Over the past year, a particular strain of the flu has been making headlines around the world.
Some types of bird flu exists harmlessly in wild birds, but a new, highly contagious strain is fatal to chickens and it's spreading around the US. New reports from January document millions of infected birds in nearly every state.
Despite its name, this bird flu has not stayed in birds. It's known as H five N one, and in the US alone, it's been found in bobcats, bears, dolphins, foxes, skunks, and otters. And as the list of infected mammals keeps growing, humans are getting nervous because bird flu sometimes does make its way to people, and when that happens, it can be deadly. So today we're going to try to understand where the flu comes from, how it jumps from species
to species, and what this all means for humans. Also, we'll hear an account from the front lines of influence of research, And by front lines, I mean a little island in the North Atlantic that's full of seals.
You've got a bunch of scientists all geared up in our field gear and we are crawling through army crawl style through the dunes to sneak up on a seal pup. It can be somewhat comical if you didn't know what was going on.
I'm Jacob Goldstein. This is incubation. Okay, you ready, Let's talk about viruses.
Okay, let's talk about viruses.
For today's episode, I called up David Kwalman. He's a journalist who writes about ecology and evolutionary biology, and he wrote a book called Spillover Animal Infections and the Next Human Pandemic. David has spent years tracking viruses like the flu across animal species and he's documented their spillover into the human world. I'd like to talk about when people figured out that flu was a disease of birds.
Yes, there is a wonderful eminent influenza scientist and physician named Rob Webster, originally a New Zealander who has been at Saint Jude's Memorial Children's Hospital for most of his career studying influenza, and back in the nineteen sixties I think it was nineteen sixty seven, he and a friend of his were walking along a beach in Australia and they found a bunch of dead birds lying on the beach. Shearwaters.
What killed all these birds all of a sudden. Well then they wondered whether, I don't know, could it have been maybe an influenza. Maybe we should do a little research on that. So they went to their boss and they said, we want to go to the Great Barrier Reef and live on an island for a few weeks and sampled dead birds and any birds that we can
catch and see if we can find influenza. And their boss happened to know that Webster was a passionate sport fisherman, and he looked at these two young guys and he says, you guys are delusional. Webster told me that verbatim. He said, this man looked at them and said, you guys are delusional if you think I'm going to pay for you to go and live on an island off the Great
Barrier Reef and fish. But they persist, and eventually they get a small stipend for the who so they go out there and do this research and they find flu in birds. And from that effort and a lot of research that followed after it. But thanks largely to Rob Webster and his friend, we know now that all of the human influenza A type viruses that infect us come from wild aquatic birds.
Huh. And to ask sort of the dumb question, why is that important? Why is that a big deal?
Well, with any sort of viral threat that's getting into humans periodically, dramatically, murderously, it's important to know how how is that getting into humans, so we can prevent them from getting into us.
So let's talk about H five N one. It's been around for a while.
Right, This version of H five N one has been around since nineteen ninety six. It was found killing some birds, and then in two thousand and five it killed a large number of bar headed geese at a place called Chinghai Lake in western China. From there it has gone from infecting wild birds to infecting domestic birds and then infecting mammals.
I want to just talk for a minute about the influenza virus. It's interesting, right, It's interesting how it works, how it functions. So just like, tell me about the influenza virus.
The influenza viruses belong to a family of RNA viruses, meaning that their genome, the little information molecule inside the protein capsule of the virus, is written in the molecule RNA rather than DNA. DNA is the famous double helix molecule. It's very stable, it has self repairing mechanisms, and so when it copies itself, it corrects its mistakes, doesn't make very many mistakes. When RNA, a single strand of RNA
copies itself, it makes a lot of mistakes. RNA viruses evolve quickly and are capable of jumping from one kind of host into another. The influenza viruses also have another trick. They have segmented genomes. So their genomes twelve to fourteen thousand letters of RNA is segmented into eight segments that pop apart between one and the next. So imagine an engine, a locomotive, and six box cars and a caboose, and that's your influenza virus.
So now we have this virus, the flu virus, and the whole genome can change quickly and does change quickly because it's RNA rather than DNA. And on top of that, you have this sort of segmented you know, railcar like nature that allows for kind of rapid change as well.
And that rapid change is accomplished by swapping of pieces with other viruses. If two different particles of influenza replicate themselves in the same cell at the same time, then there is this event, this trick called reassortment that can occur.
And that reassortment is really bad for say, our immune system. Right, and suddenly we've never seen anything like this one before.
