Author Interviews
10:45 am
Fri October 12, 2012

The Man Who Tracks Viruses Before They Spread

Originally published on Fri October 12, 2012 12:53 pm

This interview was originally broadcast on Oct. 11, 2011. The Viral Storm will be published in paperback on Oct. 16.

The New Yorker once called virologist Nathan Wolfe "the world's most prominent virus hunter." Wolfe, the director of the Global Viral Forecasting Initiative, spends his days tracking emerging infectious diseases before they turn into deadly pandemics.

In The Viral Storm, Wolfe describes how most of those emerging infectious diseases originally start out in animals before making the jump to us.

"Almost all of them start from an animal virus, an animal microbe that jumps over to humans," says Wolfe. "That's actually the same with most of the major diseases of humanity. These things actually start with animals."

In Central Africa, where Wolfe has worked for over a decade, hundreds of thousands people still hunt and consume tropical wild game, called bush meat. The practice has allowed viruses like HIV to leap from wild animals to humans — and then spread rapidly across populations.

Wolfe and his colleagues in the region stress the health hazards of bush meat. But he tells Fresh Air's Terry Gross that it's difficult to change hunters' behavior without providing alternative sources of protein.

"We're actively working to come up with animal protein solutions," he says. "There are organizations around the world that we're in active discussions with on ways we can introduce novel sources of animal protein that will allow people to have different sources protein so they're not forced to hunt animal game. But most of our mission is to understand what's crossing over [from animals to humans] and to catch it early."

Wolfe regularly receives dried blood samples from animals and hunters in the region. The blood spots are taken to a lab, where they provide a quick map of the viruses that are in each region that can potentially to jump to humans.

"We see new things all the time," he says. "We see new retroviruses out there — which is the category that HIV falls into — and we're very, very concerned because this is the part of the world where HIV jumped from chimpanzees to humans. There's no reason why other viruses in that same class won't have the capacity to leap to humans ... We've found new species of malaria ... and we're really starting to burn through this massive collection of blood spots to determine just what's out there."

Avian Flu

Wolfe also recently traveled to Asia, where the first cases of the H5N1 flu were spotted several years ago. H5N1 has killed hundreds of people around the world since it re-emerged in 2003.

The original strain of H5N1, explains Wolfe, jumped directly from birds to humans. Other viruses, meanwhile, make the leap to domestic animals before infecting humans; that mixing can then introduce deadlier strains of unknown viruses into the world.

"So what happens is you have a particular pig out there and it could get infected with two different viruses — maybe one that's been in human and one that's been in the original reservoir of a bird — and they can mix and match their genes and create mosaic daughter viruses that will have completely novel properties," he says.

That's where things can get particularly deadly. Wolfe says he thinks of viruses as having two dials: one for how transmissible they are and one for how deadly they are. The H1N1 virus, which spread to over 200 countries in 2009 and 2010, is considered to be extremely transmissible — but not extremely deadly. Meanwhile a different strain of bird flu — the H5N1 — is incredibly deadly but didn't spread as effectively as the H1N1 strain. Wolfe's team tracked people who had H1N1, but he says they were more interested in people with the deadlier strain.

"And the reason why was because we were really scared that these H5 and H1 viruses would come together in a particular human or pig and create one [virus] that was off the [transmissible and deadly] dials," he says. "And that's of course the devastating pandemic we're trying to avoid."

He points to HIV, which existed for decades before humans first became aware of it.

"Are we willing to live in a world just waiting for [viruses] to go global before we catch them?" he says. "I think that's one of the things we're trying to change. ... The earlier we detect these things, the more we have the potential to save lives in the future."


Interview Highlights

On the first person thought to have developed the H5N1 avian flu. Patient Zero was a young boy named Captain who lived in a small village in northern Thailand where he helped his grandfather care for their family's chickens.

Wolfe: "That year, a number of chickens had died. And [Captain] wanted to help out with the tasks and he carried some of the sick chickens during the outbreak that they had. A few days later, he came down with quite a severe illness ... and sadly he died. He was the first death that country had from H5N1."

On pandemics increasing in frequency

Wolfe: "If you look now [at air traffic maps] you see basically a plate of spaghetti. There are incredible connections — airlines and boats are moving humans and animals around the globe. The features of globalization have huge consequences on pandemics. It just connects us so much more closely. ... And as a consequence, every one of these viruses that passes from animals to humans has the capacity to infect all of us."

