Massachusetts Boston. She’s going to talk about avian flu in wild populations and address how avian flu is spreading throughout and between populations, and how the current outbreak compares to previous ones. And, third, we’ll hear from Dr. Yuko Sato, who is a poultry extension veterinarian and associate professor of veterinary medicine at Iowa State University, and she’s going to speak about response and prevention efforts. So, with that, let’s just get started, and over to you, Dr. Swayne.

Overview of avian influenza


DAVID SWAYNE: Thanks, Rick. So, I’m going to kind of give everybody the background about avian influenza. And first we going to talk a little bit about the cause. It’s a virus. And so, here I’ve got a couple of pictures on the right-hand side. The top one is a picture of the virus taken through electron microscopes. You can see that it’s kind of got a variable shape. They range from spherical to kind of spheroid to even elongated. These viruses are very, very small. They’re made up of RNA as their genetic material. And we categorize them as an orthomyxovirus, and its specific genus is influenzavirus type A. And each of these virus particles has, on the surface, these protein projections. The first projection is the hemagglutinin. And there are 16 different hemagglutinin subtypes, numbered from H1 to H16. Now, what I want you to remember about the hemagglutinin today is the hemagglutinin mutates, and through those mutations, it changes the virus’s properties, which can be the properties to replicate or the properties of being protected against by a specific vaccine. So, those mutations change those traits. The second protein on the surface of the virus is the neuraminidase, and we have 9 different neuraminidase subtypes, numbered N1 to N9.

The next really important point to understand is when you talk about the genetics of the virus, the genes are contained in the center of the virus on 8 distinct segments, and these 8 distinct segments are really important because we can get dual infections of the virus, in this case, a low path AI virus and a high path AI virus in the same bird and even in the same cell. And when this happens, these viruses will grow within that cell and produce these different segments. And when the viruses are produced and put outside that cell to spread, they may have different combinations of those gene segments, which really determine the ability of this virus to grow in, say, different bird species or its ability to have other traits specific for that virus. We also have a different ability for these viruses to produce disease, and we categorize them into two very broad categories. The first category is what we call low pathogenicity viruses. And these are viruses that generally grow or replicate in local areas, such as in the respiratory tract or in the digestive tract. And usually when, say, poultry are infected by these viruses, they show a mild respiratory disease with coughing or sneezing. But also in hens, chicken hens or in turkey hens, they may have a drop in egg production by flock basis. An example of this kind of a virus, you’ve probably heard, is the H9N2, which is a low pathogenic virus that’s pretty common throughout much of Asia and parts of the Middle East. But really, when you look at avian influenza viruses, the low pathogenic category can be any of the H1 to H16 hemagglutinin subtypes.

Here’s just a couple of pictures to show you what it might look like in a flock, a low pathogenic avian influenza virus infection. So, this is a turkey flock. And right in the front, you see two turkeys that are kind of hunched over, have a little bit of ruffled feathers, and their eyelids are closed. They have low pathogenic avian influenza. This is a higher magnification of just one of those turkeys, and you can see right below his eyes, you have this—these sagging structures. These are sinuses. And this infection grows really well, the virus, in the upper respiratory tract, producing mucus and also causing the cells that line the sinus to die and slough off and mix with that mucus as well as normal bacterial colonies may be present in there. In hens that lay eggs, what you will see is a change in the ability of that egg to be normal. And what you’ll commonly see is a decrease in the amount of calcium that’s deposited in that egg shell. So, the egg shells become very, very thin. They lose a lot of their color, and they may even be wrinkled on the surface or crack and break. When you look at the inside of the bird, and you look at, say, the ovary, you’ll find that there is the process we call involution going on, so blood vessels will die back. You may see areas of hemorrhage, and these ova will absorb, and that chicken or that turkey hen will quit producing the eggs.

Now, the other category as far as pathogenicity or disease production ability are the viruses we categorize as high pathogenicity, and these are the real deadly viruses. This virus spreads throughout the entire body of the chicken and—or turkey, replicating in almost every type of cell in the body. In fact, if these birds are not vaccinated, they have a chance of having mortality up to close to 100% of the birds because they cannot survive it. A good example of this kind of pathotype is the H5N1 virus that we’ve been fighting across the U.S. and Canada now into Central and South America since the fall of 2021. Now, highly pathogenic avian influenza viruses have only been seen with the H5 or the H7 subtype. However, just a caution, most H5s and most H7—that’s the hemagglutinin subtypes are really low pathogenic, and just a small percentage of them are highly pathogenic viruses. So, here’s a few pictures to show you what a highly pathogenic infection would look like. This is a chicken. You can see that the chicken is lethargic. It’s basically recumbent. It has ruffled feathers, and if you look closely at the head, you can see the head is very swollen. That’s because these viruses attack the blood vessels, producing fluid under the skin or edema as we would call it. Here’s another picture showing this chicken, and we look at the wattle and the combs. The wattle is the structures right below the beak, and the comb is on top of the head. And they have this dark coloration, this black coloration because the virus has grown in those blood vessels and kill part of the tissue.

Here’s an example of hemorrhages that are very common in high path AI infections. This is under the skin, as well as this is the heart. You can see these little red pinpoint hemorrhages in the fat along the heart. Now, avian influenza viruses can infect a wide variety of poultry as well as wild birds. But the ability to infect and grow in those species is very dependent on the individual virus strains, what we would call adaptation. Now, we know migratory aquatic birds are the reservoir of almost all low path AI viruses. That’s ducks, and geese, maybe some gulls, and other type birds. But historically, high path AI viruses are really not maintained in these wild birds until now.

So, I want to emphasize that all avian influenza viruses are not the same. And I’ve already mentioned they have different hemagglutinins. They have different neuraminidases, and they have different pathogenicities. But really another important point to remember, as I talked about mutation of the hemagglutinin, and all high pathogenic avian influenza viruses, which are H5 and H7s, they all arose from a low pathogenic H5 or H7 virus through a mutation, a very specific mutation, in that hemagglutinin molecule. Also there—the viruses are different because they have different genetic lineages for the hemagglutinin gene. For example, the virus that we are facing today in North America and our poultry and wild birds is a virus that arose in 1996 first reported in domestic geese. This we call the Goose Guangdong lineage, and because it arose in Asia, Europe flyways, we call it Eurasian lineage virus. And it has some very, very unique biology among all high path AI viruses. It can infect a wide variety of domestic poultry, including water type birds, such as domestic ducks and geese, also terrestrial type birds, such as chickens and turkeys and quail. But also it can affect a wide variety of wild bird species. The particular virus that we face today is a very unique genetic clade of the hemagglutinin is what we call a clade. And it’s very, very specific and has spread throughout five continents in the last three years. And the other thing in North America, just as an example, this virus which came in from Europe across the North Atlantic, that virus now has mixed with our low pathogenic avian influenza viruses that are present in a wide variety of our wild birds. And what’s emerged are multiple types of reassortant viruses. In fact, 87% of the viruses that are identified today in wild birds and poultry are reassortant viruses that have changed by mixing of the different gene segments.

