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Episode 37: Pandemics: Can Viruses Ever Be Good For The Microbiome?

Episode 37: Pandemics: Can Viruses Ever Be Good For The Microbiome?

Life has changed drastically since our last episode and COVID-19 has everyone’s full attention. We’re all hunkered down, social distancing, washing our hands until they’re raw and boosting our immune systems in every way we know how.   

Of course, as news of the virus has spread around the globe, we’ve also wondered: how do viruses impact the microbiome? Can viruses - just like bacteria and fungi - ever be good for our health?  

To find out, we called on Dr. Dennis Carroll, the former Director of the U.S. Agency for International Development’s (USAID) Emerging Threats Division. In this role, he was responsible for leading the U.S. response to the avian flu, in addition to overseeing the agency’s “Emerging Threats” program spanning more than 30 countries across Africa and Asia between 2009 - 2019.

Currently, Dennis heads The Global Virome Project, an international partnership to detect and characterize future viral threats while they are still circulating in wildlife - enabling the world to better prepare before they spill over into us.  

On this episode, Andrea talks to Dennis about how zoonotic spillover - the transfer of viruses from animals into humans - is more common than ever before, the types of animals that are most dangerous to humans and why viruses like SARS and Ebola didn’t spread as rapidly or widely as COVID-19.   

They also discuss how some unknown viruses may actually be beneficial for us and what the future could potentially look like in the months and years to come.     To learn more about the Global Virome Project, visit  

Resources mentioned on the show: 


On this show, you’ll learn: 

  • What is zoonotic spillover? (2:28)
  • The types of animals that are most worrisome (4:50)
  • Why SARS and Ebola didn’t reach the scale of COVID-19 (11:04)
  • Helpful viruses (15:30)
  • Concerns over the rush to find a vaccine (19:34)
  • Potential future paths in regard to COVID-19 (26:48)
  • Immediate and future ways of boosting immunity (30:26)
  • How different animal production techniques bring different land use dynamics (34:34) 
  • Do spillover viruses come from healthy or unhealthy animals? (35:52)
  • Dr. Carroll’s current project (37:38)

BIOHM gut quiz 


Andrea Wien: Welcome to The Microbiome Report, powered by BIOHM Health. I'm your host, Andrea Wien.

Man, so much has changed in the month since our last show that it feels like a completely different world. Like much of the globe, I'm social distancing while trying to remain productive at home with an infant, not necessarily the easiest thing, but still it's definitely no comparison to the thousands around the world who are sick or who are dealing with six family and friends. The stories from Italy especially have been heartbreaking, and as of the time of this recording, things are only getting worse here in the U.S. I hope that you are well, your family and friends are well, and that you're all holding strong in this difficult time.

To help me wrap my own head around what's going on, I asked Dennis Carroll to join me on the show today. Dennis is the former director of the U.S. Agency for International Development's Pandemic Influenza and Other Emerging Threats Unit. In this position, he was responsible for providing strategic and operational leadership for the agency's programs addressing new and emerging disease threats, which has included leading the agency's response to the H5N1 avian influenza and H1N1 pandemic viral threats. In his current role, he is the director of the Global Virome Project, an innovative 10-year partnership to detect the majority of our planet's unknown viral threats that will pivot our approach from simply responding to outbreaks to proactively preparing for them. Their ambitious goal is to mark the beginning of the end of the pandemic era which we are currently living in.

On this episode, I talk to Dennis about how pandemics like the coronavirus we're dealing with now take hold, and why they're becoming more common. We discuss the potential paths that this coronavirus could take in the next few months, in addition to how our understanding of the symbiosis between viruses and the human immune system is lacking. You can think about this in the same way that we talk about bacteria and how not all bacteria is bad. I also ask Dennis what the future looks like for pandemic relief and what we can do as individuals to help curb the spread of dangerous viruses.

Dennis, thank you so much for joining us today.

Dr. Dennis Carroll: My pleasure.

Andrea Wien: Let's set the stage a bit by defining a couple of things for our audience. Can you talk about what a zoonotic spillover means, and how viruses like this coronavirus that we're dealing with now spread?