On what lives on your body

Wolfe: "If we were to count the number of cells between the top of your head and the socks on your feet, we would find that 90 percent of those cells are not human cells. Ninety percent of those cells belong to various microorganisms that exist, primarily in your gut and on your skin but also in many, many parts of your body. There's tons and tons of microbes out there."

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

Transcript

TERRY GROSS, HOST:

This is FRESH AIR. I'm Terry Gross. My guest is virus hunter Nathan Wolfe. He's conducted research in viral hotspots like Central Africa, where the HIV virus began spreading. He's studied how viruses like HIV, monkeypox, and the so-called bird flu jump species from animals to people.

He helped discover new viruses that jump species when hunters killed and butchered non-human primates. He's also studied hunters who are exposed to the blood and body fluids of monkeys, bats and wild pigs. Wolfe warns that viruses hitchhike with travelers, so that we should be prepared for viral pandemics that in earlier eras would have been contained in small villages. His goal now is to stop epidemics before they start or contain them once they get going.

He's the founder of the companies Global Viral and Metabiota and is a visiting professor at Stanford. In 2005, Wolfe won the National Institutes of Health Director's Pioneer Award. He's the author of the book "The Viral Storm: The Dawn of a New Pandemic Age." I spoke to him last year when the book was published; it comes out in paperback next week.

Dr. Nathan Wolfe, welcome to FRESH AIR. It's not quite flu season yet, but it is flu shot season, and one of the first stories you tell in your book is about how the H5N1 bird flu began in a village in Thailand. This was a couple of years ago. Would you describe what the first patient was and how he got sick?

DR. NATHAN WOLFE: Yeah, this was a young boy. His name was Captain. He lived in a - just a small village in Northern Thailand, area that I've spent some time in myself. And basically what had happened was he was - he had always been playing with his grandfather, and he had been hanging out with his grandfather. And one of the things that happened that year was that a number of the chickens in the chicken farm that his grandfather had had died.

And just like he would have done anytime, he wanted to help out with the tasks. This was sort of what he did as a young boy. And he carried some of the sick chickens during the outbreak that they had. A few days later, he came down with a - quite a severe illness, and it went back and forth.

Eventually, his father ended up taking a long drive to take him to one of the big city hospitals, and sadly he died. And he was the first real death that that country had from H5N1, which we think of as the bird flu, we know as the bird flu.

GROSS: So he got sick from carrying a sick chicken.

WOLFE: That's right. That's exactly what happens. And if we think about the vast majority of these pandemics that we're experiencing, almost all of them start from an animal virus, an animal microbe that jumps over to humans. And that's actually the same with most of the major diseases of humanity. These things actually start with animals.

GROSS: And you say virtually all human flu viruses originate in birds, even though we don't call all of them bird flus.

WOLFE: That's absolutely the case, and it's sort of one of these - at least for virologists - a fascinating situation, where you have - it's actually interplay of a couple of different animals. So most of the diversity - and we can't say that we know everything about what's out there in nature, but our understanding is that most of the diversity of these flu viruses exist in wild bird populations and particularly some of these migratory waterfowl, things like ducks.

And what happens is those have the potential to jump into humans, as happens with H5N1 directly. They also have the potential to enter into other animals that we have around us, things like pigs. And then one of the fascinating things about these viruses, we think of viruses as sort of asexual, in other words, that they don't sort of mix and match their genes. It's just they enter, and they start spreading, and all of the daughters are exactly identical to the mother.

But that's not the case. So what happens is you have a particular pig out there, it could get infected with two different viruses from maybe one that's been in humans for a while, one that's from the original reservoir of bird. And they can mix and match their genes and create mosaic daughter viruses that will have completely novel properties.

GROSS: And that can be really deadly, like you give an example of two different flus. If they combined, it could really be dangerous. Tell us that example.

WOLFE: Well, I mean, it goes back to, say - now I'm switching gears to H1N1, what people know as the swine flu - again, a bit of a misnomer for those of us who study these things.

But - sorry, just to take one step back, when I think of these viruses, and I watch them spreading around, I sort of, in my mind, envision two little dials. One dial - for some reason, it's always on the right-hand side for me - is how transmissible is a virus, how easy is it to go from one person to another. And on the left is sort of how deadly is it.

And you think about these two viruses, H1N1 swine flu, H5N1 bird flu. So H1N1 - incredibly, incredibly transmissible. I mean, this is a virus that went from infection zero individuals to perhaps 10 percent of the human population within a single year. I mean, this is just viral fireworks, absolutely incredible.