Now, and to finish, a little bit of information about surveillance programs. So, the first question is what is surveillance? Well, surveillance is just determining where the avian influenza virus is located. That includes like doing testing in different bird populations, like we would—you could test in different populations of wild waterfowl or other wild birds. You could do testing in zoo birds or commercial poultry or poultry in the live poultry market system or backyard poultry or gamebirds. That’s one set. It could also tell us about the physical location of the viruses, such as the geographic distribution within, say, the United States, or tell us about the distribution of it in wild waterfowl flyways or in specific ecosystems. As far as in poultry, it could tell us in which production systems is it located? Is it in the meat production systems of chickens or turkeys? Or in our egg production systems? Or is it present in our hobby and backyard flocks or in our live poultry market system? Could also tell us which bird species are affected by the virus. Or it could tell us, even within poultry, if it’s a specific type of poultry. Is it in laying chickens or is it in meat type chickens? And also because we take the samples at different times of year, it can tell us about the seasonality. Is it only present in certain times of year in certain geographic locations, or is it present year long?

The next question is what kinds of samples are collected for surveillance? Well, in poultry as well as wild birds, the primary samples that are taking if you have the bird physically in hands, you take a cloacal swab or a butt swab, and the other swab is the oral swab. It’s just a swab taken from the mouth. It has a synthetic fiber on a stick, and you just walk it around. Then you put it in a vial and send it to a laboratory for testing. If birds are found that are dead, wild birds or poultry, then you can take those to a veterinary diagnostic lab where they will take tissues from those dead birds and then look for the virus in those tissues. Or you can actually look at environmental samples in poultry barns or in processing plants, or you can, in the environment that wild birds, and you can look at samples. For example, on the beach, you could pick up fecal samples and put those in a vial and send those off for testing. If you have live birds, you could also take blood samples and look for evidence of infection in those blood samples. So, what kinds of tests are used on these samples that are collected? Well, the most common test is a genetic test or a molecular test that looks for the actual avian influenza virus. And we have several different tests that helps differentiate those types of avian influenza viruses. Or if we have the blood samples, we can actually look in that blood sample for specific antibodies that would indicate to us that, in the past, this bird had had a infection by an avian influenza virus.

Now, the question is you get those samples, where do they go? Who does the testing on these samples? Well, it varies. So, for example, if you are collecting samples, that sample may come from a farmer who sees illness in his birds, or he may see death in those birds. It could be the grower on a large farm or even the owner of a farm could collect those samples and send them to a laboratory for testing. In the wild, it could be a wildlife biologist. On poultry farms, it could be the poultry veterinarian for the company or the staff, the veterinary technical staff, or that veterinarian who collect those samples. And then those samples would be sent to a specialized lab that can do the testing. Almost every state in our country has one or more state veterinary diagnostic labs, and they are part of a larger organization called the National Animal Health Laboratory Network. And they’re trained very specifically to run specialized tests such as avian influenza test and give those results back to the provider. If they suspect that there is a highly pathogenic avian influenza virus, then those samples are forwarded on to a national reference lab. And for avian influenza, our national reference lab is in Ames, Iowa at the National Veterinary Services, which is part of the U.S. Department of Agriculture. In addition, there are specialized university labs that can work with highly pathogenic avian influenza viruses. They have to meet certain criteria for that, but they also can do the diagnostics. But confirmation for high path AI is always done through the National Veterinary Services Laboratory.

I think the final question is why do we do surveillance? And there are many wonderful reasons to do that. For one is that knowing where the virus is helps identify the risks that we would have to poultry or to wild birds. And through identifying those risks, then we hopefully can develop mitigations or interventions that will help prevent the spread of that virus or help us in the control and the elimination of that virus. Thank you.


RICK WEISS: Great, thank you, Dr. Swayne for really nice plain language intro to a lot of concepts there. Over to you, Dr. Hill.

Avian influenza in wild birds


NICHOLA HILL: Great. Thanks, Rick. See. So, today I’m going to provide an update on the spread of highly pathogenic avian influenza in wild birds. I think a large, looming question for a lot of us is is this—are these latest outbreaks—do they represent a new era for bird flu? And the answer is yes. So, this is the biggest outbreak in wildlife to date of avian influenza virus. We have estimates of between 10,000 to up to 1,000,000 cases of infected wild birds globally. So, bird flu known as highly pathogenic avian influenza has been a long time in the making, and I think David did a great job of highlighting this. So, this timeline actually shows highly pathogenic outbreaks since that first mass mortality in wild birds in Qingahi Lake in China. In gray circles are all the outbreaks documented by the World Organization for Animal Health. And in green are some of the biggest outbreaks in each geographic region, ranging from Asia, Africa, Europe, and the Americas. You can see that outbreaks in Asia have been consistent over time, as this region really is considered an epicenter for the virus. And we’ve seen two introductions of highly pathogenic H5 into North America, the first in 2014 via the Pacific Coast, and the second current outbreak that has infected over 6,000 birds and counting. And we think the evolution of the virus over time from that original ancestor of highly pathogenic H5 in Guangdong, in China, and the recent emergence of clade in roughly 2011 correlated with this really marked increase in the frequency and magnitude of outbreaks.

So, why did highly pathogenic H5N1 spread to North America only recently? In short, the epicenter of the virus has expanded. So, we’ve seen that epicenter expand from Asia into Europe, and this took multiple iterations. First, we saw the westward spread from this epicenter in East Asia. So, this is the top map that you’ll be looking at. And if you cast your eye on that deep purple, that is where we think this virus really originated. And this was the epicenter in Eastern Central Asia, and then westward into the Middle Eastern Europe between 2015 and to 2017, which is shown in that lighter orange color. The next chapter involved highly pathogenic H5 becoming entrenched in Egypt. And so, that’s that map down the bottom left of your screen, in 2018, and then it spread into Eastern Europe. And finally, we’ve seen spread further into Africa. So, this is the map that’s the bottom right of your screen now, in 2021, followed by a spread up into Northern Europe. So, highly pathogenic H5N1 now has a larger spatial footprint than ever before. And this is a process that was about 10 years in the making.

So, Europe has become a jumping-off point for this recent trans-Atlantic spread into North America. So, you’re actually looking at a map that is polycentric view of the North Atlantic. So, we’ve got the U.S. and Canada over on to the left of the screen, just to orient you to it. There’s not a lot of bird surveillance that is performed in these really northern high latitude regions. But movement records of birds collected over time suggests the possibility of spread via a mix of shorebirds, gulls, ducks, and geese. So, a bit of a tag team that these are species and taxa that breed in the Arctic tundra, and they migrate along the Atlantic coast. So, we saw that first detection in North America, in Newfoundland, in Canada, in December 2021, and this was at an exhibition farm, where a great black-backed gull and poultry were infected around the same time. The first detections in the U.S. was in North and Carolina concurrently in January 2022, and this occurred in hunted wild ducks. So, after introduction, the virus really spread from the Atlantic Coast westward across the U.S. and is now being detected in all 50 states, including Alaska. So, we’ve seen continuous circulation in North America since that time, and it’s raised the question is this virus now endemic? And we’ve also seen, of course, the recent spread into South America as well.

