＂Will Rats Cause the Next Pandemic？＂ - Steven Belmain
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Summary
In this episode, we talk to Professor Stephen Bellman, an expert in rats and pest control at the Natural Resources Institute at the University of Greenwich, about their spread around the world, their impact on our food supply, and the threat of a rat apocalypse.
Transcript
00:00:04.040
It's still a big problem in many parts of the world.
00:00:10.080
they were taken by great surprise in 2017, 2018,
00:00:22.280
and the wealthy and the cities don't worry about it too much.
00:00:27.040
And, you know, there were thousands of cases and several hundred people died.
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And this is a show for you if you want honest conversations with fascinating people.
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Doesn't get any more fascinating and a little bit different to what we normally do today
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because our brilliant guest today is a professor of ecology at Greenwich University here in London
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who is an expert in rats. Professor Stephen Bellman, welcome to Trigonometry.
00:01:03.360
It's great to have you on the show. Before we get into the very interesting subject of rats,
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tell everybody a little bit about who are you, how are you, where you are,
00:01:12.220
what has been the journey through life that brings you to be sitting here talking to us?
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Right, okay. Well, you might hear from my accent as we get going. I'm an American. I'm born in the
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state of Maine, up in the northeastern part of the states. And so I did my first degree at the
00:01:26.340
University of Vermont. And then while I was there, I did an exchange program and came over to the UK
00:01:30.980
and worked at the University of Kent on an exchange year and fell in love with the country,
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fell in love with a woman and decided to stay in Britain. So I've been here ever since. I did my
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PhD on an insect called the Death Watch Beetle. And now I work at the Natural Resources Institute,
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which is an institute within the University of Greenwich and the institute has a long history
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of working in overseas development research and linked to the empire and science in developing
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countries and essentially around the sort of tropical products and how to to live there so
00:02:06.020
issues with locusts and malaria and the problems there so that history of the of the institute has
00:02:11.060
been for several hundred years working in in collaboration with a lot of institutions in
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in those countries. And so my research is very much based around pest management issues, whether
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that's rodents, which is a big part of my work, but also other aspects around insects and the
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management of crops and health issues related to pests as well. And when Francis was suggesting
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that we get you on, he was like, oh, we've got to get this guy on to talk about the ratpocalypse.
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Is there a ratpocalypse? So are rats about to take over the world?
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Well, there's a lot of them. And I mean, people always have these anecdotes. We never
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farther than six feet away from a rat. I don't really put much in store on that sort of statement
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because it does depend whether you live in the city or in rural areas. But rural areas have
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lots of rats too. I mean, if you live on a farm and you'll just see rats everywhere in the crop
00:03:02.960
fields or if it's livestock. So there are hundreds of rats there in cities such as London and New
00:03:07.180
York and Paris. There are big outbreaks of rats. They're living in the sewers. They're living in
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people's back gardens. And there is worries that the population is growing. I mean, they are related
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to our own agricultural production, our waste in cities,
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So if you're out in the garden feeding the birds
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So I think we really need to think more carefully
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and how we might be exacerbating some of these rat problems.
00:03:37.080
The interesting thing with rats is that wherever human beings went,
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That's right. I mean, if you go down into some very deep coal mines,
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And Antarctica, where people have gone for exploration,
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So whether it's a desert or a place where it's just under snow all the time,
00:04:02.760
rats are living there and adapting because we're there.
00:04:05.560
They're taking advantage of our accommodation that we provide
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and the waste that we produce and the food that we produce.
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And that, of course, has a lot of implications in terms of disease, for example.
00:04:17.760
So because they've been living alongside us, they're going into really dirty environments, down into the sewer,
00:04:23.080
and then coming into our kitchen and spreading those diseases there.
00:04:26.160
So it's a real problem that we've sort of developed ourselves because of the way that we're living.
00:04:32.260
And let's talk about disease, because obviously they were responsible for one pandemic, a very, very serious pandemic.
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which is what a lot of people talk about in terms of pandemics,
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there are actually three pandemics in the history that were related to plague.