Dr. Dennis Carroll: Sure, I'd be glad to. Zoonotic viruses, it's basically referring to the primary reservoir for the viruses that cause epidemics and pandemics. Their point of origin are in wildlife. They're already circulating. Every past and future epidemic and pandemic virus we've dealt with had a preexistence in wildlife populations, rats, bats, non-human primates to shorthand.

What happens is that as these wildlife animals start butting up against human populations or livestock, really as a consequence of our further population-driven expansion into wildlife domains, that we see increased interaction, either direct or indirect, and we create opportunities for viruses naturally circulating in wildlife to what we call spill over. They become proximal to, as I've said before, human populations or livestock, and viruses being what they are, they're always looking for an expanded ecologic niche. They're always looking for a new species to diversify their living space in.

When they have an opportunity to bump up against us, they will jump, and every once in a while, one of those viruses has the right configuration in its binding sites to infect people. We've seen that with influenzas coming from wild fowl into poultry then on to people, or we've seen more directly with the HIV virus, which was a simian virus circulating in primates that made a direct jump from non-human primates into human populations back, say, around the 1920s. Zoonotic spillover is really the movement of these wildlife viruses into people, again, either directly or indirectly by wild populations.

Andrea Wien: Now, do we know how many animals are known carriers of these potentially troublesome pathogens, or do we know which types of animals are the most worrisome? You mentioned fowl, like chickens, and bats, exactly what we're potentially dealing with here with corona.

Dr. Dennis Carroll: Well, principally we're talking about mammalian populations. Viruses circulating in mammalian populations have already established the ability to exist in animal groups which are biologically not that dissimilar from us. We know there are about 5000-plus different mammalian species.

More importantly, it's those species of mammalian populations that have the potential to interact with us. What you see is that there are certain species that are far more reluctant to share ecologic space with us. As we move further into certain wildlife domains, significant numbers of mammalian wildlife will do everything they can to avoid us, but there are others that, in fact, are able to coexist in ecologic zones with us. Those largely are the rats, bats, and non-human primates. Even as we talk about 5,000 mammalian species, it's really that subset that has high-frequency interaction, and that's the key to spillover. You can have a random event where it might be an animal population that we rarely see and we stumble across it, but by and large where we see most of the spillover come from, their point of origin are from animals that have a comfort in terms of sharing ecologic space with us and then we find ourselves butting up against them.

Again, water fowl. It's hard to go out into parks and see migrating ducks in the fall or in the spring. We clearly see significant numbers of bats that can co-roost in areas where we live. If you go into South Asia, it's very common to see non-human primates wandering through city streets of Calcutta or New Delhi. And rodents, of course. They have lived with us in every possible configuration throughout the existence of our own species' existence. Those are the most common, and those are largely the dynamics that favor spillover.

Andrea Wien: Based on your work, and you recently filmed a Netflix special called Pandemic, which doesn't tell you everything, it's safe to see that you saw this coming.

Dr. Dennis Carroll: Well, look, I think all of us who work in this space see coronavirus as no surprise whatsoever. It's not that this particular virus we knew was going to spill over, but we know that, one, the dynamics favoring spillover are increasing and intensifying. That's largely because of population. It's hard for us to appreciate that the world we live in today is profoundly different than at any other point in human history. We have just about eight billion people living on this planet, which is not the norm. 100 years ago, during the 1918, 1919 pandemic, there were 1.8 billion people.

Think about that for a moment. As a species, we've been around for about 300,000 years or so. It took us the better part of our existence to hit the one billion mark, and then suddenly within the space of 100 years we've added six billion people onto this planet. By the end of this century, we'll have tagged on another three, four, five billion people. You can't have that type of explosive growth, expanded footprint on the planet without really disrupting the ecologic balances which have long been part of the world we live in. The big ecologic balance associated with this is this interactive dynamic between us and wildlife.

So as we think about the 21st century, it's really unique in terms of being the age of pandemics, if you will. It's a period when we're going to see these spillovers of wildlife viruses into people happening with an intensity and a frequency unprecedented in human history. To say that I or others were not surprised, it's because we're conscious of the fact that we live in a space where these spillover events are, again, happening over and over and over again. If you look back over the last two decades, we see these spillover events happening about every three years ago.