So, do wild birds contribute to spread differently? Yes, that’s a resounding yes. So, the current stream of highly pathogenic H5N1 called clade, which refers to mutations in the hemagglutinin surface protein, as David was pointing out, that’s particularly well adapted to spread amongst waterfowl, so our ducks or geese and swans. And this is because it kills some, but it leaves some alive, and those infected birds can actually spread the virus geographically over sometimes quite really large distances. And so, waterfowl and specifically ducks are this great host ecologically speaking for the virus because they both swim, and they also fly. So, there are multiple modes of spread for the virus this way. And outside of ducks, most species are waterfowl, those that are taxonomically related to ducks. Most birds species have quite high fatality rates, compared to ducks. So, this is an indicator that the virus is actually quite well adapted or adapting in real time to these species of ducks and waterfowl. So, we have now over 150 of the approximately 1,000 bird species in the U.S. that have been infected with highly pathogenic H5N1. And this chart on the right of your screen shows on that x-axis we’ve got month since the original detection to present time. And on the y-axis, we’ve got the total cumulative number of species that have been infected. So, these are running totals, so they will increase over time. And it really indicates rapid host range expansion over the—since the original introduction of the virus, but we hope it’s actually slowing down based on this evidence that you can see that increasing trend is beginning to level off, so time will tell.

And finally, what is the risk of spillover to wild mammals? In short, mammalian species that eat or swim with birds are really at highest risk in the wild. And so, we’ve seen many of these top predators infected with high path, and these are just a few, so seals, osprey, bald eagles, red-tailed hawks, foxes, coyotes. It turns out that red foxes actually account for half of these mammalian infections, and this probably is due to foxes predating on ducks. And that’s a similar transmission pathway for our raptors, so our red-tailed hawks and our bald eagles, for example. And it’s worth noting that dabbling ducks are way down the bottom of the food web. So, a lot of animals actually prey on dabbling ducks, including humans who hunt, and this provides a possible mechanism to explain why this virus keeps spilling over into wild mammals. Currently, the USDA reports about 170 cases of wild mammals infected as of April 2023, so present time. But a different transmission route is responsible for infecting marine mammals, and that’s waterborne transmission. So, mammals that swim with birds or overlap with birds in coastal areas, such as seals and dolphins and sea lions, can become infected, resulting in these very large mass mortality events. And a recent example of that is the 3,500 sea lions that have actually succumbed to the virus in Peru. And we’ve also seen recurrent infections in pelicans and gulls and seabirds in those particular habitats. And we know that this is a different transmission route. And this is based on the fact that these virions of virus particles can actually distribute in water and then infect another animal that’s nearby, and that’s it for me. Thanks so much. I’ll turn it over to you, Rick.


RICK WEISS: Wow, an incredibly, an incredible success story, I have to say, for this virus, looking at that demonstration. Not good news, of course. Dr. Sato, over to you.

Response and prevention efforts


YUKO SATO: Thank you very much for the introduction, and I’ll kind of summarize it up at the end part, which is responsive prevention, but I will actually start with prevention. And kind of looking at the life of a poultry flock or life of a chicken flock, there’s a lot of inputs and outputs that happen in the life. And if you look at them, all these could potentially be an entryway of the virus. So, when we talk about prevention efforts for high path, the word biosecurity has been mentioned multiple times. And so, we look at it kind of as a concept. It’s a team effort between a lot of people. It’s the—it’s the farmers or the producers. It’s the state and federal portions and also the scientists, so it’s all of a team effort. You have to put all these puzzles together to make sure that we prevent the virus from entering a flock.

So, then we have some data that’s presented from USDA APHIS. There was a interim report of the epidemiologic analysis looking at how this virus has kind of affected the industry. This is published in March, and the report goes from the beginning of the outbreak in February of 2022, all the way to July. And kind of the key takeaway—it’s a pretty long report. It’s a 70-page report. The key takeaway is that 84% of these viruses that were introduced, were infected, were wildbird introductions, meaning that less than 15% of the HPAI cases in 2022 were from the farms or farm spreads. So, compared to 2015, where the narrative was actually flipped, we’ve done a really good job, actually, with biosecurity. The other key type of takeaway is that there’s more backyard flocks that are infected with this outbreak. Back in 2015, only 21 flocks were infected that were backyard poultry. And the good news is that these backyard poultry that are infected were not associated with spreading high path AI to commercial farms.

And some of the other highlights from the epi report is that the—what predicted the likelihood of a flock to contract high path is kind of what Dr. Hill has already summarized. Number one, if you see waterfowl in the fields closest to the farms, if you see 10s of 1,000s of birds around in a field close to the poultry farm, you’re more likely to get infected. The other thing is if a farm is within a control zone, and I’ll talk about it and the outbreak response, but they are more likely to be infected. What are some things that potentially are preventative? Some things that they talked about is if you had a feed spill, these foods spills were cleaned immediately. This could be a source of food for the waterfowl to come. So, kind of makes sense, right? So, something to look forward to is that there is a 1-page summary of this 70-page report that’s coming under way.

There’s some additional data analysis that’s looking at these initial turkey and commercial layer farms that were infected, trying to look at what are the things that reduce the likelihood of infection? Some of the kind of preliminary information that we’re talking about is mostly improvement in biosecurity, points like permanent ventilation installations or improvements, looking at vehicle wash stations, or employee wash stations, or some temporary or permanent wild bird mitigation strategies. Kind of goes all the way together from what the first two speakers have mentioned. Some other things to look forward to is that this report only goes up until July of 2022. So, the next set of data, since this outbreak is not over, it goes from July to March of this year. So, that epi report is scheduled to be released in the fall. So, I would keep an eye out to see what that entails.