Now, fortunately, nature handed us a virus that wasn't that deadly. On other hand, you look at H5N1, that's a virus that was incredibly deadly, is incredibly deadly, and both of these viruses still exist in humans. And, of course, that one didn't spread around so effectively.

So when H1N1 really started going, interestingly, we were interested in H1N1, but we started focusing really closely on the people who had H5N1, and the reason why - and the areas that had H5N1 - was because we were really scared that there would be a recombinant.

In other words, these H5 and H1 viruses would come together in a particular human or particular pig. They would mix and match their genes and create one that was off the dials on both of them, something that had the potential to spread and was very, very deadly. And that's, of course, the devastating pandemic we're trying to avoid.

GROSS: Are you still worried about that? Is that still a possibility?

WOLFE: Oh, absolutely, absolutely. We're still worried about it. And the thing to remember is when you look at the diversity - so we do a lot of the work in the birds to try to understand the nature of the diversity of these viruses in birds. They have a huge reservoir of these viruses, and these viruses continue to sort of ping us. They continue to trickle out of these bird species into our domestic animals and into humans.

And so whether it's the particular combination of sort of H5N1 and H1N1 or some other combination, we're really just sort of shuffling these things up, shuffling these things up and waiting for a royal flush. And it's just a matter of time before we get a royal flush.

The good news about this is there are people that follow these things very, very closely, and many colleagues of mine do this, and they - what they do is they'll actually sit down, believe it or not, and they'll plot out the trajectories of what you're seeing in these early surveillance - in sort of clinics around the world, and try to guess what the particular flu strain is going to be like in the coming year.

And then they'll actually use that, a fictitious virus, which they've combined information on a number of viruses, to come up with a sort of estimate virus, which really, for the moment at least, is fiction. And that's what they'll create the vaccines based on. It's a really amazing process, and it gets more and more accurate each and every year.

GROSS: Just curious: Do you get flu vaccines every year?

WOLFE: I get flu vaccines, and I recommend them. I think this is incredibly, one of the most important things we can do to protect ourselves and also protect our communities and our families is to become vaccinated with flu vaccines, as well as a whole range of other vaccines, and I'm happy to talk about all of them.

GROSS: Yeah, I want to get into that a little bit later. If you're just joining us, my guest is Dr. Nathan Wolfe, and he's the author of the new book "The Viral Storm: The Dawn of a New Pandemic Age." He's a microbiologist who studies emerging viruses in the hope of preventing new pandemics. He studies and tracks emerging viruses. He also teaches at Stanford.

You say most pandemics begin with a virus that's transmitted from an animal to a human. Why is it that most viruses start in a bird or another animal, as opposed to starting in a human?

WOLFE: Well, this is part of the - I mean, frankly, as a virologist, part of the fun stuff about what we get to do is we're studying a world of organisms, sort of this unseen world that's virtually unknown. We know very, very little about this.

Some of these things, like viruses, some of the most diverse forms of life on the planet, we've really only been aware of them for 100 years or so. So it's a very different task than, say, studying primates, where maybe you could spend your life studying them and only, you know, perhaps find one new species.

This is something that we find new viruses all the time. Like if you look at your hands, there are a number of new viruses on your hands which we have not yet identified, which are - would be completely new to science.

But having said that, we can start putting together the pieces of what's out there, and some of it is really just sort of common sense, if you will. So if you think that every one of these mammal species has a repertoire of viruses that normally infect them, okay, and these aren't static. Things are moving around. It's not just things are moving from animals to humans. Things are moving between different animal species.

But if that's the case, then, of course, if you look at humans, domestic animals and wild animals as a group, there's going to be many, many more viruses in wild animals just because there's many more species of those wild animals.

And then, of course, the interesting questions become: How do we sort through the different species of wild animals to try to determine where the interesting diversity of viruses resides?

GROSS: So you've actually studied how viruses emerge from animals into human populations. You've studied this in Central Africa. Tell us what you witnessed in Africa among people who still hunt and butcher their meat.

WOLFE: Well, when we started the work in Central Africa - and that's now about 12 years ago - we really sat down and said: Okay, what are the different risk factors for acquiring a new virus? How is it that these things - what are the portals of entry that these viruses use to sort of jump over into human populations?

And, you know, we literally sat down with a number of different behaviors and tried to rank them. And the one right at the very top of that list was hunting and butchering of wild animals. And, look, it's one of these things - we're often very separated, listeners to this program, when they eat their meat, mostly it'll be served to them in a restaurant, or if they buy it from the grocery store, it's going to come wrapped nicely in Saran Wrap.

