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David Quammen on the spillover

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In my view, bats aren't to blame fro any of these spillovers. Bats are the unwilling reservoirs of these viruses, and we don't become endangered by viruses that bats carry unless we mess around with bats.

David Quammen

In 2014, when David Quammen’s book Spillover: Animal Infections and the Next Human Pandemic, was published he did not realise that he was predicting our future.

Although Quammen wasn’t surprised when COVID-19 broke out, he was and has been astonished by our ill-prepared governments and has written about key aspects of the science that should inform our responses. In this podcast, hear his insights into pandemics, his far-flung adventures and his enduring passion for telling the stories of science.

This podcast is hosted by Cat (Catharina) Vendl, presented by the UNSW Centre for Ideas and is supported by Inspiring Australia as a part of National Science Week.


Cat Vendl: Hello and welcome to the UNSW Centre for Ideas Podcast. My name is Cat Vendl, and I'm a postdoctoral researcher in marine biology at UNSW. Today I'll be speaking with the author and journalist David Quammen as part of UNSW’s National Science Week program supported by Inspiring Australia. Firstly, I would like to acknowledge the Bidjigal people that are the traditional custodians of this land on which UNSW Kensington is built. I would also like to pay my respects to the Elders both past and present, and extend that respect to other Aboriginal and Torres Strait Islanders who are present here today. Our guest, David Quammen is the author of several fictional novels, but he also wrote multiple books with a scientific background. In his book Spillover, he explores the history behind some of the most lethal and infectious viruses in human history, including Ebola and HIV. David also regularly writes for National Geographic and the New York Times. His work was awarded with multiple prizes. We reach David at his home in Montana, where he lives on mountain time. Welcome to the podcast, David.

David Quammen: Thank you, Cat. It's very good to be with you.

Cat Vendl: David, you started as a fiction writer and published several novels. How did you get into writing about science?

David Quammen: Well, I drifted. I did. I have always been interested in writing. And in the natural world, since I was a kid, since I was a boy of about 10, 11, 12. And, then I had some great teachers of English, and literature. And I never had quite such a great teacher in biology. So, I drifted toward literature. And I started my writing career as a novelist 51 years ago – my first novel was published,  which is astonishing to me – now, it's scary. And then having been fortunate to get an early start as a novelist, a little bit precocious, I discovered, after the first book, how hard it is to be a novelist and to make a living as a novelist. And I wrote and published a few more novels. But in the meantime, I discovered nonfiction writing, and in particular nonfiction writing about science. And I realised that I loved it. I loved it as a reader. And I also loved the idea of writing that sort of thing, myself. So during the course of the late 1970s, early 1980s, I sort of reinvented myself after a period of being out of print, unpublished for 13 years or so. So I paid my dues between the first book and the second book instead of before the first book. Then, in that period, when I was working the menial jobs, I started reading science, started reading nonfiction, started trying to write it. And eventually reinvented myself as a nonfiction writer about the natural world and about ecology and evolutionary biology, in particular, for magazines, and eventually in books.

Cat Vendl: Yeah, so you're a travelling science writer, as well. So you travel a lot. And before the pandemic, I assume you were on the road quite a bit. How much time would you have spent travelling and researching a story in comparison to being actually at home and writing the book?

David Quammen: Well, I do a lot of research, and I travel a lot, or I did before COVID. But I would still spend most of my time, the bulk of my time at home, because the writing takes a lot of time, I don't get the writing done while I'm in the field doing research. Maybe a quarter or a third of my time in a given year was spent travelling, doing research, chronicling fieldwork by biologists of various sorts. And the rest of my time, two thirds of my time was spent at home doing the actual writing. And reading journal papers. I read, I read, read, read. I read lots of journal papers, as well as scientific books, in addition to the interviewing and the observing when I'm in the field with scientists and then I pile it up all on my desk and I drink coffee until I go into a trance and I start to write.

Cat Vendl: So writing under the influence of drugs. 

David Quammen: That one anyway, yeah. 

Cat Vendl: I think Hemingway was pretty good at that wasn't he? Was it a steep learning curve for you to dive into the world of science, since you didn't really have that background before?