So, now I kind of mentioned about control zone and kind of walking you through. So, if you have a flock that is infected with influenza, how does that unfold as far as an outbreak goes? So, again, the beginning of anything is that the flock has to be detected as a positive influenza premise. And from there, that cascade of events kind of happens. So, when it comes to outbreak control, it starts with detection, and then it goes to depopulation, and then disposal and decontamination. So, I call that like the four D’s of outbreak control. And I’ll talk a little bit about how—what that means. So, once we talked about the samples that David had mentioned, so you take those samples from potentially infected birds. Those samples are sent to the laboratory, and then you get a unfortunate positive confirmation of the virus. Once that virus is confirmed in a flock of birds, now that whole farm site is considered positive. So, it doesn’t matter if there’s a barn that has, let’s say, five houses of poultry houses, one house tested positive, the rest of the are four negative. That whole site has to go down. So, all five barns are supposedly depopulated. So, the term is used basically to put down all the birds on that one site. This is an emergency procedure. It’s not euthanasia. It’s an emergency depopulation of that premise. Once all those birds are depopulated, those birds have to be disposed. And then the site has to be decontaminated in order to make sure that the farm can come back into business after recovery from the virus. So, while this is going on, there’s an infected site at the middle of it. So, in this map over here, you see the X in the middle. That’s the infected farm. And once this happens, the state or the federal partners would draw basically a 10 kilometer circle, and everything within that 10 kilometer circle, you’re making sure that any poultry premise in that area will be screened, or surveilled, making sure that there’s no positive virus around in the area because of the fact that you’re at a higher risk, right? And then with all of that going on, after all the steps are done, and everything is going on, the yellow boxes that I highlighted here, everything else is going on the rest of the world, right? So, in all—order for these to happen, you want to make sure the diagnostic tests are run. So, all these yellow boxes annotate places where a test is ordered to be confirmed at a laboratory to make sure if there’s a positive or negative status that’s known for each of these poultry premises that are in the control zone or at the infected site, etc.

So, that’s kind of how the outbreak unfolds. David already touched on this a little bit, but the reason why these testing is so important, and I’m harping on it, I’m a—I’m working at a diagnostic lab myself. So, he had mentioned about the reference laboratory, which is actually conveniently in Ames, Iowa, where I am right now. I’m also part of a level one laboratory, and I’ll talk about the levels of laboratories. So, it goes from level 1, which has the largest testing capacity with the biosafety levels, and then we’re fully accredited laboratories. All the way down to level three laboratories, where you see in the green dots, these are laboratories that can do only surveillance testing. So, as you see in this map, and I don’t know where you are geographically, but let’s say if you have a avian influenza diagnosis somewhere out West, in some of these remote areas, you have to make sure these samples are delivered to a laboratory that can test for the virus. So, some of the things that been talked about politically are the reauthorization of the Farm Bill, and this appropriation to make sure these laboratories are running smoothly is part of the reason that the re-authorization is very important. We have to make sure that when there is a detection of the virus, these processes run smoothly so these laboratories can function to make sure that the outbreak control gets started with early detection of the virus.

And as far as some of the moving forward, what are some thoughts to think about? I know there’s a lot of discussion about vaccines. And before I say yay or nay on what the stance is, there’s three critical issues to think about. Number one is the logistics of developing a new vaccine. David had already mentioned about the fact that, just like COVID, avian influenza is a virus that keeps changing. So, back in 2015, we had a different virus. And it also was an H5 virus, but it’s a different H5 virus. That vaccine no longer works for this virus in 2022. So, you have to make sure that the new vaccine will protect against this current virus and hope that it doesn’t mutate or change so that this vaccine that’s produced will continue to be protective. Number two, we also touched on surveillance as well too. Once you start a vaccination program, you have to make sure that you can still detect birds that are infected rather than vaccinated. So, that means a lot of the birds that vaccinated may be masking some of the clinical signs. And think about back when we had the COVID era. Right, people, some people who were vaccinated still were positive or were able to be infected by COVID, but they weren’t showing as strong clinical signs as people who weren’t vaccinated. So, that aspect kind of plays into it as well. And finally, there’s some trade implications and political aspects, where if the United States decides to vaccinate, there are some countries that say, “Well, I’m not really sure if we’re amendable to receiving products from the United States.” So, there’s some aspects that come up with this that you have to consider. Some other points of consideration—and I talked about a little bit—is that, number one: the vaccine is not a silver bullet. This is not going to prevent infection of the birds, right? So, in order to have an exit strategy as the country, you would have to make sure that if you vaccinate, but if you still have positive birds, you have to be able to make sure that you can stamp out the virus. Otherwise, we’ll never be looking at eradicating the virus from the United States. Number two, we haven’t talked about the logistics of vaccination. Think about the COVID vaccine combo. It’s a one shot followed by a second shot a couple of weeks later. That’s typically the standard protocol that we’re looking into with some of the research that’s done by USDA. So, if you think about a two-shot vaccine, in a poultry industry, and, in Iowa, most of my industry is commercial laying hens. There’s 300,000,000 birds, right? So, talk about 300,000,000 times 2, and I haven’t even talked about the 9.6 billion broiler industry or the meat bird industry. So, we have to make sure that we can mass mobilize vaccines available for these birds quickly and efficiently to make sure that all the birds are protected. So, there’s a lot of logistics to think about.

Finally, let’s talk about the economic impact of the virus. So, in 2015 when we had this virus, there were 50 and 1/2 million birds that were depopulated. This is a $1.6 billion direct impact on the economy with additional, you know, numerous factors that go into an economic impact otherwise. In this current outbreak, there’s—it’s actually surpassed the number of birds that were depopulated domestically. However, the amount of money that we spent in order to control this virus thus far is actually less than 50% of the cost in 2015. And this is a testament to the biosecurity practices that the farmers and producers have implemented and also all the research that’s been done to look at mitigation and control strategies, as well as early detection and controlling or biocontainment of the virus. And that’s all I have.


What is being done well in press coverage of these issues, and where is there room for improvement?


RICK WEISS: That’s a fascinating story and real positive story in some ways about how much better we seem to be now on biosecurity. But those wild birds make it pretty difficult, so super complicated epidemic or outbreak to deal with. This has been a fantastic intro. I usually start these briefings with one quick question to all of you, and I want to do that now just for maybe quick answers so we’ll still have time for reporter queries. But just to get started and to help out the reporters covering this beat, if each of you could just say something about one thing you think either from your reading of the press, the media is either doing well or could do better on with regard to how they’re covering this problem. And I’ll start with you, David.


DAVID SWAYNE: I’d say the great thing is the sincerity of which reporters pursue this issue and trying to find out the facts. I think sometimes those facts get mixed up a little bit. And that’s probably the problem with us as scientists and veterinarians in that we don’t communicate very well the specific facts, and they’re easily confused because the issue about avian influenza is a very complex issue. It’s very easy to get lost in the information and get it incorrect.


RICK WEISS: Thanks, Nichola?


NICHOLA HILL: Yeah, thanks, Rick. I think so far the coverage has been responsive and timely. As someone who investigates wild animals specifically, I think the question usually comes back to what is the pandemic potential? And I think that that’s a fair question. But for me, the call to action or a motivation enough to try and mobilize and control the virus is that we are currently seeing a panzootic in wild animals, which means we’ve got a globally distributed virus in a wild reservoir. That’s substantial, and it’s bringing a lot of species to the brink. And so, for me, that’s—I would love to see more coverage of the conservation and biodiversity implications of the—this current outbreak as well as just the economic and the human and public health toll too.


RICK WEISS: Okay. And Dr. Sato?