We're seeing some significant new zoonotic virus jumping from wildlife into people or into livestock in a way that signals that there's an evolutionary event sitting on the edge of creating one of these great pandemic moments. The COVID-19 virus is very much typical of this pattern, no surprise. Again, it's not the first. It's not the last. There will be another, whether a coronavirus, an influenza virus, a filovirus, which is the family for Ebola and Marburg, or flaviviruses, the Zika family. There will be another within the next couple of years and the years after that. This is increasingly a natural pattern of our own existence, which raises some serious questions about, are we prepared to deal with this extraordinary explosion in spillover events and the consequences they will bring to us?

Andrea Wien: Yeah. We can get into that. It appears to be no. But I want to talk a little bit about SARS and Ebola and these other large viruses that have made national news, and why we didn't see those spread around the globe in the same way that we're seeing COVID-19.

Dr. Dennis Carroll: Well, first off, COVID-19 is a pandemic virus. The difference between it and, let's say, Ebola is how easily it can spread from person to person. Coronaviruses, the COVID-19 is a coronavirus, shares properties with influenza viruses, another family, which makes them respiratory. That is, when we talk about it spreading among people, it's really by coughing, sneezing, and largely aerosolizing the virus, which easily transmits from one person to another.

A virus like Ebola is much more difficult to transmit. It doesn't transmit by coughing and sneezing. It's largely through bodily fluids, sweating, for instance, which means that you have to have really close, intimate contact with someone who is shedding an Ebola virus before you can catch it. Even then, Ebola virus only sheds in an infected person the last couple of days of their life, just as they are dying. Coronaviruses and influenza viruses can begin shedding even before we begin showing signs and symptoms of illness. Not only do they spread more easily, they spread over a much longer period of time during the period of infection.

One, pandemic viruses like the coronaviruses and the influenza viruses are far more recognizable as global events. Ebola viruses fall into the class of viruses which are more known as epidemic, that is, because they transmit in such a limited way, that they'll never transmit in a way that makes them a global event. They'll always be localized.

Now, air travel changes that a lot. As we saw in 2014, we had multiple examples of an infected person in West Africa getting on an airline and flying into Barcelona, flying into Dallas. One of the unusual features of this century is that certain viruses which are epidemic local-outbreak viruses now become global epidemic threats, just by virtue of population movement being so easily carried out. We now realize that an emergent threat anywhere in the world, whether it's an epidemic-prone virus or a pandemic virus, is a threat everywhere.

We can't take solace as we might have done 50 years ago if there was an outbreak of an epidemic virus somewhere in remote sections of Africa. Well, today that remote section of Africa is no longer isolated from us. It only takes a car ride to a city with an airport connected to the air global traffic grid. Before we know it, that local event in a remote region of Africa becomes very much a part of our own public health concern. We know more about these viruses that pose immediate threats, but we're becoming intimately more familiar with those viruses which are far more localized because of global travel.

Andrea Wien: Now, when we're talking about the scale of how many viruses are out there and how many have the capacity to infect humans, you wrote in a report in Science mag a few years ago that there's about 1.67 million viruses on Earth, and maybe an estimated 631,000 to 827,000 have the capacity to infect people. Obviously, that's a concerning number if we are talking about viruses that are harmful to humans, but I also thought that you made an interesting distinction that some of those viruses might actually be helpful to us because they have the power to enhance our biology. This enhancement that we talk about with bacteria and fungi a lot on this show is important, because without those things, we wouldn't be able to live. We wouldn't be able to survive at all. Do we know the kinds of viruses that may exist out there that might be helpful to us, and in what capacity?

Dr. Dennis Carroll: Well, that's really an interesting question. The topic of the microbiome is really interesting, because what we know about the microbiome today is very different than what we thought we knew about it 30 years ago. Your point about bacteria is really an important one.

