Speaker 1: Welcome to Prognosis. I'm Laura Carlson. It's day two nine
Speaker 1: three since coronavirus was declared a global pandemic On Wednesday.
Speaker 1: You heard about how stars Covey too spread from bats
Speaker 1: to people. Today we're revisiting one of our early episodes
Speaker 1: that explores a similar theme. Bats are almost certainly the
Speaker 1: source of this pandemic, but these flawing mammals may also
Speaker 1: hold the clues to stopping the next one. Bloomberg Senior
Speaker 1: editor Jason Gale has more. The story of bats and
Speaker 1: viruses can be traced to an Australian veitnarian, Dr Hume Field,
Speaker 1: the son of a policeman. Hume grew up in various
Speaker 1: parts of the northeastern state of Queensland were developed a
Speaker 1: fast a nation for Australia's native fauna. I've always had
Speaker 1: an interest in animals, and I guess growing up as
Speaker 1: a kid, I can remember my parents saying our human
Speaker 1: lives animals. He's going to be a vet And this
Speaker 1: was really a bit of a throwaway line because nobody
Speaker 1: in our family had ever been to university. Led Alane
Speaker 1: to a five year Mrginry course, but nonetheless, the sort
Speaker 1: of seed took hold. I guess at least with me.
Speaker 1: When I caught up with him, he was in his
Speaker 1: home office in a leafy coastal area southeast of Brisbane.
Speaker 1: You can hear chattering wildlife and vocal pets, as well
Speaker 1: as drought breaking rain. Him graduated from the University of
Speaker 1: Queensland in six He worked for a couple of years
Speaker 1: in a small animal practice, but his interest in wildlife
Speaker 1: led him to pursue further study in the evenings, first
Speaker 1: in environmental science than a doctorate in the mid nine
Speaker 1: It allowed him to combine his love of native animals
Speaker 1: with emerging diseases, a time when the state's agricultural authorities
Speaker 1: were trying to figure out the source of a deadly
Speaker 1: horse disease. He was a virus that infected twenty race
Speaker 1: horses stable in the Brisbane suburb of hend It's thought
Speaker 1: to have started when a mare called Drama Series was
Speaker 1: brought to the stables after she had been grazing in
Speaker 1: a field at Cannon Hill, on the other side of
Speaker 1: the Brisbane River. Drama Series died two days later, and
Speaker 1: subsequently all of the other horses fell ill. Thirteen of
Speaker 1: them died. What was especially alarming about this disease was
Speaker 1: that it crossed the species barrier. A trainer and another
Speaker 1: person tending to the horses became ill with a flu
Speaker 1: like illness within days of Drama series death. The stable
Speaker 1: hand recovered, but the trainer died of respiratory and kidney failure.
Speaker 1: The virus was eventually isolated and named Hendra virus after
Speaker 1: the suburb where it was found. Hume was asked to
Speaker 1: help determine how Drama Series might have caught the virus.
Speaker 1: He went searching the paddock where she had been grazing
Speaker 1: and resumably had become infected. He caught rodents, possums, feral
Speaker 1: cats and reptiles and tested them for hendra virus. When
Speaker 1: the results came back negative, he went searching for clues.
Speaker 1: By the people rescuing vulnerable wildlife Here in Australia, they're
Speaker 1: sometimes referred to as wildlife carrots. So we subsequently broadened
Speaker 1: our search and started using wildlife cares as I as
Speaker 1: a conduit if you like, to be able to collect
Speaker 1: samples from sick and injured animals that were in their care.
Speaker 1: And it was in that process so again quite serendipulous,
Speaker 1: that we actually sample. We were sampling kangaroos, we were
Speaker 1: sampling parsons, we were sampling the usual things, darks, the
Speaker 1: whole range of things that would come into wildlife cares.
Speaker 1: And there were flying foxes on your samples, some flying foxes.
Speaker 1: This was over a period of months, and lo and
Speaker 1: behold we found antibodies to hendra virus and some flying foxes.