YUKO SATO: My thing is that I started my job in 2015. So, I started with high path AI last time around, and considering the interviews back then and the interviews in 2022, I really have been impressed with the amount of information that the reporters come with. They’re very well-educated, very well read on the topic, so we’re kind of having a conversation. And I’m just very impressed with the amount of information they already know. I think some areas that may be improved is some of the questions that get directed is like what do you think is going to happen, right? And what do you predict is going to happen? And unless any of us maybe—perhaps the closest is maybe Nichola has a magic glass ball to look into the future, it’s really hard to answer that question as a scientist because we’re looking at data, right, to make an analysis. So, we can call some—for some predictions, but it’s really hard to say what’s going to happen next, right?

How close is bird flu to causing a human outbreak and should the U.S. start preparing now?


RICK WEISS: So, that’s a perfect segue to the first question I’m going to ask you, which exactly breaks that desire of yours, but it’s inescapable that reporters are going to want to hope that at least, as scientists, you might have some clues from mutation rates or other indicators, where things are going. So, to the extent you’re able to address this, we do have a question from Caitlin Tilley, who’s a U.S. health reporter at the Daily Mail. And she’s asking how close is bird flu to causing a human outbreak? Is there a way to tell whether those mutations are getting close to something we should worry about with people? And should the U.S. start getting prepared now for that possibility?


NICHOLA HILL: Yeah, I can take the front end of that question. So, the risk is still low for a human pandemic based on the evolution of the virus that we’ve seen. So, these mammalian adaptations or the mammalian outbreaks that we’ve seen, we’ve only ever seen de novo mutations in what’s called the PD2 gene segment, and this relates to how the virus replicates inside the host cell. We haven’t seen any mutations of—that indicate mammalian adaptation in any of the other gene segments, particularly nothing that we’ve seen so far in the hemagglutinin, and that’s the really important one, as David was saying, because that can define how well the virus is binding to the host cell. And so, we’re seeing just ground floor mutations or evolution of the virus, but not the significant usually in the zone of three or upwards to five mutations that we need to see across different—of the different gene segments, and there are 8 gene segments total. So, we haven’t seen anything that’s bringing it close to crossing over and being a human pandemic at this stage. And I think that’s true of absolutely worth keeping an eye on all of these mammalian spillovers and what mutations that we’re seeing, but, to date, no, it’s considered low risk.


RICK WEISS: David or Yuko? Yeah.


DAVID SWAYNE: Yeah, just to add what Nichola was saying is that if you look at what’s going on, there’s a lot going on behind the scenes that most citizens don’t realize. But when this virus emerged in 1996, there were actually human cases in 1997 in Hong Kong, and that was a wake-up call for public health in that, hey, we need to prepare for possible pandemic. So, in the U.S., there has been massive investment in public health departments and agencies within states to try to increase the outreach into communities and the research institutions to develop a pre-pandemic vaccine strain. So, currently, it’s a global effort through the World Health Organization [inaudible] and we have multiple vaccine strains that are already made ready to be used if this virus turns to be a pandemic. And so, it’s great to see that this is not something that just happened today or yesterday, but it’s been going on for 20 years is this investment to protect us as humans.


YUKO SATO: Yeah, I echo both of y’all’s sentiment. And again, the phrase I like to use is the time for planning is done when the emergency is already here, right? So, when things like this happen, as David alluded to, a lot of the preparation is already ongoing. And recently, the CDC just published a kind of a avian influenza update page. And they talked about this current public health risk being low, which goes along with what all the data has been pointing to. So, again, hang tight. Hopefully, nothing bad happens and, again, we’ll look at and see what the science tells us.


NICHOLA HILL: It might be worth just adding on to that, that I think the human infections that we’ve seen, and just to clarify, haven’t ever been from a wild reservoir directly to a human. So, when those transmissions into human populations happen, it’s usually handling poultry that is the biggest risk factor. And I think—and the others might be able to chime in—I think that’s usually the case. When we’ve done tracing of those cases, it’s usually there’s some kind of poultry handling that has happened. So, in terms of the wild reservoir low, but mix poultry into that equation, and the risk factor changes somewhat.


DAVID SWAYNE: Yeah, that risk has been very low, as Nichola has said, and even historically it’s been low. I think for the H5, there have been 874 human cases, and that’s since 1997. And although each case is critical and important, when you look at the number of exposures, and most of the exposures based on the studies by epidemiologists have been people exposed through the live poultry market systems of Asia and Egypt, where refrigeration is not always predictable. So, you actually go to a shop where they have live poultry and that—and you pick out the birds you want, and they are then slaughtered in front of you, and you take it home. And that process of slaughtering generates aerosols, and that’s where most people are probably exposed. But even though there are hundreds of millions of these processes going on in a year, there have been a very limited number of human cases.


YUKO SATO: And one thing I’ll add is a lot of misconception that’s probably out there is the term high path seems daunting, but it’s highly pathogenic to chickens, not to people, so just keep that in mind. When you see high path avian influenza, it’s a—to a chicken, not to people.


RICK WEISS: Okay. I mean, does that mean that the people who have been infected have mostly been surviving and doing okay?


DAVID SWAYNE: It’s about 40% have been fatal cases, and some of those cases—and this would be a great future opportunity for you to have somebody on your—1 of your shows. That’s a human health expert. But my understanding is that many of those people, the factors that could be secondary factors that increase the susceptibility may be there, and so it’s not just the virus by itself in many of those. Some of it is.

How concerning is it for humans that the strain is successful in marine mammals?


RICK WEISS: Great. And good to remember, we do have bird experts on today. So, thanks for stretching into those realms. Here’s a question from Andrew Lewis from Yale Environment 360. I’m interested in marine mammal transmission. Is the Peru outbreak among seals the largest detected so far? And can the virus be spread from seal to seal, or is contraction only via waterborne transmission from things like bird droppings? Also, how concerning is it for humans that the strain is successful in mammals?


NICHOLA HILL: Yeah, I think all eyes are on that Peru and other South American outbreaks that are going on right now, especially in marine mammals, and those sea lions, the 3,500, is certainly the biggest outbreak in the Americas. And it’s probably up there globally as well. And so, that’s incredibly concerning. And I think the first question to know is, is that mammal-to-mammal transmission, or is that waterborne transmission? And I think when we look at the genetics of the virus, it’s not telling us that we have achieved mammal-to-mammal transmission yet. And so, the most parsimonious or straightforward explanation is that this was a shared water source. So, virions in the water, coastal environments are very dynamic. And so, currents can blow in virion particles into protected areas where seals are holing out or other marine mammals, and they can become infected that way. So, that seems to be the prevailing hypothesis with regard to the size and scale of that sea lion outbreak for sure. Yeah.


DAVID SWAYNE: And it continues to emphasize why we do surveillance is in the case of the mammal cases, and as Nichola mentioned, this 3,500 in sea lions is a really critical number. And that’s the population that we want to do surveillance in to see is the virus changing in that population to get closer to being a virus adapted to mammals and then potentially adapted to humans? And as she has said, so far, it hasn’t shown that, but that’s why we do surveillance is to keep track of that as an early warning to us to take additional action.