That's not, by and large, the way that we interacted with meat and we interacted with food historically. It's not, by and large, the way that people in Central Africa and many parts of the world interact with meat.

And when you witness hunting and butchering, you recognize what an incredibly intimate biological interaction this is between us and other mammal species and some of our closest living relatives, some things like other primate species.

You're talking about blood which is inevitably all over hands. You're talking about cuts that'll happen on pieces of bone shard while you are removing a particular organ. And I'm sorry for the graphic details here, but the reality is that there's a tremendous amount of contact.

And it's not contact with one particular tissue. It's contact with all of the different organs and tissue systems. And sometimes these viruses, even if we look at ourselves, at really any animal, they're not evenly distributed between our different tissues. You know, so if you just have contact with skin, or you just have contact with blood, you're getting just a little piece of the diversity of these things.

But if you really hunt and butcher, you're getting the full diversity of contact, and what that means is that the viruses in all those tissues of all those different animals have the potential to jump over. And that's why it's such an interesting behavior and one that we spend a lot of time on.

GROSS: So you're trying to - are you trying to prevent people from hunting in Central Africa, or are you asking them to use vinyl gloves when they butcher the meat? I mean, what can you do for people whose lifestyle depends on hunting and eating what they've killed and still protect them from being the patient zero, where the, you know, the virus carried by the animal jumps species?

WOLFE: Yeah, and we're trying to do two things. Obviously, one of the things we're trying to understand is what is jumping over and getting a sense of that, which is of course important for these populations and people all throughout the world.

And yes, what we are trying to do is to understand how it is we can go about changing behavior. We're actively sort of working to come up with animal protein solutions.

There's wonderful organizations around the world, organizations like Heifer, for example, that we're in active discussions with about ways that we can try to introduce novel sources of animal protein that'll help to allow people to have different, you know, different sources of animal protein so they're not forced to hunt wild game. For the moment, though, I mean, we're there, and mostly our mission is to understand what's crossing over and to try to catch it early.

And this is a big, big problem. I mean, you're talking about tens, if not hundreds of thousands of individuals who are depending on wild game as a protein source. So this is something that we're going to need to sort of bump up a notch and get a lot of involvement in and we're all going to need to take very, very seriously if we're going to be able to address this problem.

GROSS: Now, you've also been asking hunters to collect blood samples of their game. So how are you doing that, and what does it help you do as a virus hunter?

WOLFE: Yes, of course, in the process of our education - we call it sort of the Healthy Hunter Program - we work hard to work folks into alternatives. But the reality is many of these individuals will continue to hunt wild game. And what we ask them to do is we provide them with just sort of a baseball-card-sized piece of paper. It's special laboratory paper, but it looks like any other piece of paper.

And we say if you are going to have contact with this, then we ask you how about just taking a few drops of blood and put it on this paper. And this is sort of the incredible miracle of contemporary molecular biology, is that even if these pieces of paper sit at room temperature for weeks and even months at a time before we collect them, as long as they're dried appropriately, we can bring them back and actually discover not only details about the animal that was hunted, but all sorts of information about the viruses and other organisms that are in that animal.

And so it allows us to very quickly come up with an understanding of the diversity of bugs that are out there that have the potential to jump into us.

GROSS: What's the most important thing you've learned from collecting those blood samples?

WOLFE: Well, we see new things all the time. We find a diversity of new retroviruses that are out there. So, of course, retroviruses, this is the family of viruses that HIV falls into, and we're very, very concerned. This is the part of the world where HIV jumped from chimpanzees into humans.

There's no reason why other viruses in that same class won't have the capacity to jump into humans, and by and large, we don't focus on those. So we've been very, very attentive to those.

We've found a number of new retroviruses in these blood specimens. We have identified new species of malaria that are out there infecting these animals that have the potential to enter into humans. And we're really just starting to burn through this massive collection of blood spots to understand what's out there.

GROSS: If you're just joining us, my guest is Dr. Nathan Wolfe. He's the author of the "The Viral Storm: The Dawn of a New Pandemic Age." He studies emerging viruses and tries to stop new pandemics. Let's take a short break, and then we'll talk more about viruses. This is FRESH AIR.

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GROSS: Let's talk about HIV, which is an example of, you know, a very dangerous virus jumping from animal to human. And the theory that you write about in the book is that chimpanzees contracted the virus by hunting and feeding on a certain species of monkey. And the chimps spread the virus to humans. Is this - do scientists know this for sure, or is this just, you know, one theory among others?