Speaker 1: So we looked at some more flying foxes, and then
Speaker 1: we looked at some flying foxes in captive populace and
Speaker 1: the zoos, etcetera. And that's how we identified flying foxes
Speaker 1: as being at that stage are possible rest of while,
Speaker 1: then we went on to do further studies eventually detected
Speaker 1: an isolated virus etcetera, etcetera. And so now flying foxes
Speaker 1: or at least a couple of species of flying foxes
Speaker 1: in Australia are recognized as the primary reservoir hosts of
Speaker 1: hendra virus. Flying foxes aren't actually foxes. There are large
Speaker 1: fruit eating bat with a kind of fox like face
Speaker 1: and expression. They weigh up to a couple of pounds
Speaker 1: and their wings can span more than three ft. The
Speaker 1: finding of hendrovirus and bats was important, not just because
Speaker 1: It helped identify the pathway by which horses and people
Speaker 1: were being infected. It also made scientists alert to other
Speaker 1: viruses bats could potentially carry. About a year after humid
Speaker 1: the discovery of hender virus and flying foxes, another opportunity
Speaker 1: to explore the ecology of viruses and bats presented itself,
Speaker 1: this time in Malaysia, where pigs and pig farmers were
Speaker 1: getting sick. By mid more than two hundred and sixty
Speaker 1: five people had fallen ill with encephalitis or inflammation of
Speaker 1: the brain. Of those cases were fatal. There were also
Speaker 1: eleven cases of either encephalitis or respiratory illness, including one death.
Speaker 1: Neighboring Singapore, scientists found the viral source. It was named
Speaker 1: neiper virus, which had turned out was from the same
Speaker 1: family as hendra virus. Hume was asked to help investigate
Speaker 1: the source. I wanted someone who was who might be
Speaker 1: able to guide and work with him to find out
Speaker 1: the natural reserva. So none of we knew about hander
Speaker 1: and bats. Then we immediately focused, not exclusively, but we
Speaker 1: certainly focused on flying foxes in Malasia, and it wasn't
Speaker 1: soon long before we found evidence of NIPA virus in
Speaker 1: species of fine fox there, just as Hendra virus did.
Speaker 1: The discovery of NIPA underscored their risks that emerge at
Speaker 1: the interface of wildlife, farm, animals and humans. Professor Trevor
Speaker 1: Drew is the director of the Australian Animal Health Laboratory
Speaker 1: at Geelong, just outside of Melbourne. It's carried out key
Speaker 1: research on both Hendra and niper viruses. According to Trevor,
Speaker 1: the emergence of Hendra and then Nipper identified the ways
Speaker 1: in which batborn viruses can spill over it and infect
Speaker 1: other species. And Nipper virus was a disease also of
Speaker 1: fruit bats in Malaysia initially, and that virus got into
Speaker 1: pigs because the they were starting to put pig farms
Speaker 1: into more forested areas, and the feces from the bats
Speaker 1: got into the pig styes and was thought to have
Speaker 1: infected the pigs that way, and it killed hundreds of pigs,
Speaker 1: if not thousands of pigs. NIPA isn't just confined to
Speaker 1: Malaysia over the past decade. It's caused outbreaks in India
Speaker 1: and Bangladesh that have killed dozens of people. We also
Speaker 1: now as also know from incidents in Bangladesh of outbreaks
Speaker 1: of NIPA virus that you don't need the pick that
Speaker 1: the that the bat can actually also infect humans directly
Speaker 1: via drinking out of vessels of palm sap that are
Speaker 1: put onto the tree to to harvest the palm sap,
Speaker 1: and people drink this palm sap, but so does the
Speaker 1: bat and they will come down and the saliva from
Speaker 1: the bat can contaminate the palm sap and infect the
Speaker 1: human directly. So we know that that that is one incident,
Speaker 1: but certainly in Malaysia now they're very very careful not