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So there was one plague before the medieval plague
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So before that, there was something called the Justinian Plague,
00:05:03.500
And now we are still within what is called the third pandemic of plague,
00:05:07.940
which started in sort of international transport,
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steam ships going around the world with rats on board and they spread rats to a lot of parts of
00:05:15.800
the world which had before not had plague so to the americas particularly peru and the southwest
00:05:20.660
of the united states also have areas where plague can spread and we're still within that technically
00:05:25.660
a third pandemic still but besides plague there's also been pandemics that have been spread on other
00:05:31.560
diseases so hantaviruses it's a group of viruses but in the time of the aztecs and the spanish
00:05:38.020
colonialists coming over. There was some documented outbreaks of a hantavirus, which
00:05:44.060
called massive population collapses at the time. So we should be worried because of that history,
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but also, I mean, their role in the current pandemic. We know quite certainly that rodents
00:05:54.980
were not the sort of the development, initial development of the coronavirus. That was most
00:06:00.560
likely bats, but rodents were certainly involved in the Omicron variant. So what happened is,
00:06:06.400
you know, the virus has come out. It is now spreading among lots of different animal species,
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not just humans. And it's got into the rat population, although to begin with, the rat
00:06:16.820
population was resistant to the coronavirus. But it's got in there and caused a lot of mutations.
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So that's how Omicron is so different from the original coronavirus variants that were around.
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So Omicron was essentially probably somewhere in Southern Africa, probably not South Africa
00:06:32.540
exactly, but it was mutating within mice and rodent populations there and then came out as it
00:06:38.360
is now. So we should still be worried about other coronaviruses and the current coronavirus
00:06:43.780
mutating possibly more in rodents. But I mean, there are many other groups of diseases such as
00:06:51.080
arena viruses we should be worried about. One of the most famous arena viruses is Lassa fever,
0.90
00:07:00.300
particularly Nigeria, Syria, Lyon, and those countries.
00:07:03.180
But there, we've been observing over the last few years
00:07:08.440
Again, out of context, we don't understand why.
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Is it something that we're doing that's different?
00:07:23.600
they didn't really have much of any Lassa fever.
00:07:25.880
And so there are other variants of Lhasa in the Americas,
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particularly South America and other parts of Africa.
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And there are worries about these mutating and spreading to other parts of the world.
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And we need to be careful and start doing more surveillance
00:07:40.080
on some of these other groups of diseases which could result in a new pandemic.
00:07:45.280
Because particularly when you look at New York or LA,
00:07:48.260
I was reading reports that the bubonic plague has returned to LA.
00:07:53.580
Has there? Oh, right. I haven't heard about that.
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I mean, obviously, there's a lot of problems with homelessness and stuff like that.
00:08:03.480
I mean, the southwest part of America where plague is endemic in the wild.
00:08:07.300
So this is like New Mexico, Arizona, quite close to L.A. in that sense.
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Plague is a disease, like many of these bone-borne diseases, they are diseases of poverty.
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So they're often found on reservations of Native Americans where conditions are quite poor
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and people are interacting either with pet cats
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and the cats acquire plague from chasing rats around
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And then you're cuddling your cat and it coughs in your face
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Or is there something about the organism of the rat specifically?
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It's the fact that they are mammals, like we are.
00:09:00.960
So, you know, they're quite similar in physiology terms,
00:09:04.360
which is one of the reasons why we use them so much in medical research.
00:09:08.800
if you first will often test them on model animals,
00:09:13.580
But it is the fact that they're also very numerous.
00:09:15.880
And a lot of these diseases like plague are density dependent.
00:09:19.320
So when you have a lot of rats at very high density, the disease spreads in their population much more easily.
00:09:26.140
And the fact that they're going from, say, these different environments,
00:09:29.960
they're going to dirty environments where there might be a lot of bacteria and viruses around,
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and then they can take those into more clean environments.
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So that's, I think, quite different from a lot of other diseases we worry about
00:09:41.000
because they're in a single species and they only have like a single disease.
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But rodents, we know they can transmit more than 60 different diseases to us.
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Some of those are really scary diseases like loss of fever with high mortality rates.
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A lot of them are just sort of gastroenteric dysentery type diseases,
00:10:00.080
And they're getting into, you know, our food supply,
00:10:03.260
you know, contaminating in the food processing side of things.
00:10:07.920
they may be getting in your house and contaminating the food that way.
00:10:10.820
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00:10:39.840
And I think a lot of people, in the end, they give up.
00:10:45.840
And around the world, we've become over-reliant on a single technology,
00:10:53.160
So these were discovered by accident, actually.
00:10:58.060
this group of coumarin-type compounds were discovered
00:11:01.260
that they lead to blood thinning and prevent blood clotting.