David Quammen: It was a long, gentle learning curve. It took me quite a while. When I first started writing about the natural world, writing nonfiction for magazines, essentially, I was writing natural history essays, without much hard science. I mean, natural history is a wonderful branch of the life sciences but without much hard, let’s say, theoretical ecology and evolutionary biology. And so I became an autodidact in that, in ecology and evolutionary biology. And I read, read, read a lot of the important journal papers and the important books. And that took me a long time. Yes. So I started writing nonfiction. And I became progressively more of a science writer than a natural history writer over the course of years.

Cat Vendl: And how would you see your role as a science writer? Do you have a mission? Do you feel like you have a mission beyond just having fun travelling and gathering interesting facts?

David Quammen: Oh, I definitely have a mission, or a sense of mission. It involves a couple of different things, Cat. First of all, I want to entertain readers, I want them to enjoy what they're reading, I want them to turn the page and read the next paragraph. So I never forget that entertainment is part of it. But I also feel a great mission to explain science, to help people understand science better, particularly the life sciences, and the life sciences such as ecology and evolutionary biology that are closely connected with conservation. I care hugely about conservation, I care about the loss of biological diversity. I care about climate change, which is this other horrible problem that runs parallel to the problem of loss of biological diversity. The extinction of species, the loss of populations, unique creatures like the Thylacine in Tasmania. Those are heartbreaking stories, and I tell those stories in my work. And so part of my mission is to, while entertaining people, to make them care about biological diversity and the crisis that we're in, of the loss of biological diversity, and to understand the scientific underpinnings of that subject better. I'm trying to create art, and it'll sound maybe pompous, or presumptuous, but I need to say it anyway, because I believe it. When I create a book, I'm also trying to create a literary work that will last, that has beauty, and intricacy and imaginative value as a work of art. So I'd say those are the branches of my sense of mission.

Cat Vendl: Yeah, I can, I could definitely see that and enjoying writing quite a bit myself. I totally agree that writing is an art and it is very fulfilling to put those thoughts on paper, isn't it?

David Quammen: Yes, yeah. Also terrifying and exhausting.

Cat Vendl: Of course, of course, but that's always part of a good challenge, isn't it? A few years ago by now you published the book Spillover, and I read it back then, and I loved it so much. The book takes the reader on a journey of how some of the most lethal viruses of human history came into the world, including HIV and Ebola. And you did again, you did a whole lot of travelling for that. That becomes pretty clear in the book. And you've been to some quite amazing places. Can you tell us about some of the highlights from your trip when you did the research on the book?

David Quammen: Well, yes, when I did Spillover, it took me about five years, probably three years were spent travelling and researching, and two years devoted to the writing. I was interested in a number of… we should introduce our listeners to the term zoonotic, zoonotic diseases. Zoonosis is an animal infection that's transmissible to humans, and whether it's a virus or a bacterium or some other kind of microbe, if it causes a disease that's a zoonotic disease. 70% of human diseases, human infectious diseases fall into that category. And you as a veterinarian would know about all of these things because veterinarians are hugely important in the study of this subject. And I travelled with a lot of veterinarians, when I was doing this. Wildlife veterinarians, some of whom also had PhDs in ecology. For instance, Hume Field and Raina Plowright, two of my Australian friends in this area, both of them involved with the subject of Hendra disease. Spent time in Queensland, and in the suburb of Hendra in Queensland. And I travelled to the Congo and spent time with a couple of biologist veterinarians who were attempting to take blood samples from gorillas to look for antibodies against Ebola virus, because Ebola virus is very virulent in gorillas and in chimpanzees, as well as in humans. I travelled with another veterinarian ecologist to Bangladesh, where we spent time on the roof of a warehouse, trapping giant fruit bats. He was looking for Nipah virus in those fruit bats. In China, I crawled into caves with another biologist who was looking for SARS, the original SARS, what we now call SARS 1. This was long before our current pandemic. I've spent a lot of time in Africa for National Geographic as well as researching books. the Democratic Republic of Congo, Republic of Congo, Gabon, Cameroon, those places, I spent time there. I retraced what scientists now understand is the route that the HIV virus took after it spilled out of probably a single chimpanzee into a single human, in the southeastern corner of Cameroon around the beginning of the 20th century, around 1908, give or take a margin of error. And then slowly, slowly worked its way down river, to the great cities of the Congo, as they were then, Leopoldville, in Brazzaville, now Kinshasa and Brazzaville. So I travelled following that story. I loved the travel, I love the research, but I love the writing too. I love to bring the notebooks and the journals home, piling them up on my desk, and then using fact, as though the facts were small pieces of colourful ceramic tile, and I'm creating a mosaic. And that's the way I think of my job.