Speaker 1: to have pig farms near bat roosts. And even more
Speaker 1: dramatic outbreak occurred just a few years later. Severe acute
Speaker 1: respiratory syndrome or SARS, emerged in southern China in two
Speaker 1: thousand and two. It's a deadly a cousin of COVID
Speaker 1: nineteen that quickly spread across the world. Hum Field was
Speaker 1: asked to help investigate its source. And because of our
Speaker 1: experience with bats and hand virus and needle virus and
Speaker 1: growing awareness that there seemed to be something special about
Speaker 1: bats and these spillovera viruses, then we hypothesize that bats
Speaker 1: may play a role in the the origins of stars,
Speaker 1: and so we went down that track. It's interesting to
Speaker 1: reflect on the significance of the discovery of species of
Speaker 1: bats and flying foxes as the natural reservoir of hendra
Speaker 1: virus because really that finding, I think has potentially colored
Speaker 1: the identification of bats, or you know, sort of underlying
Speaker 1: the identification of various species of bats being a socialate
Speaker 1: with this suite of other emerging diseases that we've seen
Speaker 1: over time. If we have the group that Hume just
Speaker 1: referred to also includes a bowl of viruses and list
Speaker 1: of virus which causes rabies, as well as a number
Speaker 1: of coronaviruses, including stars and most likely the one responsible
Speaker 1: for the COVID nineteen pandemic. So what is it about
Speaker 1: bats that makes them such great virus vectors. That's a
Speaker 1: quite unique if you think about it in terms of
Speaker 1: them being a mammal that can fly. So so ba's
Speaker 1: are mammals, they produce milk cyclely young they but they
Speaker 1: have got this amazing evolutionary adaptation or ability to be
Speaker 1: able to fly so highly mobile. They also typically live
Speaker 1: in large populations colonies roost, whether it's the big fruit
Speaker 1: bats or flying fox is whether it's small microbats in caves,
Speaker 1: and typically these groups have mixed species as well. Um
Speaker 1: they're relatively long lived animals as as a taxa. You know,
Speaker 1: flying fox are certainly recorded, I think in captivity to
Speaker 1: live well into twenties. Certainly wouldn't live that long in nature,
Speaker 1: but certainly you know, they live for years. So all
Speaker 1: of these factors are very attractive for mammalian virus survival
Speaker 1: and dissemination, if you like. According to Hume, bats have
Speaker 1: evolved and adapted to coexist with the viruses that infect them,
Speaker 1: and so the thinking was that, well, you know, these
Speaker 1: are just viruses of bats, and the bats are used
Speaker 1: to them because they've evolved with them, and that's why
Speaker 1: the bats don't get sick with these viruses. But if
Speaker 1: they spill into other naive, immunologically naive species, then they
Speaker 1: have a dramatic, simularly dramatic and often fatal infection. But
Speaker 1: more recently people have dug a bit further to try
Speaker 1: to understand if there isn't doing something else going on
Speaker 1: with bats, and it seems that there isn't. Hume now
Speaker 1: works as a science and policy advisor with the Eco
Speaker 1: Health Alliance. It's a New York based NGO that works
Speaker 1: to protect wildlife and public health from the emergence of disease.
Speaker 1: Spill over events are becoming more risky. Bats, as we heard,
Speaker 1: are coming into closer contact with farm animals, but they're
Speaker 1: also coming into closer contact with humans. A key reason
Speaker 1: for that is that bats are losing their habitat. Critically,
Speaker 1: they're losing their natural food source. What you're hearing is
Speaker 1: the sound of gray headed flying foxes roosting. It's dusk
Speaker 1: and I'm sitting on a grassy bank of the Times
Speaker 1: River in the center of Adelaide, the capital of South Australia.