WOLFE: Yeah, it's really beyond sort of one theory among others. We know more about the origins of HIV than we do for almost any other virus that affects us or has affected us in history. And it is, it's just the story that you describe. It's about chimpanzees acquiring these new viruses through their hunting behavior, and then subsequently humans becoming infected with this virus through hunting and butchering of chimpanzees.

And then it's a virus that's spread around the world. But in some ways, the amazing feature for me is not that chimpanzees acquired these monkey viruses in their environment. We expect that. And it's in fact not really that humans acquired a chimpanzee virus, because since chimpanzees are so closely related to us, of course we're going to have the capacity to be infected with a whole range of the different microorganisms that infect them.

What's amazing for me is that this incredibly fundamental and important pandemic - you know, something that we can really think of as sort of a scrape in the skin, in the fabric of humanity, something which has either directly or indirectly affected all of us - that it basically was in humans for 50, 60, 70 years before we even became aware of it.

And, you know, I think it's an important question we should be asking ourselves: Are we willing to live in a world where we'll let these things spread around, just waiting for them to go global before we actually catch them? And I think that's one of the things we're really focused on trying to change.

GROSS: Okay. So you founded Global Viral Forecasting a few years ago, and one of its goals is to stop pandemics, to prevent pandemics. So if your group existed when the HIV virus was first identified, what would you have done to prevent it from becoming a pandemic?

WOLFE: Yeah, and let me take a step back, because really, what our objective would have been would have been to find it and to really make a serious statement about it. And again, what I can tell you is we continue to find other retroviruses.

So had we discovered HIV in a rural village, let's say, in the '60s or '70s, something like that, we would have done what we would have had the capacity with our tools to do at that time, which is we would have studied the epidemiology of that particular virus, just like we're studying the epidemiology of these other new retroviruses that we've discovered.

And you might ask, okay, well, what's that going to do? You know, maybe you're not going to necessarily generate a vaccine. You're not going to - well, we would've known how the thing spread. Okay, so in 1981, when the disease was first sort of identified, we didn't know how it was spread.

And it happened to be seen first in individuals who received blood products and in gay populations. And so, as a consequence, we took a whole range of wrong turns, and we treated the epidemic in its early sort of global spread in a way that was completely, completely wrongheaded.

It took until 1986 before the president of the United States even used the word on AIDS on - you know, in public messages. But we would've known that the virus spread heterosexually. We would have had the - we would have seen it spread. We would have had the potential to take measures to try to control its spread.

As it began to spread more substantially, we would have been thinking about how do we develop vaccines, how do we approach it. I mean, it's the early detection. And the way I think about early detection, it's a little bit like the power of compounding interest, but only sort of in the, you know, in the converse sort of way.

The earlier that we detect these things, the more we have the potential to save lives in the future.

GROSS: Nathan Wolfe will be back in the second half of the show. His book "The Viral Storm: The Dawn of a New Pandemic Age" comes out in paperback next week. I'm Terry Gross, and this is FRESH AIR.

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GROSS: This is FRESH AIR. I'm Terry Gross. Let's get back to my interview with virus hunter Nathan Wolfe. He spent time in viral hotspots like Central Africa, studying how viruses jump from species - how viruses jump species from animals to humans. He's conducted studies on hunters who are exposed to the blood and body fluids of monkeys, bats, wild pigs and other hunted animals.

By collecting specimens from hunters and their prey, he and his colleagues have discovered previously unknown viruses. Wolfe is a visiting professor in human biology at Stanford, and the founder of the companies Global Viral Forecasting and Metabiota. His book is called "The Viral Storm." I spoke with him last year when it was published. It comes out in paperback next week.

Now you write in your book "The Viral Storm" that you think pandemics will increase in frequency. Why?

WOLFE: Well, it's just - there's this amazing picture that I use in the book and I use in all of my presentations, and it basically shows that the air routes present in the '30s and '40s and the air routes present around the world in the last few years, and what you see is...

GROSS: Air travel, you're talking about?