That's right, that's right. And so why does a virus get called H five N one? The numbers refer to the fact that there are you know, fifteen or twenty variations of the possible H segment and a number of other possible variations of the end segment. So you have H five N one, H two and nine, and the H and the end.
Are proteins that are on the surface of the virus, right, and so that our immune system record, that's correct. So okay, so we have this virus. It has this ability to change very quickly. How does it go from species to species? We know that it's largely in birds. How does it move among species?
Well, by contact is the first answer to that. That's the ecology side. A wild bird becomes infected with an influenza, let's say a duck, a wild duck. Rob Webster says, the duck is the trojan horse when it comes to bird flu avian influenza.
Like it I like a semi mixed metaphor.
What he means by that is it's the secret carrier. When a duck becomes infected with avian influenza at least many types of avian influenza, it doesn't show symptoms, it doesn't fall down. It continues to migrate and congregate with other birds, carrying the virus and pooping it out into lakes, ponds, streams wherever it goes, depositing this little gift of virus, and other birds then are susceptible to that virus when
they pick it up. And then if your chickens and your geese start to fall dead, you might think about that trojan horse in the form of a duck that came through and brought that virus.
Okay, so now it's gone from bird to bird. How does it go from bird to mammal?
A virus such as influenza gets into animal cells by attaching to particular receptors on the surface of those cells. In birds, it attaches to a particular kind of receptor. Humans have a different kind of receptor. Pigs have both the bird like and the mammalian receptor. So a pig can become infected with a virus that is adapted to attaching to the bird receptor, and then while it's multiplying in the pig, that virus can evolve to be able
to attach also to the mammal type receptor. When it comes out of the pigs, it's capable of infecting humans.
Ah, so it's easy for a pig to get bird flu, and pigs are this sort of mixing vessel basically, where a bird flu can mutate into a flu that can infect other kinds of mammals, including humans. That's right, Okay, So I think now we have a really good base of knowledge to talk about H five N one, this strain of flu that is currently infecting birds. First, tell me the scope of it, like how much is it infecting birds? How many birds is it infecting?
Well, this version of H five N one for the last couple of years has been circling the planet. It's probably killing millions of wild birds. And if and when it gets into those bird species, wildbird species that are endangered, like the hooping crane with nine hundred individuals on the planet, or the California condor with maybe three hundred individuals, it has the potential to knock those out entirely, to drive both of those species over the brink of extinction.
You've described what's happening with age five in one as a kind of pandemic that is happening right now.
Yes, for birds, For wild birds, it's a pandemic, and for domestic birds it's a pandemic. If you have a million chickens on a poultry farm and the bird flu comes in by way of a duck that happens to come and poop in their water trough and some of those chickens get infected, that virus can spread through those million chickens very quickly, which means billions and billions and
trillions and trillions of viral particles replicating. Each time the virus replicates itself, there's a potential for it to make mistakes, to have a mutation, a random mutation, and several of those random mutations can create a virus that can infect the guy who's cleaning out the cages. So the fact that we have thirty three billion chickens on this planet at a given moment means that there is this huge petri dish for the encouragement of evolution in the bird
flu virus. Millions of birds in poultry operations around the world have either died or been killed preventively to stop the spread of this this virus in commercial operations.
And infections of people have been thankfully rare so far, Yes, they have been rare. Right And crucially, there's no evidence that it can go from person to person. It just goes from bird to person when people are working very very closely with birds.
So far, Yes, that is being watched very carefully, although probably not as carefully as it should be watched. There is such a randomness, such an element of randomness involved in influenza evolution, that you can know what its capacity to evolve quickly is, but you can't say what's going to happen tomorrow.
Plainly, the terrible day that we hope will not come is when there is demonstrated human to human transmission of H five and one short of that, what should I look out for, like, as a person who wants to be well informed about this, Like, what's the signal that I need to, you know, buy some bottle of water and lock the door.
Well, one of the signals that is increasing in volume is the infection of mammals with H five N one bird flu. So when you see another story about well, bird flu just killed another porpoise, bird flu just killed another dolphin, another seal. That is a warning alarm, and the more it happens, the loud of the alarm gain.
We'll be back with more in just a minute. My guest for the second half of the show is Wendy per Year. She's a molecular virologist at the Coming School of Veterinary Medicine at Tuffts University and her job is looking out for that key warning sign that David Kwaman was talking about. She studies wild mammals to try and detect when they're being infected with H five N one.
It's H five N one two three four four B. It's like it's very it just rolls off the tongue right.
Wendy told me about a moment last spring when she got an alarming phone call. It came from Linda Dohity, who runs an organization called Marine Mammals of Maine.