NICHOLA HILL: Completely. And I should say that the cases, the samples, from that we—I think everyone was waiting for those sequences to hit, and we just need more sequences in real time to really evaluate that, and wild animals are difficult to sample, slightly different from humans and poultry. So, it really requires logistics and effort to do it. So, it’s absolutely a call to action to try and figure out how we can better evaluate what’s going on in this wild reservoir, for sure.

Is it possible to eliminate a virus like bird flu in the U.S., given the country’s wild animal reservoir?


RICK WEISS: Great. We have a lot of questions suddenly pouring in, so I’m going to try to blow through a lot of them here. And if you can give your concisest answers to some of these, we’ll get to as many as we can. Is it possible—this is from Meg Wingerter at The Denver Post—is it possible to eliminate a virus like this from the country given the wild animal reservoir? Nichola, you—it looks like you’re saying no.


NICHOLA HILL: I mean, I pondered this a lot. I mean, this is the—this is the question that keeps me up at night. I think it’s, as Dr. Sato was saying, that biosecurity in poultry has improved a lot since the last outbreak. And so, the rest of that equation, or the risk factor, comes down to the wild reservoir, and we have very few options for controlling it once it’s in a wild reservoir. We get large-scale geographic spread thanks to the mass migration of birds, and it becomes a whole different consideration for how to control it. Certainly, I don’t think eradication. I think control might be on the table. But I think we just have to wait and see whether we see any evidence of co-evolution between birds and we start to see resistant phenotypes in birds and how quickly that will occur. And that that might be a part of what we witness going forward, but I think it’s incredibly difficult. But I will say that monitoring and surveillance in wild birds is also really predictive, so we do understand now, thanks to largely the boating community reporting where they see birds, and these migration patterns. And I think that information can really be harnessed for predicting where the virus will go and what species are being infected. So, it’s—I don’t think we should consider that we’re helpless to do anything. I think there’s a lot of incredible information that you can harness and utilize and put together to at least start to consider how we’re going to control or eradicate this in poultry and certainly to minimize the human potential for spillover as well.

How much of the current outbreak is found in free range birds?


RICK WEISS: Great, I want to ask our experts, right now in front of everyone, if any of you or all of you have an extra 10 minutes to tack on to this briefing if we need it for extra questions. We have a lot of questions. Fantastic. Let’s try to stretch this a little bit and get everyone’s questions done. Here’s a question from Dave Brooks from the Concord Monitor in New Hampshire. How much of the current outbreaks are in free range birds? Yuko, this might be for you. They seem more vulnerable than birds kept entirely indoors. Are there recommendations to take free range birds into housing in some areas?


YUKO SATO: Thank you very much for that question. We actually don’t have a breakdown of what type of bird facilities there are. We still have like the broader like commercial layers versus broilers, which is the meat type birds versus turkeys, ducks, and stuff like that. But we actually don’t have the premise side broken down on each of the facilities. If you look at the USDA APHIS website, it kind of breaks down on the type of facility you can maybe get a little bit of prediction because you’re not going to have a like 1,000,000 bird free range facility by logistically speaking. But again, the risk is higher, obviously, because they are exposed to potential sources of the infection. But again, it comes down to what biosecurity practices whether that logistically works for these facilities that will be protective for these facilities and the poultry producers.




DAVID SWAYNE: And, just to tack on to what Yuko was saying, so there are provisions on the USDA organic that if they’re high path AI in your area in wild birds that you can keep those birds indoors for a period of time while that risk is high. And then when the risk declines, for example, if they’re migratory waterfowl, if they move in, bring them in, bring your birds inside. When they move out, then you can take your birds back outside. So, those are provisions that are allowable there to maintain the safety of the birds by bringing them in for a period of time.

What steps can small farmers and ranchers do to mitigate the risk of an outbreak?


RICK WEISS: That’s very relevant to another question we have here from Enrico Villamaino from Lee Newspapers. What steps can small or local farmers and ranchers who are largely isolated and have limited resources do to mitigate their risk of an outbreak on their ag operations?


YUKO SATO: I can start, and maybe both of you can chime in a little bit. I mean, first thing is just to be informed, right? So, if you’re—if you’re a small producer, have some sort of credible resource that you can reach out to. What sort of outbreaks or infections have been around in your area? That’s kind of giving you a little bit of an alert. And having these sensible biosecurity practices. So, you don’t have to be in a silver fortress like protecting from everything that potentially could be harmful, but just little things like, oh, did I—did I go to a poultry show? Am I showering and changing my clothes before I handled my poultry? Or am I close to anything that potentially—Let’s say there’s a pond or some sort of water source that ducks and geese can hang out with. Are those close to my poultry? Like little things here and there that makes sense, that’s practical, are probably the best ways to keep these producers from getting birds infected with high path.


DAVID SWAYNE: One of Dr. Sato’s slides had a program that USDA Animal and Plant Health Inspection Service has called Defend the [Flock]. And that’s a good website to go to, to get basic information about how, as a small flock owner, how do you—how do you provide biosecurity to reduce the risk not only have high path AI, but other diseases?

How much of a threat does the bird flu pose to pets?


RICK WEISS: Great. Okay. Let’s see. We have a question from Elizabeth Rembert from Harvest Public Media asking, from Nebraska, where three cats have died of bird flu. How much of a threat does the flu pose to pets? And how should people protect their pets or look for signs?


NICHOLA HILL: So, yeah, so this is a tricky one. And I think maybe we were waiting for this moment to happen. So, there have been documented cases in domestic cats and domestic dogs now that have been linked to predating on dead birds, as tends to be the habit of dogs and cats. They’re predators, too. And so, we knew that this moment would arrive where pets would become infected with high path H5N1. And so far, it seems to be isolated cases. But this is a real call to action for me as well that we’re seeing these so close to home. And so, that’s really worth monitoring. I think the advice that I give is, if you’re walking your dog, keep them on a leash. So, we should always, always—and outbreak on no—be trying to keep domestic animals away from wildlife. And I think that that just is a philosophy that we should take to many aspects of life. And so, just keeping—I have an indoor cat. I love cats, but I also love birds. And so, I just keep them in different spaces. And so, I think that’s really one of the best solutions and easiest that we can come up with. The others might have more thoughts.


DAVID SWAYNE: Covered it well.

What do total depopulation numbers look like globally, and about how quickly do flocks bounce back after depopulation?


RICK WEISS: Okay. Laura Reiley from The Washington Post is asking, “Can you give any data on total depopulation numbers globally at this point from this outbreak? And curious about how quickly after significant depopulation event do flocks come back?”


YUKO SATO: I don’t have that total global default number. Do you have some, David, or?


DAVID SWAYNE: Yeah, since July of 2020, it’s 254,000,000 poultry have been populated or have died. The fact that the mortality rate is around about 31,000,000 have died and then with the depopulation of 254,000,000.