Cat Vendl: That is pretty amazing. And I have to say, that's what the book seems like, like it's just a collection of very interesting stories, which also happened to be true. I have to point out when you mentioned the story about HIV, and that was probably the most, one of my most favourite parts of the book. And I can only recommend everyone who is interested in HIV, and it came into the world to have a look at that. And I think the story about HIV is also published separately, isn't it? 

David Quammen: It is. It's someone's idea, I think it was my British publisher who had the idea. Why don't you take the 100 or 120 pages that are devoted in the book, this long, long chapter devoted to the story of the origins of HIV. And we could publish that free standing, as a small book, you could write a new introduction to it, and make it self contained. And so I did that, and that book is published as The Chimp and the River. So if anybody wants a small sample of my work without committing to a 500 page book, they could try that little book titled, The Chimp and the River. That was the most ambitious and the riskiest part of Spillover for reasons that, you having read it, can probably understand. I did some things in that, while writing nonfiction scrupulously letting the reader know what was fact and what was not. I also took this imaginative parenthetical trip with a character I created, that I called the Voyager, a man who carried the HIV virus down out of the southeastern corner of Cameroon, to the big cities of the Congo, I created a hypothetical scenario by which that event might have happened, or something like that event. And it was a little bit risky, but I've been gratified by the responses of people to it, they seem to have taken it in the way that it was intended, and not confused it with being fast and loose with facts. Well, writing a nonfiction book.

Cat Vendl: Talking about risky, during your travels, and you mentioned quite a few situations like rolling into caves and China filled with, I'm sure, 1000s of bats and stuff like that. Were you ever afraid that one of the diseases you were researching would spill over to you?

David Quammen: I was cautious, I was weary. There were times when my pulse beat a little faster. Afraid is not the word that I would use. I was always respectful of these viruses. I was morbidly fascinated by these viruses, just as the scientists are who make careers out of working with these very, very dangerous viruses. They find a certain awe in these viruses the same way other biologists find awe in lions or tigers, which are also dangerous, and so I shared in that. The first time I put on full PPE, it was in a corner of Cambodia near the Vietnamese border, and I was going out with a biologist, and we were looking for, sort of looking for high pathogen avian influenza, but basically all we were doing was vaccinating chickens against Newcastle disease. Which is a very infectious disease, as you know, in poultry. I'm sure all veterinarians know a lot about Newcastle disease. And so we were looking to vaccinate chickens in this village for Newcastle disease so that these people wouldn't lose their poultry. But at the same time, we were sort of scouting for avian influenza. And so when I dressed up in my Tyvek suit and the gloves and the boots and put on the goggles and the headlamp, and the double gloves, for the first time, I was sweating a bit, my heart was beating a little bit fast. And I thought, here we go, this is the real thing, or something much like it. It focuses the attention.

Cat Vendl: I can believe that. Let's have a chat about bats. So they have a recurring role in your book. They definitely aren't to blame for all the diseases you research in the book. Definitely quite a few viruses that originated in bats. And the COVID19 virus is probably no exception, from what we know today. So can you tell us a bit about what is so special about bats, in a way, that makes them such good transmitters for all those viruses? Because I like in comparison, I haven't heard of any viruses coming from koalas or elephants that spill over to people. So what is it about bats?