Previously, when we thought about bacteria and bacterial infection, we always saw that as a negative. As a consequence, every bacterial infection was treated with antibiotics, particularly broad-spectrum antibiotics, in order to be able to clear out our system of bacterial infections. Little did we know that, in fact, there were huge unintended consequences with the use of broad-spectrum bacteria, because we're not only wiping out the ones that were causing illness, but we've learned now that there's a significant population of bacteria that reside in us as part of our natural microbiome, that over our own evolution we have grown intimately dependent upon, that there is synergistic relationship between these bacteria that infect us and our own health and well-being.

The relationship with bacteria is far more complicated than we imagined. There are good bacteria and there are not-good or bad bacteria. As we learn more about the good bacteria, we realize that we've put our own health at risk as we've overused broad-spectrum antibiotics. We're now starting to realize that the surge in diabetes and asthma that we've seen over the last two decades may be closely associated with excessive use of antibiotics, and essentially clearing out of our system bacteria which were very closely associated with being able to keep our own biology humming along. We're now seeing things like diabetes, as I mentioned, and asthma leaping out as a direct consequence of wiping out populations of bacteria. We're still trying to sort out the exact biologic mechanism by which these things work, but we understand the absence of these bacteria now have direct consequences.

That said, as we think about viruses now, it's not clear to me that we're not oversubscribing to the bad virus notion, that we see all viruses and viral infections as a negative, that is, a direct threat to our own well-being. As such, we liberally take antivirals as a way of clearing out viral infections. I think one of the very real opportunities we have as we learn more about viruses is to really pay much closer attention to the extent that we may have a much more complicated relationship with viruses than we imagined, not that dissimilar to what we've found with bacteria. It's an open question. There is some early work that suggests there may be examples of synergistic relationships between us and different viruses, so it's something we need to be careful about, not oversubscribe to the exclusive bad virus model, and use the opportunity to learn more about viruses as we go forward and to what extent we may have one of these more complex relationships with one of these coexistent entities on this planet.

Andrea Wien: Now, do you have concerns about this rush to have a vaccine for something like COVID-19? Would that fall into this category that we're talking about, this synergistic relationship potentially?

Dr. Dennis Carroll: Well, we've seen vaccines usually being extremely narrowly targeted, that when we develop a vaccine for, let's say, the yellow fever virus, a flavivirus, it has no cross-reactivity to the dengue virus; or as we've developed a vaccine for the dengue virus, it's had no cross-reactivity with the Zika virus. One of the challenges about vaccines is just how narrowly targeted they are. We don't have broad-spectrum vaccines that play themselves out the same way we have with pharmaceuticals.

That's something to think about, because the reality is is that when a virus like the COVID-19 virus emerges, we have no countermeasure whatsoever, no biomedical countermeasure for this virus, and so it is about social distancing and personal hygiene as our first and only response to this particular virus. At some point, we will have a vaccine, but we know that that will still be a year or more out before that happens. But whenever the next coronavirus emerges, this COVID-19 virus vaccine in all likelihood will have no cross-reactivity, so there will be a desire to create more broad-spectrum vaccines.

There is a lot of work going on for the universal influenza vaccine. We know every year with seasonal influenza, because of the slight mutations that occur between each annual influenza virus, that we have to create a whole new vaccine. That's extraordinarily expensive, and getting compliance and people to vaccinate every year is extraordinarily challenging. Having a universal influenza vaccine could prove a game changer in terms of one shot and forever we don't have to worry about infections from influenzas. But then it raises this broader question that you're alluding to, which is are there examples of influenza viruses that may, in fact, have a positive role to play in our own well-being? We don't know that. That's one of the issues we're going to have to grapple with as we go forward.

Andrea Wien: Yeah, we had Dr. William Parker on last month from Duke University, and he was talking about this theory that is part of the hygiene hypothesis, but he likened it to having a bored teenager. If a teenager is bored out in his community, chances are he might find himself into some trouble if we don't give him something to do. Similar to our immune system, if we have suddenly wiped out everything, every virus, every bacteria, every fungi, whatever it might be that our immune system has evolved to fight against, it gets bored and, to your point, turns to things perhaps like asthma, diabetes, autoimmune disease. It does bring up an interesting point. Have we learned enough to not completely annihilate our immune systems on the other side or make them bored enough to act out in ways that may be just as bad as some of these global pandemics?