WOLFE: Yeah. These are just like the various sorts of connections that airlines make between different points on the planet. And even if you go back 20, 30 years, there weren't that many lines connecting all of us. And if you look now, you see, basically, a plate of spaghetti. I mean there are incredible connections. Airlines and boats are moving humans and animals around the world in incredible way. The features of globalization have huge consequences on pandemics. And the way that this works is it just connects us so much more closely. So one way to think of this is to go back and imagine a virus that jumped over from an animal into a human, you know, say 100 years ago. By and large, there weren't the levels of connections between us, so imagine a rural village in Cameroon, like the kinds of villages we work in now, or Democratic Republic of Congo. I mean these would have been villages where the virus would have jumped over, and these viruses have always jumped over. They would've spread to a number of individuals. Those individuals would either have died or become immune, and then it would've reached the end of the line and it would have just gone extinct. And that happened on countless experiences, countless times throughout the history of humanity.

Now what happens is those remote isolated villages, rather than the majority, they're increasingly the minority. So every one of these viruses that jumps over into humans has sort of a global stage in which to act, and these animals are moving around at incredible speeds; we're sort of connecting animals and humans in ways that we've never contacted them before, through the ways that we deal with food. And as a consequence, every one of these viruses that jumps over from animals into humans potentially has the capacity to infect all of us.

GROSS: So while we're talking about viruses jumping from animals to humans, do people need to be concerned about pets? Because let's face it, pets sleep on people's beds and they're on people's laps and they're licking the faces of the people they live with. Is that a concern?

WOLFE: I don't think it's an immediate concern, but I think it's something that we need to think through and be a little bit cautious of. Now, and I spent a lot of time in the book talking about this, which is so the longer we have an interaction with a particular species, the more likely that any of their sort of indigenous microbes that would have the potential to harm us on a global scale would probably have already jumped out. OK? So that means that is there something hidden in a dog, per se, or in a cat that's likely to come out and be devastating to human populations? I would say the probability of that is likely to be very low.

Now let's flip that on its head, though. These dogs and these cats are not somehow in this biological vacuum of our home and not connected to different animal species. They have the potential to acquire new viruses from different animals and spread. We saw this very dramatically in Nipah virus, which is a virus that jumped from bats into pigs. Pigs, domestic animals, of course - and then jumped into humans and had a huge devastating effect. We see this very commonly in influenza viruses, which we talked a little bit about.

We see this in a whole range of different things. So could cats or dogs be the sort of unwitting vectors of a virus that could infect them from wild animals and potentially spread in humans? Absolutely. And would this be a huge challenge if it happened? I think it would be a huge challenge, because imagine saying OK, we're going to have to cull massive numbers of dog and cat populations and just try to think about how people in the United States, for example, would respond to that. I don't think they would be lining up with their pets in their arms.

GROSS: I'm just thinking about how you live in a world where the things that are invisible to us are your preoccupation.

(LAUGHTER)

GROSS: You know what I mean? Like you're just seeing like viruses all over the place and probably bacteria too. Did I mention fungus?

(LAUGHTER)

WOLFE: Absolutely. No, and I mean look, that's part of the sort of fun, frankly, of being a microbiologist right now, is we increasingly have the tools where we can understand the nature of this very, very diverse and massive unseen world. And it's - you can't understate how fundamental these are. I often do sort of a thought experiment for my students at Stanford, where you imagine sort of an intelligent extraterrestrial tasked with writing the Encyclopedia of Life on Earth. And from a human perspective, we're all sort of locked up in this notion of oh, it would all be about humans and we'd be most of the chapters. Wrong.

That wouldn't be the way that they would imagine it. For the vast majority of the history on our planet, microbes were the only organisms that existed. All of life was unseen. And even right now the vast majority in terms of mass and certainly in terms of diversity of life on the planet is represented by these microbes. So they're incredibly dominant and yet, we only for the first time now, have the tools that will allow us to start sort of, if you will, putting on the glasses where we can ignore the macro pieces of life and see the micro in a way that's really, really clear. So it's an incredibly exciting time for exploration and discovery in biology. This is not a world where we've discovered everything that's out there. We're only scratching the surface.

GROSS: Along those lines, like the ickiest part of your book I think is describing what you think is on a typical human body, on a typical tabletop, on a typical floor, in terms of microorganisms.

WOLFE: Yeah. I have to say that if we're honest with ourselves, we should see ourselves really as walking, sort of, symbiotic colonies of human and other life - microbial life. Now, there's...

GROSS: Describe that a little bit.

WOLFE: Sure. So OK, if we...

GROSS: What are you and I carrying right now?