David Quammen: Well, it's an important question, and I'm happy to answer it and talk about it a little bit. I'll go back to a phrase that you used without picking on you because it's a natural thing. And you said bats are to blame for a lot of viruses. In my view, bats aren't to blame for any of these viruses. Bats are the unwilling reservoirs of these viruses. And we don't become endangered by viruses that bats carry, unless we mess around with bats. They don't seek us out. The bats generally don't seek us out, and the viruses don't seek us out. So when we interfere with bats, which of course are wonderful animals, highly diverse, extraordinary in evolutionary terms. When we interact with bats, we expose ourselves to a lot of viruses. It's true. They do carry a lot of viruses that are known to be among the dangerous pathogens that come from animals. You know, Marburg virus, which is a relative of Ebola. maybe Ebola, but we don't know that for sure. Hendra virus in Australia, Nipah virus in Bangladesh and Malaysia, rabies may have originated in bats. Australian Bat Lyssavirus, which is a variant of rabies, right? And a number of others. So bats, bats, bats, what is it about bats? Well, a couple of things. First of all, bats are extraordinarily diverse, 1400 species last time I checked, they are more diverse than any order of mammals, except, I believe, rodents. And rodents, by the way, carry a lot of viruses too. So they're seeming over-representation among the reservoir hosts of dangerous viruses, to some degree, probably reflects their over-representation in the diversity of mammals. But there are other things too, bats live long lives, they can live 18,20 years. A bat the size of a mouse can live 18 or 20 years. They live and roost together in huge aggregations. And those two things, long lives and roosting together in clusters of 60,000 individuals, are great situations for continually recirculating viruses in a population. And then, finally, there's the fact that they seem to have immune systems that are different from other mammal immune systems, immune systems that are more tolerant of alien presence, including the sort of alien presence that you find in the molecules on the outside of a virus. So their immune systems respond less, they become inflamed less, they have less of an immune reaction against strange microbes in their bodies. Why is that? Well, because scientists are studying this now. But a possible answer is because the very fact of being flying mammals puts extraordinary stress on their physiology, on their metabolism. And that stress tends to release certain molecules from their own cells. Free radicals, in the technical term, I think. And their immune systems, if they had sensitive immune systems would react to those molecules, those unusual molecules floating around in their blood because of the stress of flying, and so they would have autoimmune disease. It seems that evolution over 30 million years or so, has protected them against that. Has buffered their immune systems in order for them to tolerate the physiological detritus in their own blood streams from the stress of flying.

Cat Vendl: That is super fascinating, especially because you're saying it sounds a bit like that their immune system is a bit on a, yeah, an energy saving mode in a way, not fighting everything that comes its way. But on the other hand, most of the time, at least, they don't get sick from those viruses that carry themselves. Is that right?

David Quammen: That's correct. As far as we know. The viruses that I've mentioned are not known to cause serious disease in bats. There may be other viruses that do cause serious disease in bats, but we don't, we haven't discovered those as human pathogens. So yeah, I use the term reservoir host again, you as a veterinarian will know well what a reservoir host is. But a reservoir host is the kind of animal, the species of animal that a virus or another pathogen lives in over the long term, inconspicuously with some sort of balance, some sort of mutual tolerance. During the periods of time when that virus is not spilling over into humans and causing some sort of a fearsome disease outbreak, like an outbreak of Ebola or COVID-19. They have the advantage of stability and refuge and they do not cause the bats acute inconvenience. So it's a harmonious, a relatively harmonious situation. A sort of a symbiosis. Well, no, it's not a symbiosis, probably because the virus probably don't provide any positive benefit to the bats.

Cat Vendl: Well, it could only be a symbiosis if it prevents everyone from touching the bats, because they know like, well, if I eat that bat, I might get sick. 
David Quammen: It’s true. That is true. 

Cat Vendl: But hopefully in the near future, the word will spread a bit more.

David Quammen: That’s sort of cultural symbiosis.

Cat Vendl: That's right. Yes, indeed. Let's go back to pandemics a bit more broadly. So you've done all this research on different pandemics that have spilled over into the world in the past of human history. So when COVID19 finally hit last year, were you surprised at all that this could actually happen, that this was happening?