RICK WEISS: Right, and my understanding, David—correct me if I’m wrong for reporters—is that when you look at those government websites, and it talks about birds affected, that means birds dead either from the disease itself or from a depopulation effort?


DAVID SWAYNE: That is correct, and you can go to the World Organization for Animal Health, and that’s the global organization that has 190 countries that are members, and they report this to that organization. They compile the information that is assimilated and available for public domain.

Are there any vaccination pilot projects happening on commercial farms in the U.S.?


RICK WEISS: A few more questions here, one here from France Beaudoin from Radio-Canada Television. Are there any vaccination pilot projects ongoing in commercial farms in the U.S.?


DAVID SWAYNE: So, currently there are not vaccine trials going on, on farms, but there are vaccine trials going on in research laboratories. So, the U.S. Department of Agriculture has their Avian Influenza Research Lab in Athens, Georgia. That’s the Southeast Poultry Research Lab of the U.S. National Poultry Resource Center. And they have vaccine studies going on, as we speak, looking at the vaccines that Dr. Sato mentioned earlier, the 2015 vaccines plus some additional new vaccines that are under research to see if they are protective and could potentially be used in the future.


YUKO SATO: Rick, if I may back up, there was a question about how fast do the flocks bounce back from depop? I was—I was trying to feverishly look for the data. There was a presentation that was done looking at the average time from depopulation to restock approval. Usually, back in 2015, it was about 140 days. And this data kind of stops around October, but the—on average, it’s been somewhere between 20 to 140 days. So, on average, about 70 days for a flock to get the restock approval.


RICK WEISS: And those are U.S. data?


YUKO SATO: USDA, yes, U.S. data.

Is there evidence for airborne transmission of avian flu?


RICK WEISS: Right. Got it. Thank you. Tom Cullen, at the Storm Lake Times Pilot in Iowa. Epidemiologist Michael Osterholm has argued that APHIS and the poultry industry have failed to recognize that avian influenza is spreading through the air. Can anyone comment on that? Michael, someone who’s always been on the forefront of concern about epidemiology. Is there strong evidence for airborne transmission?


DAVID SWAYNE: I’ll take a little crack at that. So, there is some limited evidence of airborne transmission. And that transmission is generally proportional to how close say two barns are together. So, on the same premise, then airborne transmission appears to be a high—a higher risk or a higher probability occurrence. The farther you get away, say, farm to farm, the farther you get the farms apart from each other, it reduces the odds for you having an airborne transmission. And then moving [inaudible] by human activity is a greater chance. Dr. Sato made a couple of comments earlier that are other types of issues that could increase potential airborne transmission. So, for example, if you have wild birds around your operation, and those are on water sources, like a pond right next to your house, then the movement of those birds landing and taking off does—do create aerosols, and those could possibly be, depending how close they are, a source. But I think when you look at all the overwhelming evidence, I think we still have to say that human activity that’s carrying the material on shoes, clothes, and equipment, is higher risk and more likely the choice way that virus gets in and begins those infection processes.


YUKO SATO: Yeah, I agree with David. There’s some preliminary data analysis that’s looking at kind of weather variables as well, too. This was done in 2015, as well, too, but they were looking at if the average wind speed is higher than X amount, the likelihood of contracting virus, and some of that data is starting to get generated. But again, it’s not—it’s not apples to apples here. And so, it’s a—there’s a lot of variables that come with it. One—a very easy example is what David mentioned is the close proximity to an infected site. If you have a farm downwind to this, is that wind, or is that dust carrying the virus? There’s so many other variables that could contribute to it, leading to something not A to B.


DAVID SWAYNE: Yeah, 2015, there was an epidemiologic study done by USDA, and it found that farms in the Midwest that were located adjacent to cornfields, and if they plowed those fields in a close timeline of when the wild birds came through the waterfowl, that was an increased risk factor of farms breaking adjacent to those large fields. So, that’s one example where it could be airborne transmission. Also, there was a recent study just posted on Bio Archive from the UK, and they came to that same conclusion that there may be some airborne transmission. When they look all of the data, it suggested that that is not the primary way the virus moves into farms, into barns, and causes infections.


YUKO SATO: Maybe a backwards way of thinking about it, as I kind of did summarize from the epi data that most of—less than 15% of this times outbreak is farm-to-farm spreads. So, if the hypothesis is that most of the virus is spread by airborne transmission, it will be a farm-to-farm transmission, presumably, right? So, if you’re looking at that percentage, I—perhaps some of that is due to airborne transmission, but it’s a lot less likelihood considering the majority of them are point introductions from migratory waterfowl contact.

Is there any concern that wild-bird repopulation efforts could be introducing the disease into new areas?


RICK WEISS: That’s a really interesting way of looking at it. Seems like reduces that likelihood of serious airborne transmission being a big part of the problem. We’re going to get one or two more questions in, in our last five minutes here. This is from Laura Lundquist at the Missoula Current. Wildlife biologists transplant birds such as grouse into different areas for recovery programs. Is there any concern that that could be introducing disease into some areas that might not otherwise have it? And would testing be necessary or good idea to prevent that?


NICHOLA HILL: That is an interesting question. So, I think it can’t hurt to step up testing, especially when relocation efforts are happening of wild populations. Do testing before and having a quarantine phase and testing after introduction and monitoring. I will also say that grouse and a lot of these landbirds or game are probably lower risk. So, what we notice is waterfowl and aquatic birds tend to be birds that are susceptible and can replicate and move the virus. But what we haven’t really seen is infections in backyard birds, so passerine, songbirds, land birds, and that’s despite the huge birding communities across North America. So, these are one of the most intensively monitored populations, our backyard birds, and we just haven’t seen the data to suggest that it’s moving or is successful or efficiently spreading in those populations. So, I think there are phylogenetic constraints here, which we can sort of take a sigh of relief and say if it really is about species that are mostly related to waterfowl or share aquatic habitat with waterfowl, that tends to be at highest risk, but grouse that are moving, there was another question about what birds are on the brink? And could I name some of them? I think, yes. We—bald eagles are once almost vanished from the North American landscape, and they’re having—they’re a big comeback story. And so, I think this is a species where avian influenza has really hard hit them. And so, a lot of those conservation efforts have taken some steps back because of the—this infection of the virus. We also have northern gannets along the North Atlantic. We have birds that are at a scale of local population or regional scale that are right on the brink of extinction. We have common tern, sandwich tern, populations were completely—were close to brought to the brink of their populations. So, I think for seabirds and shorebirds that are already very much so on the brink, this could be like another factor that spells decline for seabirds and shorebirds especially that are not doing well. And there a handful of other cases of this happening too in other landbirds species where we’re trying to get these populations on the—on the upswing, and this virus is just setting us back, and that’s really unfortunate.

What would have to happen to increase the risk of bird flu spreading to humans?