Speaker 1: I'm literally a stone's throw from the University of Adelaide,
Speaker 1: my alma mart behind me, and the Adelaide Zoo on
Speaker 1: the other side of the river. This is a popular
Speaker 1: place for the twenty thousand bats hanging upside down from
Speaker 1: the eucalyptus trees above me. It's a familiar place for
Speaker 1: Dr Mark Ship, Australia's chief ventinarian, who is based in
Speaker 1: Canberra but also grew up in South Australia. Mark is
Speaker 1: the president of the World Organization for Animal Health. He
Speaker 1: told me that bats have taken up residency in Adelaide
Speaker 1: and other urban centers, but not by choice. Yes, almost
Speaker 1: every city in Australia now has a resident roost of
Speaker 1: flying foxes. And the fruiting and the flowering trees that
Speaker 1: these bats normally feed on have been largely removed from
Speaker 1: rural Australia and so they've been forced into urban centers
Speaker 1: and suburban park land where there is some flowering trees
Speaker 1: and some fruiting trees, but these are not the preferred
Speaker 1: diet of the flying foxes and they're putting those flying
Speaker 1: foxes under stress. We've seen a number of incidents in
Speaker 1: Australia over recent years with large scale mortalities of flying
Speaker 1: foxes due to heat events. Here in Canberra we had
Speaker 1: a large hail storm event which killed over three hundred
Speaker 1: flying foxes. It reflects that their their in centers where
Speaker 1: they would normally not be present, and that they're under
Speaker 1: stress when they're in those centers. There's another concern with
Speaker 1: maths roosting places like this where horses are being kept
Speaker 1: less than a mile from here. For us, that the
Speaker 1: concern is that where we have park land, we often
Speaker 1: have horses and we know that flying foxes can transmit
Speaker 1: hendra virus two horses, and that those horses and turn
Speaker 1: can transmit that virus to humans, and and that's a
Speaker 1: fatal disease of both horses and of humans. And then
Speaker 1: and then that there is the risk that the bats
Speaker 1: themselves will will transmit directly to human populations. And there
Speaker 1: are a number of coronaviruses and other viruses that bats
Speaker 1: carry and can transmit to the human population. But there
Speaker 1: are other consequences of the loss of that habitat. While
Speaker 1: these animals can carry some pretty nasty viruses, they perform
Speaker 1: functions vital for the Australian ecosystem. They play very important
Speaker 1: roles in terms of insect control, of pollination and of
Speaker 1: seed dispersal. The role that they play in keeping down
Speaker 1: insect numbers which and and insects can transmit disease, particularly
Speaker 1: in northern Australia, is very important. And then that the
Speaker 1: role that they play in eliminating plants as they move
Speaker 1: between plants and then dispersing seeds where they eat fruits
Speaker 1: and disperse the seeds so that those plants become established
Speaker 1: in other areas is very important and is a role
Speaker 1: that no other participant in the ecosystem can ploy. In
Speaker 1: the mammalian world, lifespan is generally proportional to body size
Speaker 1: and metabolic rate that's defined both these rules. One bat
Speaker 1: species weighing just seven grams or a quarter of an ounce,
Speaker 1: can live for more than forty years. It's one of
Speaker 1: a number of quirks of these critters. Professor Lindfa Wang
Speaker 1: has been unlocking the secrets of bats since the nineties.
Speaker 1: He was the scientist who isolated and characterized hendra virus
Speaker 1: and identified its viralogical cousin Nika. Actually it was Lindfa
Speaker 1: who named the genus to which they both belong, hannaper virus.
Speaker 1: Back then he was working at the Australian Animal Health
Speaker 1: Laboratory just outside of Melbourne. He now heads the Emerging
Speaker 1: Infectious Diseases Program at Singapore's Duke and Us Medical School.
Speaker 1: For the past thirteen years, he's devoted his career to
Speaker 1: studying bat biology and bat immunology, particularly its defense against viruses.
Speaker 1: He's brought a number of researchers along with him in Australia,
Speaker 1: Singapore and now China, where he was born and did
Speaker 1: his undergrad degree in scientific circles. Lympha is sometimes known
Speaker 1: as the batman. People give me the nickname of Batman
Speaker 1: that I tried to clasp them that I actually don't
Speaker 1: started bad, but batmus. Lympha serves on the World Health
Speaker 1: Organization's Emergency Committee, advising the Director General on the current
Speaker 1: COVID nineteen pandemic. It's a reflection of the knowledge in
Speaker 1: his twenty person lab have amassed on these animals, and
Speaker 1: we have been focusing on the question of why that's,
Speaker 1: why that's are so different, why they can carry so
Speaker 1: many laws and themselves do not get sick, and why
Speaker 1: bats lives so long. Consider their living environment and also
Speaker 1: the straps they have during fly and also the pattern
Speaker 1: and they're exposed is much much more than a non
Speaker 1: flying mammal. It turns out that the immune system of
Speaker 1: these flying mammals is different to that of terrestrial mammals.