David Quammen: No, I was not surprised at all. The scientists that I talked to while I was researching Spillover, were telling me and I say this near the end of the book, beware of coronaviruses. Beware of this group of viruses that evolve very quickly. They're called single stranded RNA viruses. Their genomes are RNA, rather than the more stable double helix of DNA. So they mutate relatively frequently. They can switch sections of their genome from one strain of virus to another, they're constantly changing. And therefore they're capable of fast evolution. The corona viruses, the influenzas, and the group called the paramyxoviruses, which includes measles and a number of others. Those are the ones that 10 years ago, disease scientists were telling me, we needed to be concerned about. And they told me yes, there is a pandemic coming. It'll probably be caused by one of those kinds of viruses, an influenza, a paramyxovirus, or a coronavirus. How bad will it be? Well, it depends on how humans react. The only thing that surprised me about COVID19, as it started up a year ago, January. Was how unprepared we were to deal with it, particularly my country. Catastrophically unprepared, incapable, unwilling, in denial. So we became one of the disaster areas in the world, despite the fact that we have all these advantages, all these resources, all these smart scientists and, and wise public health people. We had terrible leadership. We had a president, I can't recall his name right now. But he was a narcissistic moron, and he did all of the worst possible things. And it wasn't just that, but that's certainly contributed to the disastrous situation in the US, but other places in the world had very mixed responses too. Australia did quite well, New Zealand did quite well, Singapore did quite well. China did quite well, after they locked down the city of Wuhan, and other places, suffered terribly. Italy suffered terribly. So I was, I have been, I've been puzzled, and constantly, in a way, surprised by the virus, or at least, I've been unable to see what's coming with this virus except that it is extremely capable of evolutionary adaptation. So the variants now, the Delta variant, this is not surprising. This is pure evolutionary biology. We knew that this kind of a virus would be capable of this kind of adaptation. The scientists knew, the public health people knew, and the political people refused to listen, except the best political leadership.

Cat Vendl: Would you say there's anything different about the current pandemic then? Yeah, pandemics in the past and infectious diseases in the past that sets COVID19 apart?

David Quammen: Well, in some ways, this is a repetition of patterns. Single stranded RNA virus, in the 1918 influenza pandemic that killed 50 million people, was the single stranded RNA virus. Corona viruses have hit us before. But this is very different from SARS 1 and very different from MERS, the other two highly pathogenic coronaviruses that have infected humans. Why? Because this one is – part of what's unique about it – this one is the nightmare combination of factors. It is a virus that is extremely transmissible, not just from human to human, but from humans, to cats, from humans to tigers, from humans to gorillas, from humans to ferrets, from humans to mink. It has a broad adaptive capability and a great capacity to change. In humans. It also has this capacity that SARS 1 did not have, which is to transmit from asymptomatic people. To infect people and leave them healthy for a period of time, while it gathers in great concentrations in their nasal pharyngeal, their upper airways, and spreads to other people. At the time of SARS 1, it had a mortality rate of about 10%. Killed about one person in 10. Dangerous, dangerous virus, but it wasn't as transmissible as this virus. It was taken very seriously, this virus has not been taken seriously enough, by a lot of people still. Why? Because it's got a relatively low case fatality rate, only about, what are we figuring now? Maybe 1%, depending on this on the health care situation. So it's 10 times as lethal as the average influenza and 1/10 as lethal as SARS. But it has this capacity to spread from asymptomatic hosts, and that is what has made it one of the world's most successful viruses, in evolutionary terms. And so those factors about it, plus the fact that we are now so interconnected, there are 8 billion humans flying around the world constantly, and shipping products around the world, and shipping viruses around the world, as we do that, and those are the factors that have made this experience uniquely bad. And yet, as bad as this experience is, this is not nearly as bad as a pandemic in the 21st century could be, can be. It could be much worse than this with the next virus, if it happens to be a high pathogenicity, avian influenza that adapts to transmission from humans to humans, or something else.