Dr. Dennis Carroll: That's absolutely right. I think that the research community really needs to take seriously just how indebted we are to the larger microbiome. We need to understand, what are the codependencies we may have with different groups at there? Again, as you said, fungi, bacteria, viruses.

Again, I mentioned, as a species, we've been in existence 300,000 years. Our existence has been within a larger ecosystem. We always like to think of ourselves as separate and distinct from the world around us, but the reality is we're one piece of a much more complex puzzle. We have to appreciate that. As we've evolved as a species, as we've spread out across the world over this 300,000 years, the relationships we've developed with different parts of the microbiome may be far more interdependent than we could possibly imagine. It's at our own peril if we just blindly go forward and repeat the mistakes of overuse of antibiotics.

We need to be much more thoughtful and insightful as we go forward, and far more cautious about oversubscribing to broad-spectrum countermeasures of any kind. There's a great unknown out there that the research community could really help us shine a light on. What is the nature of that complex relationship, and then how can we better differentiate between those parts of the microbiome that, in fact, do have a negative impact on us and which parts of that microbiome, in fact, we have an extraordinary intimate dependency on?

Andrea Wien: Yeah. Unfortunately, I feel like fear sometimes wins in these scenarios over thoughtful planning and policy, but we can be hopeful. That's the only thing.

Dr. Dennis Carroll: Well, we don't just have to be hopeful. I think we've turned a corner on how we approach the whole use of antibiotics. On the one part, we're trying to be more measured on their use because of antibiotic resistance, but I think we've also begun to understand that we have to be far more selective about when to use broad-spectrum antibiotics because of this complex relationship. I think that as we learn more, we're able to adapt.

I think we can appreciate that not being more selective and targeted in the use of antibiotics isn't putting our lives at risk of infection; it's being much smarter about how we manage an infection. I think that if we can move forward with that much more targeted, strategic use of biomedical countermeasure in the future, we're not making sacrifices by not using broad-spectrum countermeasures. What we're doing is just being a whole lot smarter. We can still get the benefits without the unintended consequences.

Andrea Wien: The Microbiome Report is brought to you by BIOHM Probiotics, the first probiotic designed to balance both the bacteria and fungi in your gut. To check out BIOHM Probiotics, go to and use the code BIOHM10, that's B-I-O-H-M-1-0, to get 10% off.

You alluded to this when you were talking about the influenza vaccine and virus, but let's talk a little bit about viral mutation. A lot of people are thinking about this now with COVID. What does the path forward potentially look like for this coronavirus? Is it going to mutate to something stronger? Does it die out? Does it become a cyclical event? What are the paths that we might be looking at?

Dr. Dennis Carroll: Well, certainly, as you alluded to, we should be looking at whether or not this is the beginning of a seasonal pattern. This is the seventh coronavirus that we've known to have infected humans, four of which are closely associated with the common cold, we have Middle East Respiratory Syndrome virus, MERS, which is circulating out of the Arabian Peninsula, and we have SARS. SARS largely disappeared after the 2003 outbreak.

If the COVID-19 virus plays out as the other five that are circulating as part of a seasonal event, that would be very consistent. We think SARS largely disappeared because it killed of its hosts far too quickly with 10% mortality, didn't allow itself to establish an ecologic niche, if you will, within human populations. COVID-19 virus is far less pathogenic, and so it's reasonable to anticipate that come fall, regardless of how it plays itself out over the course of the summer, that we will begin seeing this coincidence with the influenza season in the Northern Hemisphere and, all likely, the Southern Hemisphere's seasonal influenza as well. If that's the case, it raises serious concerns about how we manage the potential threat.

That said, everything that we've seen about this coronavirus, at least in the four months it's been circulating in humans, is that it does not appear to have the dynamics of mutation that are closely associated with influenzas. Influenzas, by the ability of being able to reassort, makes them far more mutagenic than most other viruses. We're not seeing that play itself out in the coronavirus, which means that if we do, in fact, develop a coronavirus vaccine, that stability in its genetic profile may work to our advantage in terms of having a long-term effective vaccine that doesn't need to be reconfigured with each season, which could allow us to better manage these seasonal events as we go forward.