WOLFE: OK. So let's just take the cells in your body. If we were, let's say we were to count the number of cells between the top of your head and the socks on your feet. What we would find, and this is going to be a little bit counterintuitive, is that 90 percent of those cells are actually not human cells. Ninety percent of those cells belong to, sort of, the various microorganisms that exist, now primarily, in your gut and on your skin, but also in many, many other sorts of parts of your body. There's tons and tons of microbes out there. Now, there's a little bit of a trick there, which is they are actually much smaller than our own cells, so this is not exactly a story of mass, but it is a story of the number of cells.

And then if you take diversity it gets even more, you know, if you get wigged out by sort of the number of cells, the diversity is even more amazing. The diversity of human genetic information on our bodies and in our bodies is less than a, you know, sort of a fraction of a percent. Most of the diversity that we're walking around with, most of the biological information actually belongs to the microbial world that inhabits us.

GROSS: Now you say that if you could kill all viruses in the world, you wouldn't, because some viruses are probably really helpful and could be helpful in ways that we don't even know. So what are some of the really helpful sides of viruses?

WOLFE: Well, first of all, and I spend a entire chapter in the book, which I call the chapter "The Gentle Virus," sort of going through all this and I feel like it's a little bit of my, my sort of evening exercise. You know, if you're going to be focused a lot on the deadly ones, you have to also think about the ones that are not deadly. And, of course, most of the viruses, the vast, vast majority, only a small needle in the haystack of viruses out there are things that even infect us, let alone have the potential to harm us. Now when a species like our own, sort of, encounters this massive amount of new life, obviously one of the first questions we're going to ask is, is it harming us? Does it kill us? And that's going to be our preoccupation for some time, but I think very quickly we'll get to the point of saying, you know, what is the diversity of viruses in oceans? And it's absolutely amazing. You take a, just a little teaspoon of the water from the ocean and start documenting the diversity of viruses there, it's huge. And the number of viral particles, absolutely amazing, you know, and even in terms of mass in the ocean, they're huge.

The notion that all of these things would be harmful to us, of course, is just a, you know, just a terrible human fallacy, number one. And number two, the idea that if you had, you know, if you could again, flip that switch, that's the thought experiment that you're posing here - is you flip a switch, suddenly all the viruses on the planet disappear. The effects, the ripple effects would be so incredibly profound on all of the microorganisms, in the ocean systems, in coral, in sort of soil communities, would be so dramatic that it's hard to say good or bad, but certainly for us as a fragile little species that's really only existed for, you know, a split second in the history of our planet, we're likely to be very fragile to that sort of dramatic change. And I think that there's every reason to suspect that we would die and probably die out as a species very quickly if we did that.

GROSS: If you're just joining us, my guest is Nathan Wolfe and he studies emerging viruses around the world in the hopes of trying to prevent new pandemics. He's the author of "The Viral Storm: The Dawn of a New Pandemic Age."

Let's take a short break here and then we'll talk some more. This is FRESH AIR.

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GROSS: If you're just joining us, my guest is Nathan Wolfe. He's a microbiologist who studies and tracks emerging viruses in the hope of preventing new pandemics. He's the founder of Global Viral Forecasting and author of the new book, "The Viral Storm: The Dawn of a New Pandemic Age."

In terms of putting viruses to work for us, instead of just being victimized by them, you're hoping that there will be more productive research done in how viruses can help cure or slow down cancer.

WOLFE: Oh, absolutely. And we work closely with the National Cancer Institute. We have a multiyear award from the National Cancer Institute to really, sort of, interrogate tumors and understand the diversity of viruses that are present in them, and I think this is very, very important. Look, obviously if we take a step back, what are the major victories that we've had in cancer? And I'm sure if we had a cancer biologist here they might have a different perspective. But at least as an outsider I see we invest, you know, I don't know what it is. I think the National Cancer Institute, four or five, $10 billion a year and probably NCI and the other organizations, and we're making progress but it's not exactly dramatic progress. But if we look at some of the incredible victories out there, some of these have been viruses.

So, for example cervical cancer. I mean this is a cancer which is devastating for women, women at often, you know, relatively young ages. Women all throughout the planet have had this. It's been something that has been devastating for many, many centuries. All of a sudden we recognize - and this was, you know, the subject of the Nobel Prize a couple years back - that it's really a virus that causes the vast majority of cervical cancer. Wow. Boom. All of a sudden we can go out, we can develop a vaccine against the particular virus. That's exactly what we've done. And so the real question...

GROSS: And you're talking about the HPV vaccine?