So she called me as I was pulling into my parking spot and she's like, Wendy, I think we might have a problem. We have some seals that are are coming in. They're showing really strong respiratory signs like I'm really nervous that high path has arrived here in the seals.
High path means high pathogenicity, which means bad flu strains like H five N one.
Honestly, this kind of felt like our mission impossible moment, so I instructed her to overnight samples to me. So she has all of the supplies in house there of the different vials that we need, and it's really it's the same exact stuff that we all have used doing COVID screening, so it's you know, they get swabbed, it goes into a viral transport media into a little tube, but.
From a seal, so they're sticking like a Q tip up the seals nose.
Yes, so we stick Q tips up the seals nose. So we do nasal samples and rectal samples, which thankfully we haven't done with humans. And those all came to me overnight and we immediately ran those samples as soon as they arrived here in the lab, and we detected a really strong signal for the H five N one for the high path influenza.
Whendy ran the tests again just to make sure, and she got the same result. H five N one had made its way to seals along the coast of Maine. She sounded the alarm, notified the FEDS, and fortunately this outbreak passed pretty quickly, but Wendy and other scientists are still worried about future outbreaks. Let's just talk about why this moment is a big deal, Like, why is this such an important moment?
So one of the major reasons is that there's a lot of different forms of influenza that circulate in wildlife, but when it makes that shift into mammals, because it's usually circulating in birds, and when it shifts over into mammals, obviously we're a mammal. So that means it is one step closer to being of concern for human health and pandemic potential.
It's basically it's just getting closer to us in a biological sense exactly.
Yeah, they're all been referred to as a as a sentinel. They're able to give us a heads up of what sort of things might be moving from birds into a mammal, But not to say that the seals themselves aren't. For
it's not just about the human health. So it's also that you know, there is concern that it was going to have a very large impact on wildlife as well, because this is a whole new virus that is going into a species that hasn't seen this virus before, so potentially they don't have the immune protection in place to be able to handle that. So it's human health, it's the animal health, it's all of it.
How do marine mammals get a hive in one this high path flu That.
Is an excellent question and that is one of the things that we are actively still trying to find out. So there are a couple of different ways. It seems pretty clear it's coming from wild birds. So the bird is where the virus is circulating and it spills over and makes its way into seals. So the question is how exactly it could be the case that the seal is actually consuming an infected.
Bird, eating it, yeah, eating it, Yeah.
And that's what we've seen a lot of terrestrial mammals that that seems to be.
How I mean, do seals eat birds well.
In some cases, yes, but it is not It certainly is not a common thing on their their venu and given the number of seals that we saw with high path influenza, it seems very unlikely that each of them were having the unusual meal of a bird, so it is it's the highest probability in my mind, is that the virus is being shed into the environment and that the seals are coming into contact with it, whether it is bird poop on the beach and they're you know, ingesting it or inhaling it that way, or we see
little bodies of water where birds are pooping in the water there and the seals are then hanging out in that water too, So that's certainly possibility.
I mean, it's worth noting that with birds, flu, unlike in humans, is is a fegal oral. It's a like a gas through intestinal right right exactly.
That's an important point. So in birds it's a it's a gi so it's they're they're shedding it in their feces and.
That's how birds spread it to each other like humans get some diseases that way, like from drinking dirty water, and that's the way flu works for birds, but not for people exactly.
Yeah, so it's possible that that's how it's getting into seals as well. Okay, it's also possible that the seals are spreading amongst themselves once it gets into that population, and that's something that is still being very actively looked at. It's not clear yet, it's not really ruled in or ruled out.
I mean, you mentioned that just kind of like as one of several options. But that's a huge, huge, high stakes question for people, right, Like the virus going from birds to seals is way different than the virus going from mammal to mammal. Right, that is a huge, huge, profoundly important public health question. It absolutely is. I'm shocked, frankly that we don't know the answer. Scared, Yeah, I know.
But the thing is is it's not an easy answer to get because you need a pretty sizable data set to really be able to say anything with confidence. And the number of sequences that we were able to get from viruses off of seals is a small enough number that the data is still not clear. It's not really convincing one way or the other.
So, Okay, that's the sort of abstract, high level story. I also want to talk about your field work. As I understand you go out and basically hang out with seals. Tell me about that.
So we have several different sites around the Gulf of Maine. The primary one that I personally go to is Montomoy, and that is off of Cape Cod, Massachusetts.
What part of the year do you go to Montomoy?