Cat Vendl: You talked a lot to two researchers, as you mentioned on your travels, and just general research for your book. And I would like to ask you, as a science communicator, you are now, in your role. Do you think that most researchers are actually doing a good job in getting their messages and their findings across to the public? Since this is one of the, like, they have one of the key roles, right? In this pandemic? To get across what's actually happening. What is this virus? What is happening to us? What's happening with the virus? Or do you have any recommendations? What could researchers do a bit differently to be more heard and more understood by the public and policymakers?

David Quammen: Well, it's important for science to be communicated to the general public. You're absolutely right. That's hugely important. It's important for all citizens to understand a bit about science, to respect science, to trust science, to be willing to support science financially and with their votes, and therefore the science needs to be shared with them, explained to them. And there's pressure on scientists to do that. Pressure from their institutions, pressure from their funding sources. I'm sympathetic with that pressure. Being a scientist, being a field scientist, or laboratory scientist, is a hard job. I'm not one. I've watched people do that job and I know how hard they work. Some of the toughest people I know, physically as well as intellectually, are field biologists and disease ecologists. So their jobs are tough and demanding. To say that they also need to be good science communicators is adding another bag of sand to the burden that they carry. And I think that that's unfair. Some scientists happen to be great communicators, as well as serious scientists, Frank Macfarlane Burnet from Australia, and JBS Haldane, from Britain, and a number of others, Lewis Thomas, and there's a whole list Richard Dawkins, etc. But those are exceptions. The average scientist working long hours, I think, should not be made to feel guilty about not communicating her or his discoveries to the general public. And part of the reason I feel that, is because that's my job, and I want to do that job. I don't want to be put out of a job. And not just me. But you too. You're a science communicator. And all of my colleagues in science writing. This is our job, to be the intermediaries. So what I say when scientists ask me about this, and sometimes scientists ask me, well speak to us about how to be better science communicators. One of the things I say is, the best way you can be a science communicator is choosing carefully to trust a limited number of good science writers, and maybe science broadcasters. Choosing them carefully based on whether they're devoted to accuracy, whether they do their homework, whether they're really committed to clear explanation, and not whimsical storytelling, whether they don't blur things, whether they don't get things wrong, they double check with you. Pick the right people, the right women and men who are science writers, and then trust them. Give them time, give them the opportunity to see your work and understand it better. And then let them be the science communicators on your behalf.

Cat Vendl: I think David, that is really great advice. And yeah, I wish we had many more of you out there. I think that would really definitely help. Unfortunately, this is all we have time for today. But thank you so much, David, for sharing your insight. I've really enjoyed this conversation.

David Quammen: You're welcome. You're very welcome, Cat. pleasure to talk with you. It's a pleasure to be part of the UNSW Science Week. I'm honoured to be included. I love Australia.

Cat Vendl: Well hopefully we will have you back very soon when –

David Quammen: I hope so too. 

Cat Vendl: – borders open. To hear about upcoming events and podcasts. Please subscribe to the UNSW Centre for Ideas newsletter and visit the Thank you for listening.

David Quammen

David Quammen

David Quammen is the author of The Song of the DodoMonster of GodThe Reluctant Mr Darwin and Spillover: Animal Infections and the Next Human Pandemic among other books. Spillover was a finalist for seven awards and won two: the Science and Society Book Award from the National Association of Science Writers, and the Society of Biology (UK) Book Award in General Biology. He has been honoured with the John Burroughs Medal for nature writing, an Academy Award in Literature from the American Academy of Arts and Letters, an award in the art of the essay from PEN, and (three times) the National Magazine Award. Quammen is also a contributing writer for National Geographic.

Catharina (Cat) Vendl

Cat (Catharina) Vendl

Cat Vendl is a wildlife health researcher and science communicator in the Inter-Disciplinary Ecology and Evolution Lab at the Evolution & Ecology Research Centre in the School of Biological, Environmental and Earth Science at UNSW Sydney. In April 2020 she completed her PhD in the Mammal Lab at UNSW, where she investigated the respiratory microbiome of whales and dolphins and its potential use as an indicator for individual and population health. Cat also co-hosts The Boiling Point, a weekly science radio show and podcast, where she discusses fascinating findings in biology, astronomy, psychology, and interviews researchers about their work. Follow Cat on Twitter: @ScienceCath

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