00:11:04.960
We now use them in medicines and sort of warfarin derivatives
00:11:09.880
but in high levels of course it interferes with vitamin k and stops your blood from clotting and
00:11:16.020
the advantage of that with rodents is that they don't notice they are being poisoned so with a
00:11:21.720
lot of the old poisons we used to use they were what we would call acute poisons things that are
00:11:26.520
really really toxic things like strychnine and things that you would use to murder each other
00:11:30.580
which kill really quickly and really painfully but the problem with rodents is i mean they're
00:11:36.060
usually quite cautious when they eat things so they come along and they just eat a little bit
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and they feel ill and almost immediately so it's a bit like us if we go off to a restaurant and have
00:11:46.480
a meal and that later that day we feel really awful i'm never going to go to that restaurant
00:11:50.580
again you really sort of link the two things together and rodents are able to do that too
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if they eat something and they feel ill fairly soon afterwards oh that was really bad food i'm
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not going to eat that and they avoid it so they become behaviorally resistant they didn't eat
00:12:05.140
enough of it to kill themselves so they feel ill but they because they're quite cautious they just
00:12:10.140
take a little bit so the advantage of these anticoagulants that were a fantastic innovation
00:12:15.180
in the 1940s and 50s is that they would eat it and they wouldn't feel ill immediately they'd go
00:12:19.600
home they think about it that was really good food and then they come back the next day and
00:12:23.740
eat more of it and more of it and then they take a lethal dose and end up dying from it several days
00:12:29.860
later often and often they're you know because they feel uh more tired so of course that's what's
00:12:36.520
happening is it's causing internal bleeding and so they feel sort of oh well just go home and go
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to bed and that's often what they do they go back to their burrows fall asleep and die there
00:12:45.260
and so it gets around a lot of the behavioral issues with rodents part of the problem with
00:12:50.780
these compounds we're having now is that they accumulate in the environment so they don't break
00:12:55.340
down. They've been synthetically designed to last for a long time. And so non-target animals are
00:13:02.280
picking them up. So predatory birds and other animals that might eat the rodents, but even other
00:13:07.620
things that are just in the environment are also acquiring these anticoagulant compounds.
00:13:11.840
So there's a lot of legislation to try to stop using these compounds. And getting that balance
00:13:17.760
right is quite difficult. So some countries are talking about banning them entirely,
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Others are talking about, well, we need to regulate them better
00:13:27.580
and make sure that only professionals use them,
00:13:31.260
You do need to know how to use these things carefully
00:13:40.520
So we're in this challenge now where if we do ban these things,
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to develop new alternatives for rodent control.
00:14:00.880
Contraceptives, which we know work with humans,
00:14:10.300
to control their populations in sustainable ways.
00:14:15.120
is they're very prolific, they're very short-lived.
00:14:18.300
So how do you get these fertility compounds in them
1.00
00:14:20.700
and deliver that in a way that would still limit their population?
00:14:32.440
So if we ban them, then we have the opposite issue
00:14:36.540
where particularly farmers, livestock farmers in particular,
00:14:39.740
would be, what are we going to do about all these rats on our farm
00:14:47.540
I mean, poisons are, you know, mortality control, whether it's poisons or using traps.
00:14:52.760
Traps can work in some situations, but they're very laborious to use.
00:14:56.520
So I think in, you know, Europe and America with these intensive farming situations,
00:15:01.340
having someone go around and set lots of traps all the time is really not very cost effective.
00:15:06.300
However, in a lot of the work that I do in Africa and Asia and other parts of the world,
00:15:19.420
And that's about communities working together with those traps.
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And so we've been doing a lot of research on that,
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trying to look at, you know, in small rural communities
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where a lot of people are involved in agriculture,
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They are smart, but we must remember we are smarter.
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this people think you know they they try to control rats they put out some poison or they
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put out a trap and inevitably i will hear within the population over time people say oh they're
00:15:58.000
too clever they're avoiding our traps now or they're avoiding the poison which i mean they're
00:16:02.800
they do learn they are behave you know they're mammals like we are they are able to learn
00:16:07.780
there but there are limitations to to what they're able to learn and i think one of the challenges
00:16:13.800
with a lot of animals, again, it comes back to people and our human perceptions. We anthropomorphize
00:16:19.580
things. We give other animals human characteristics. We do this all the time with our pets and our
00:16:25.100
cats and our dogs and think that they're, you know, being able to really love us the way that
00:16:30.440
we love them. But with rats, we do the same thing. I mean, they're too clever to control that, you
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know, we give them abilities that they really don't have. And one of, again, sort of my jobs
00:16:44.780
It's making people understand what are their limitations,
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you're able to deal with it much more effectively.