The time when everybody wants to go to the islands off of Cape Cod in the middle of the winter January and February. Montamoi is one of my favorite places on the planet. Though it's off of Cape Cod, it's very remote there is there's there are no developments there, there's no heat, electricity, running water. The boats go and drop us off and we have whatever food and water and safety gear we brought with us. And there is an old lighthouse there. It's actually two hundred year old
lighthouse just had its anniversary. It hasn't been operational for the last hundred years. So the Park Service is very gracious in letting us use that as basically a base camp.
And it's you and a few researchers and how many seals.
Oh, lots of seals. So in the region, it's estimated that there's probably about fifty thousand, but on Monomoy we're talking a couple of thousand at that period of time.
That's a lot of seals, A lot of seals. I mean, what's it smell like?
So the very first time that I went out to Monomoy, we're all geared up and we land on the beach and we start to walk over to the seals, and there's this pungent smell of skunk, and I was like, oh, somebody must have been spray I by skunk on there like their field clothes, and we're just none of us are talking about it, so I'm just gonna We're just going to carry on. And then eventually I came to realize that no, no, that muskie smell, that is the
smell of the seals. So it smells very similar to skunk in my opinion.
What do they sound like? Is it loud like you hear like a thousand seals going off.
During the day, Typically not at all unless they're they're kind of bickering and fighting and having some territorial little battles. At night time, it's sort of a consistent, low bellowing that you hear in the background while you're while you're trying to sleep. It's actually quite nice ambient noise.
It does sound a feeling that sounds better than the smell certainly right. So so you're out there, what do you do?
We are going out and actually capturing the pups, and we focus on the pups because they are, give take, about one hundred pounds as opposed to the adults, which can be around eight hundred pounds. So we're able to physically restrain the pups. And that's why we're there during January and February because that's the pupping season. It can be somewhat comical if you didn't know what was going on.
You've got a bunch of scientists all geared up, and we are crawling through army crawl style through the dunes to sneak up on a seal pup and put this bag over the seal that we then capture it, and we're doing sample collections. We're doing measurements to look for just the overall health of the animals, and then we
put a tag on them. In some cases we put on a satellite tag so we can actually follow their movement and then we release them and all of that can happen and as quickly as six minutes, and then we max it out at twenty minutes. So if we hit twenty minutes, we release the seal.
So when you go out in the winter and you are swabbing baby seals, like you are doing the sentinel work, you're like out there looking for H five in one to be the early warning system for the rest of us. Exactly.
We are trying to pick up anything that might be developing the ability to go from birds to mammals and then trying to figure out is that something that then presents the possibility that it could then come into humans or other wild mammals, but mammals in general.
So if I hope not, When let's say, if someone finds a clear instance of H five in one spreading from mammal to mammal, what will that mean?
That is the point where we collectively need to get much more serious about preparing for it. The good news with high path influenza is I like to say, it's not COVID, so it's we see it coming. We know influenza, we have vaccines against influenza. We have seed stocks that are maintained to be able to rapidly grow up vaccines,
so we have the capacity to respond. It's important that we continue to do very robust surveillance so that we know if or when these changes happen, and what exactly they look like.
I will say, after talking to you about what's happening with H five N one and mammals, I'm certainly not not worried, but I am less worried than I was before I talk to you.
Excellent. I like to think that we will be prepared for the human health side of things, that we will be prepared to respond pretty efficiently and pretty rapidly should it become a concern for human health. My bigger concern is for wildlife. That's a much trickier one for us to be able to mitigate, and it could have a very long lasting, very negative impact to several wildlife species. But I think from human health we will be able to hopefully respond well.
I appreciate all your time.
Yeah, absolutely.
One last thing. About a month after we spoke with Wendy, H five N one was detected in seals off the coast of Washington State. It was the first time AGE five and one had been detected in marine mammals off the west coast of the United States. Thanks to my guest today, David Quarman and Wendy per Year. Next week we'll be talking about HPV human peppellomavirus and about how the HPV vaccine explains American's complicated relationship to all vaccines.
The HPV story is so interesting because support was coming from everywhere, but backlash was coming from everywhere too, Like all over the Political Spectrum.
Incubation is a co production of Pushkin Industries and Ruby Studio at iHeartMedia. It's produced by Gabriel Hunter Chang, Ariela Markowitz, and am Gaines McQuaid. Our editors are Julia Barton and Karen Schakerjie Mastering by Anne Pope, fact checking by Joseph Friedman. Our executive producers are Katherine Girardeau and Matt Romano. I'm Jacob Goldstein. Thanks for listening.