Andrea Wien: So it's not outside of the realm of possibility for us to think, "Okay, maybe this dies down over the summer, but then pops back up next cold and flu season when the colder weather hits until we have this vaccine that could potentially safeguard us."

Dr. Dennis Carroll: That's certainly a real possibility, though I'm not quite sure it's necessarily dying out in the summer. Hopefully, it will begin to disappear as the seasons get warm, but at this point we haven't seen any indication of that pattern at all. But it would not come as a surprise. It's certainly consistent with how we see other coronaviruses behave.

Andrea Wien: I want to talk a bit about what we can do as individuals to prevent... Obviously, we can't go out into the world with every single person and prevent these spillovers happening in different parts of the country, but what are you doing and your family doing to really safeguard yourself in the immediate, right now with this coronavirus, but also looking forward into the future? Are there ways that you think about boosting immunity that might be different than what we've heard in terms of the general advice of washing your hands and staying away from people who might be sick?

Dr. Dennis Carroll: Well, there's really two ways of looking at that. There's the individual. For this particular virus, obviously really being diligent and maintaining a high level of personal hygiene, and really being very thoughtful about social distancing. As we learn more about this particular virus, one of the really points of concern is that we note that people can begin shedding this virus days before they become symptomatic, which means that as we're talking right now, you and/or I, we both, in fact, could be infected and we could be shedding this virus, even though we feel terrific. So we should always presume right now that we are infected. Even if we're not, it's a really safe way of guarding against inadvertently exposing someone else to infection. And we should assume the other person across from us is infected. Adapt our behaviors in a way that minimizes the opportunity for the spread of this virus.

That said, looking much more broadly about what are the big drivers out there that propel spillover and then amplification and ultimately spread of virus, I'll say that the biggest single driver out there allowing these vents to go forward is land use change. Land use change around the world is the thing that is disrupting the ecosystem the most that is creating this dynamic interaction between wildlife and us, and as importantly, wildlife and livestock and us.

The biggest single contributor to land use change on the planet is livestock production. 75% of all land use change around the world was associated with livestock production, and it just speaks to how the ascendancy of widespread consumption of animal protein as not only the populations grow, but the world today is richer than it's ever been. People's ability to buy and access animal protein has transformed just the sheer size of livestock production around the world. That in itself is the biggest single risk factor we have in terms of potentiating spillover.

To be honest with you, I think one thing we as a people, as a species, have to think about is whether we're overdemanding and overconsuming animal protein, and whether there's a smarter, more effective way for us to access the protein we need without continuing to generate the kind of massive land use change associated with livestock production. I think there is a reckoning that we have to come to facing, whether or not fundamentally the lifestyle of meat consumption which is so characteristic certainly within the United States, but Europe and elsewhere, as the rest of the world, Africa and Asia, where we're seeing this explosive growth in human population over the course of this century, if they begin consuming animal protein at the levels we do, explosive growth in these risks is just unimaginable. So we're going to have to take a step back, ask ourselves, "What's the way forward? Can we better manage how we access protein, and can we be far more thoughtful about the role of animal protein in our dietary habits?"

Andrea Wien: Do we see differences in conventionally raised, these big feed lots and farms that are just raising monocultures of things, versus regenerative farming, which is really much more like a back to the land way of doing things?

Dr. Dennis Carroll: Well, you can actually look. Different species of animal production bring different land use dynamics. By far and away, cattle, goats, and sheep account for, when I say 75%, they probably account for 80% of all of the land use change that is out there. When you look at poultry and even swine, their footprint is far, far smaller. It's beginning to differentiate not only between the species that we consume because of their impact, but I think as we go forward we can have revolutions in animal husbandry that will allow us to be far more efficient than what we've done in the past. I think exchanges driven by artificial intelligence will allow us to think far more efficiently about how we do this production. But pay attention to the species of consumption. They're very much weighted in different ways in terms of their impact on land use change.

Andrea Wien: Do we see these viruses that have the potential to spillover in animals that are healthy, or are these animals that are themselves already sick and infected?