RICK WEISS: We’re just about our last question here. I want to come full circle, even though there might be some resistance to this to talk about humans a little bit more because it does of course remain of great interest here. And this is a question that sort of compiles that concern from Felice Freyer at The Boston Globe. Risk to humans you’ve mentioned is low now. But what exactly would have to happen to increase that risk? And in what scenarios could avian influenza mutate to something people can catch and spread to others? Is the key the movement into other mammals or are there other routes that we should be thinking about here?


YUKO SATO: I’m going to default to David here, but I can start very broadly. The risk of mutation is basically the—2 different types of viruses have to affect the same cell. So, if there’s more circulating virus around, the likelihood of mutation is higher. That’s what I’ll start with. And then I’ll pass it on to David.


DAVID SWAYNE: Yeah, this is a tough question because to say what does it take for this virus to be human-to-human transmissible? We know a little bit from experiments in other mammals that would tell us if you have a particular mutation in one gene, it increases the chances of transmission, but it does not meet the full definition of a—of a virus that’s easily transmitted human to human. So, there’s got to be more science done, more understanding of what accumulative changes—and that’s multiple mutations—would make that happen. I think one of the kind of, I think, sort of issues that kind of helps me sleep at night is that this virus emerged in 1996. And we’ve seen human cases since 1997. And it’s been watched very closely by public health agencies around the globe. And to this point, this virus has not passed a threshold of this transmissible in humans to humans. And it’s despite 20 years of watching, it hasn’t happened. So, that’s kind of reassuring. It doesn’t mean it wouldn’t happen. But it means there is somebody out there looking that understands the public health implications and ramifications, and they’re monitoring the viruses. We’re monitoring the agricultural setting, Nichola and her colleagues in the wildlife setting. And in the human side, the same thing there. And so, that’s—that information is presented usually on pretty close to real time and analyzed genetically and pathologically to see is that virus moving? And so far, that’s been reassuring is not.

What is one key take-home message for reporters covering this topic?


RICK WEISS: Great. Well, we are about out of time. And I appreciate everyone adding some extra minutes onto this very hotly watched briefing. I’m going to wrap up here with one last question to each of you. But I want to remind reporters, as you get ready to log off, you will get a short survey popping up on your screen as you leave. It’s so helpful. If you take the 1/2 a minute, literally, that it’ll take to answer three quick questions, it’ll help us continue to make these briefings as useful to you as possible. And I’m going to go around the horn for just a quick half a minute each here, for each of you, to just tell reporters one last take-home. If there’s one thing out of everything we’ve been talking about today that you want them to walk away with and remember, what would that be? And, David, I’ll start with you.


DAVID SWAYNE: I’ll have two take-home messages. One is that the farmers in the U.S. take their production systems very seriously. And in the United States, we have 294,000 poultry farms. And when you look at that, we’ve only had 230—323 farms break with high path AI. I think that says that the farmers are serious about this. They’re doing their best in biosecurity to keep this virus out of their farms and therefore keeping our food supply safe for everyone. The second point I want to—for you to understand is that we are privileged to live in the United States where we do have such a strong food security and food safety culture. I think around the world, we’re seeing this virus moving into low income countries, and this has having a huge ramification on their poultry populations, both smallholder and as well as commercial. And this has created a food security issue in many countries, especially in egg production, where, in many countries, the egg is the primary high quality protein source for human nutrition.


RICK WEISS: Interesting. Okay, Nichola?


NICHOLA HILL: Yeah, in terms of a takeaway message, I think that we are sort of faced with all of the—these facts and data about the magnitude and frequency of these outbreaks and that it’s now a panzootic in animals, and I think people maybe shouldn’t feel helpless. This is probably worth—and this is a long-term and more meaty solution, but it’s probably worth a rethink about food production, period. And I think that’s really the elephant in the room is that not, I mean, I think we have to think about how food is produced in the scale and whether these conditions start to create—are more favorable to viruses to spread and gain virulence. When it spills back into wild bird populations, it’s met with wild birds, which have—are more heterogeneous, and so they’ll develop their own resistance mechanisms, or they’ll just die. But with poultry, I think we have more that we can do. And so, I think there’s some discussion that should be had about the scale and industrialization of food production in the U.S. and worldwide that should probably be part of the solution.


RICK WEISS: Okay, well, you’ve opened up a big barn door of things we can talk about in another briefing there, so thank you for that. And Dr. Sato, over to you to wrap up.


YUKO SATO: Yeah, I’m going to mostly echo what David had said. One is these farmers are—there’s always room for improvement on biosecurity, but they’ve made some significant inputs, and that’s now part of their new normal. So, I want you to understand that this is their livelihood to care for the animal wellbeing because, at the end of the day, they want a product that market, right, whether that’s meat or egg products. And the fact—number two is that I talked about the outbreak control methods, and it starts with detection. So, rest assured any infected product would never ever enter the food chain. So, and even if it did, this virus is very wimpy, as David described. So, poultry products, in general, are safe to eat, so nothing to worry about with influenza. Carry on. Eat your eggs and chickens.


RICK WEISS: Great point, hadn’t come up. Thank you for that. I want to thank our panelists today for a spectacularly informative, interesting discussion on an amazing dynamic that’s going on in this interface of nature and our economy here. It’s been a fascinating hour plus. Thank you so much. Thanks to the reporters for attending and for doing the work you do to inform your audiences about issues like this. We look forward to seeing you at the next SciLine media briefing. So long.

Dr. Nichola Hill

University of Massachusetts Boston

Dr. Nichola Hill is a biologist who studies how viruses emerge from animals in an increasingly human-altered world. She is an assistant professor at the University of Massachusetts. Her work on avian influenza and SARS-CoV-2 takes an ecological and evolutionary approach to understanding the conditions that create a tipping point for outbreaks. Dr. Hill performs field research in North America and understudied parts of the world, including Mongolia, Egypt, Bangladesh, Zambia and Alaska to characterize the the growing interface between animals and humans.

Declared interests:


Dr. Yuko Sato

Iowa State University

Dr. Yuko Sato is the poultry extension veterinarian and diagnostic pathologist at Iowa State University and is a diplomate of the American College of Poultry Veterinarians. Her extension programs focus on poultry infectious disease diagnosis, prevention, and investigation. Dr. Sato is very active in scientific organizations such as the American Association of Avian Pathologists and United States American Health Association.

Declared interests:


Dr. David Swayne

Poultry veterinarian

Dr. David E. Swayne is a private veterinarian with specialization as a veterinary pathologist and poultry veterinarian. He has lectured and published extensively on the pathobiology and control of poultry diseases, primarily avian influenza, and he has edited both textbooks and professional journals. Dr. Swayne serves in leadership roles at the World Organization for Animal Health, where he has led critical updates to the avian influenza chapters in international veterinary guidelines.

Declared interests:


Dr. Nichola Hill slides


Dr. Yuko Sato slides


Dr. David Swayne slides