WOLFE: HPV vaccine. Exactly. Exactly. And so basically that's a story of knowledge of a particular virus helping us to solve a major problem in cancer. And actually, viruses - and I talk about this in the book - if we spin smallpox eradication on its head, so you may ask how did we eradicate smallpox? One of the most sort of dramatic successes in the history of human public health, and people will think oh, well, you did that through the smallpox vaccine.

OK. Well, what's the smallpox vaccine? Oh, I'm sure that this is this sort of incredible biotech solution that allowed us to - no. It's not a biotech, fancy biotech solution. It's basically technology we've had, you know, for a long, long period of time and this was, you know, early research done by Jenner that basically looked out and saw oh, it looks like people who are milkmaids, that are actually milking cows, seem to have a lower propensity for getting smallpox. Oh, maybe it's this virus that cows have that's not deadly enough to humans to cause them to die, but is strong enough to elicit a response so that they don't get smallpox. And it's basically just by taking a variant of this cowpox virus and not even doing, not adulterating it that much and basically spreading it throughout the world that allowed us to eradicate smallpox.

Basically it's a virus that allowed us to eradicate smallpox.

GROSS: So you are not only exposed to viruses in the United States, you travel a lot to study viruses. You go to places that are the hotspots for emerging viruses and pandemics. What do you do to protect yourself from catching a virus?

WOLFE: Well, one of the things we do, and we deploy this in all the laboratories we work in around the world, and actually help other laboratories to develop them, is incredible procedures to allow people that work in the labs to protect themselves from dangerous microbial agents and also to catalogue these things better, to create better biosecurity and to, sort of, improve the way that we approach them. The approach that we use whenever we deal with any of these is what we call universal precaution.

So the idea is we've got a blood specimen, most likely that blood specimen, even no matter what animal it came from, is probably not going to be deadly to us, but we treat it as if it is. And as a consequence, we're obviously sort of very proud and happy that we've never had an incident where we've had any sorts of problems with any of the folks in our labs anywhere around the world.

Having said that, you know, we certainly encounter these risks. You know, there's risks associated with driving on some of these back roads. There's a lot of risks associated with malaria. I've been infected with malaria a couple of times and it's given me a new sort of respect for how devastating this particular parasitic illness is for the many populations that have to live with it day in and day out. It is absolutely devastating.

GROSS: OK. So, when you're traveling, or when you're just at home in the United States, do you wash your hands all the time? Do you ever wear a face mask? There's a face mask on the cover of your book, "The Viral Storm." I don't know if that's supposed to be sending us a message or not. And are those alcohol-based hand cleansers, the ones that are in the Purell family, are they effective against viruses?

WOLFE: Well, I have to say that I am one of these folks that is not particularly - sort of I don't have a hypochondriacal bone in my body, which I guess you would imagine would be an occupational hazard if you did something like what I do. But, you know, certainly I think that they are - I was asked by the publishers at Holt to put something in there that really sort of spoke to people and talked about what are things that, you know, people reading the book can do.

You know, I think that there's a lot of things that people reading the book can do. And one of them is really just to understand the nature of the risks that are present and to be able to sort through the different kinds of risks. For - I was going to say, for better or worse, but I think it's mostly for worse - we have a media environment now that responds to these infectious disease risks, sort of - first off, it goes crazy and says there's a huge risk and you have to all be careful. And then if it doesn't end up being as large of a risk as they originally advocated, then they'll turn around and say, oh, and the public health officials have completely overblown this risk.

I mean, H1N1 is a perfect example of this. H1N1 from my perspective was - you know, people got mad at the public health community for saying that this was a really potentially dangerous risk. But they were exactly right in saying that it was a dangerous risk.

You know, that anger is sort of like the anger that you would have at a meteorologist that was following a hurricane headed for, you know, Washington, D.C. And that basically followed it and followed it and, you know, the hurricane veered off course and then you shoot the meteorologist for all the preparations you made. That would be crazy.

And these pandemics, you have to imagine, it's like a hurricane but it's like the hurricane that didn't last for three days. It's a hurricane that lasted for years. It's a hurricane that doesn't affect just one city but it affects, potentially, the entire planet.

GROSS: Nathan Wolfe, thank you so much for talking with us. I really appreciate it.

WOLFE: It was a real pleasure. Thank you very much for having me.

GROSS: Nathan Wolfe is the author of the book "The Viral Storm," which comes out in paperback next week. Our interview was recorded last year when it was first published. You can read an excerpt of the book on our website, freshair.npr.org. Wolfe is the founder of the companies Global Viral and Metabiota and a visiting professor at Stanford University. Transcript provided by NPR, Copyright NPR.