00:16:57.320
And I think people, they want to hear those things,
00:17:02.420
they have so much cultural baggage sometimes with rodents.
00:17:07.040
we've got Mickey Mouse and all these sort of protagonists and stories
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the mouses, you know, the main character in the story.
00:17:16.820
And that, I think, clouds our judgment sometimes
00:17:19.200
and makes them, you know, into these superhuman animals.
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a rat's not part, because there are a few types of,
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a few species that I think human beings evolved
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a very strong aversion to from very early days.
00:17:36.440
snakes spiders and a rat's part of that because a rat i mean a rat is basically a squirrel with
00:17:42.660
bad pr isn't it like absolutely they're not that dissimilar it's the scaly tail i think
00:17:47.760
you know if you've got a cute cuddly rat it makes a nice pet and you know people will feed it nuts
00:17:53.400
openly in the park like squirrels yeah but yeah the rats and mice i think because they're they're
00:17:58.180
somewhat nocturnal they sort of skid around and that sort of look of the scaly tail is what puts
00:18:03.260
people off i also do think it is related people have been able to sort of put two and two together
00:18:08.220
around disease and hygiene and sanitation issues and so again in our sort of mind we realize these
00:18:15.100
are things from from you know going back thousands of years we really should not be promoting them
00:18:20.100
and avoid them hey kk do you believe in spring cleaning yes but only when my wife does it in
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And you were talking about population control before.
00:19:48.160
Is that the only way to deal with it, basically to reduce the population of rats?
00:19:52.580
Or is there any way to reduce the way they transmit disease?
00:19:56.140
Well, there are other things we should be doing.
00:19:58.140
And this really, again, comes back to human behavior.
00:20:00.620
It's about sanitation and proofing and hygiene and the way we manage our environment.
00:20:12.400
We're leaving food out and the bins are overflowing.
00:20:20.820
we would have a major impact on rat populations.
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then, you know, they're just not going to be so many of them around.
00:20:30.400
So there are a lot of things that are, you know,
00:20:35.300
You know, you need to try to make sure the rats can't get at the food sources.
00:20:39.440
That's often very difficult if, say, it's a pig farm or a chicken farm,
00:20:45.660
But in urban situations, it really is no excuse.
00:20:54.600
And we're quite removed from it, I think, ourselves.
00:20:56.580
We see them, but they don't really have a big impact on our lives personally.
00:21:00.440
So we can just say, ah, that's someone else's problem.
00:21:06.160
I mean, most rodents, we must remember that most rodent species just live out in the wild.
00:21:14.400
They're just eating seeds. They're usually granivorous, so they're eating different grass
00:21:18.180
seeds and other things they find in the wild. They're part of the ecosystem. Thousands of
00:21:22.160
rodent species live that way and don't cause us any problems at all. There's a handful of species
00:21:26.380
we call the commensal rodents, the pest species. So these are things like the Norway rats and the
00:21:31.080
house mice that cause us problems. They are more omnivorous. And I think that's something they,
00:21:36.880
again, because of that omnivorous ability to eat anything they come across, that means they can
00:21:42.320
easily live in a city and live off our waste whatever kind of waste that is and survive on it
00:21:48.020
wow uh you know sorry francis just i i remember when i was a kid i was flying here from russia
00:21:54.780
and there was a guy on the plane with me who was on his way to he ran an english language school
00:22:00.620
somewhere in east asia and he told me the story about motorbiking around thailand or whatever and
00:22:05.220
he told me a story once he stopped at this guy's house and because he was this western honored
00:22:09.700
guest, the guy, you know, wanted to give him some meat. So he, his wife went outside and took a rat
00:22:16.060
off the drying rack and served it. People, how widespread is the practice of eating rats around
00:22:23.000
the world? You'll find it in different cultures around the world. So some parts of Africa and
00:22:27.640
Asia, particularly the rats are seen as a delicacy. So in West Africa, you have cane rats,
00:22:33.520
they're quite a big rat, often not very much of a pest species living out in the wild, but they do
00:22:37.940
get into sugarcane and some sort of crops, because they're so big and meaty, people are actually
00:22:42.660
have domesticated them. So they're actually grown as a farm animal and sold to local markets that
00:22:49.300
way. And other parts of the world, as you say, in Southeast Asia, sometimes they're served at