Speaker 1: Bat's react to infections at an earlier stage, arresting them
Speaker 1: before they cause any disease. That enables bats to avoid
Speaker 1: the damaging inflammatory immune response. Other mammals, including humans, often
Speaker 1: mount in response to virulent infections. So our current looking
Speaker 1: hypothesis is that that's have a much better defences the torrents.
Speaker 1: Pathologists studying COVID nineteen and other pathogenic viruses have observed
Speaker 1: that when the body initially recognizes an infection, various white
Speaker 1: blood cells that consume pathogens and help heal damage tissue
Speaker 1: act as first response wonders. In some severe infections, the
Speaker 1: body's effort to heal itself maybe two robust, leading to
Speaker 1: the destruction of not just virus infected cells, but healthy tissue.
Speaker 1: It's that inflammatory response that ends up being deadly. Bats
Speaker 1: don't suffer the same fate that can defend themselves, launch
Speaker 1: the inflammation, but they don't go over. Okay, So this
Speaker 1: is a very big area of research, and I think
Speaker 1: we human can learn Lympha says he's convinced that's offer
Speaker 1: important insights into the regulation of the immune system that
Speaker 1: may inform ways the human body can better tackle COVID
Speaker 1: nineteen and other viral diseases. So my slogan now is
Speaker 1: that my study is basically looking from that that have
Speaker 1: so much of the features. For one thing, Limpa is
Speaker 1: intrigued that species of that that way is just seven
Speaker 1: grams has a heart that beats more than one thousand
Speaker 1: times per minute during flight. It flies for five to
Speaker 1: eight hours daily and can live for forty three years.
Speaker 1: This is all done with the same heart, with any medication,
Speaker 1: with any in the hygiene. You imagine that, right. It's incredible.
Speaker 1: It's a little wondered that Lindfa is working with cardiologists
Speaker 1: who study the heart muscles of bats, just one of
Speaker 1: a number of medical disciplines he's recruited into his backpack.
Speaker 1: I have been able to mobilize not in passion disease,
Speaker 1: to people, genomics, people immunologists, and the cans of biologists
Speaker 1: and now cardiologists are collaboys. Be just started back. My
Speaker 1: personal dream you have enough money, is to statue a
Speaker 1: bad institute. I think that we have lots to learn
Speaker 1: from that. That's can help us identify what viruses of
Speaker 1: pandemic potential are lurking in nature, as well as ways
Speaker 1: we might be able to mitigate their threat. They're just
Speaker 1: one example of how humans are profoundly affected by what
Speaker 1: happens in global ecosystems. To anticipate, prevent, and responded to
Speaker 1: zase threats in like COVID nineteen means taking an increasingly
Speaker 1: wide angled look at the natural world. That was Jason Gale,
Speaker 1: and that's it for our show today. For coverage of
Speaker 1: the outbreak from one and twenty bureaus around the world,
Speaker 1: visit bloomberg dot com slash Coronavirus and if you like
Speaker 1: the show, please leave us a review and a rating
Speaker 1: on Apple Podcasts or Spotify. It's the best way to
Speaker 1: help more listeners find our global reporting. The Prognosis Daily
Speaker 1: Edition is produced by Topher Foreheads, Jordan's Gas Pure, Magnus
Speaker 1: Henrickson and me Laura Carlson. Original music by Leo Sidrin.
Speaker 1: Our editors are Rick Shawn and Francesca Levi. Francesco Levi
Speaker 1: is Bloomberg's head of podcasts. Thanks for listening, Footable and