Dr. Dennis Carroll: Well, we see both. I can give you an example. We had traditionally thought that, for instance, influenzas... There's a pattern of wild fowl commingling with domesticated poultry in open-range farms. They'll land in shared water space, they'll spill over their viruses into the poultry, and then the poultry, as they move from farm to market, will further spread the viruses. We've always assumed that the introduction of these novel viruses from water fowl, which have already adapted to live with these without any negative consequences, when they are introduced suddenly into poultry populations, they're very closely associated with relatively fast die-offs. We've seen influenzas like H5N1, once it's introduced into a poultry flock, will kill poultry within 24 to 48 hours.

That said, conventional wisdom is always subject to be turned on its head. In 2013, another novel influenza virus introduced from water fowl into domestic poultry, H7N9, highly lethal when it spills over into people. Poultry were asymptomatic. They were carriers and shedders, and were totally oblivious to the fact they had it. These come in lots of different flavors, lots of different varieties. We're always learning something new that surprises the heck out of us.

Andrea Wien: Dennis, this has been so insightful. I really appreciate the time today and your work. Can you talk a bit, just to end here, on what your current project is and what you're really focused on moving forward?

Dr. Dennis Carroll: Sure. We've been talking about the threats posed by viruses. We've made reference all the way back to 2002, the SARS virus, and all of those other epidemic and pandemic threats that have emerged over the last 20 years. When we look back over how we've responded to those viruses, there's one common rule. We always wait and react. We wait for the virus to spill over into people, and then we react. As we see with the COVID-19, waiting and reacting puts us at an extraordinary disadvantage.

We've been asking the question, why can't we be more proactive? Being proactive means if we know that every virus which is likely to pose a threat to people over the course of this century already exists, it's already circulating in wildlife, then why don't we go out into wildlife and begin characterizing and understanding what those future risks are? Why can't we build a database, a global atlas, if you will, that allows us to identify what animal species carry the viruses that you mentioned, 600,000 or so viruses that we indicate may have the potential to infect us? As we've said, a subset of those may have a negative impact on us. Why can't we go out and begin characterizing, understanding that, not only with species in geographic area they're circulating in, but developing a deep genetic database that allows us to think about being better prepared, both in terms of having new technologies and tools available to release immediately upon spillover? But by knowing the ecology of viruses, why can't we be much more disruptive in preventing spillover in the first place?

I and others have stepped forward to develop a new program called the Global Virome Project. It's basically a global partnership to begin developing this big database that has the potential to turn the sciences of virology from, if you will, a mom-and-pop venture focusing on Ebola virus or focusing on Zeka virus or focusing now on the COVID-19 virus, turn it into big data, not just on individual viruses, but looking at the totality of a viral family. There are 4,000 or so coronaviruses out there circulating, distinct, unique coronaviruses. We know about seven of them. What would it mean if we had 75% of the genetic profiles of all of those coronaviruses?

When we talk about countermeasures, could we develop a broad-spectrum countermeasure to protect us against future spillover? Can we use the power of CRISPR-Cas gene editing to really develop a toolbox of countermeasures that is far more precise and far more responsive should something spill over? But then fundamentally, can we prevent spillover in the first place? We know where they are. We know what animal species they're circulating in. We know their proximity to livestock and people. We can be smarter, more efficient, and far more proactive.

The Global Virome Project is really about just totally transforming our whole approach to future epidemics and pandemics. The 21st century, we still have another 80 years. The world is going to get a lot more complicated. The spillover dynamics are going to be far more frequent and intense. Can we do better in the next 20 years than we've done in the last 20? I think we can. We can be smarter. We can exploit the powers of the machine learning, artificial intelligence, and we can transform everything we think about when it comes to future threats.

People who are interested, we do have a website. It's one word, Take a look. It's really exciting stuff. It's about the future happening today.

Andrea Wien: Of course, we will definitely link to that in the show notes as well.

Dennis, thank you so much for doing this important work, and thank you for the time today. It's been very insightful, as I said, and we really appreciate having you on. Thanks so much.

Dr. Dennis Carroll: Well, thank you, and stay safe. Wash your hands. Social distance. You'll live a long time.

Andrea Wien: Great. Thank you. Be well. As always, thanks for listening to The Microbiome Report, powered by BIOHM Health. Until next time, please be well.


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