00:22:53.360
weddings because they're seen as this, again, a sort of an idea of, of fertility. So the young
00:23:00.280
couple should be eating rats in order to go on and breed themselves. And some places they're
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sort of tinned up in like little tins that you buy in the supermarket well you can get tinned rat
00:23:11.540
you can mate you look excited yeah in the philippines they have something called star meat
00:23:16.340
rats spelled backwards so if you go to the supermarket shelves there and you find star
00:23:21.880
meat that's rat meat in a tin so it's all been you know hygienically produced and well that's
00:23:26.900
okay then put up yeah yeah so i mean in many parts of the world you know they're they're eaten not
00:23:32.720
just out of necessity but because they really like eating them it has a you know a very distinctive
00:23:36.860
taste and and you know why not as long as they are prepared carefully you're not leading to
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some extinction you know and in many you know pest management uh ideas you say well if you can't beat
00:23:50.560
it eat it it's one way of we deal with other pests but there is a risk particularly with your if
00:23:55.740
you're catching a rat in the street and and yeah yeah and i think most people that where they do
00:24:00.760
eat rats they make a distinction between say house rats and field rats okay and normally wouldn't eat
00:24:05.900
the rats that are from dirty environments and are trying to to eat them from from the field and why
00:24:11.220
is there a risk of eating a rat as opposed to eating a chicken or whatever well i guess it
00:24:16.240
comes back to just the number of potential diseases they might be harboring and i think
00:24:21.660
often it's down to the to the way rats are cooked so i mean you can get very good recipes and and
00:24:28.800
things that will ensure that they are cooked properly and you don't have to worry about
00:24:32.200
viruses and bacteria being transmitted. But because sometimes they're quite small animals,
00:24:37.020
they don't actually get cooked very well. So essentially they're just held over the open fire
00:24:41.760
and then you open them up and they're still pretty raw inside. And that's where there have
00:24:47.580
been documented cases of people catching plague, for example, pharyngeal plague, where the bacteria
00:24:52.600
gets into the throat and then spreads to the body that way. And many, you know, gastroenteric
00:24:58.340
diseases could be promoted that way, particularly if you're not gutting the animal, you just eat
00:25:02.280
the whole thing, which in some cultures they do. Right. Don't have your rat medium rare.
00:25:07.460
Yeah, make sure it's well cooked. And how serious is plague in 2022?
00:25:15.300
It's still a big problem in many parts of the world. So just a few years ago in Madagascar,
00:25:21.080
Madagascar is a country that's had plague outbreaks almost every year for the last 120 years. So it's
00:25:27.420
a chronic problem there. But they were taken by great surprise in 2017-2018 when they had a big
00:25:35.440
outbreak that got into the capital city in Tenerife and to other urban areas. And it really
00:25:41.160
caused panic there because normally it's a rural disease. It happens out in poor areas of the
00:25:45.900
country and the wealthy in the cities don't worry about it too much. But this particular outbreak,
00:25:51.300
again, it started in the rural area and it got into the city and then it started transmitting
00:25:55.300
human to human which is what you know if you go back to the black death that's how it was primarily
1.00
00:25:59.900
being transmitted first it comes from the rats but then it gets into your lungs and you cough
00:26:03.880
out an aerosol of blood that someone else immediately inhales and catches plague that way
00:26:08.240
so that's what was happening in 2017 2018 in madagascar in the city all the cases were
00:26:14.300
pneumatically transmission transmitted from person to person so it caused panic and you know there
00:26:19.340
There were thousands of cases and several hundred people died.
00:26:23.300
And because I always understood that it was transmitted by fleas.
00:26:27.820
That's right. That's how it still is classically transmitted.
00:26:33.000
Again, most of these species, they're living out in the wild.
00:26:35.620
They're not really interacting with humans very much.
00:26:37.760
They act as a reservoir for the plague bacterium in their bodies.
00:26:44.700
But then what can happen is those rodent species come in contact with other species
00:26:49.020
that are living in our cities, the urban rodents.
00:26:52.480
And so either the rodents themselves or the fleas
00:26:55.460
jump off those rodents and get onto the other rodents.
00:26:58.020
And those rodent species we call are susceptible.
00:27:04.820
or mass die-offs of rats in cities that contract plague.
00:27:13.560
Well, they bite us because we're the only other thing around to bite.
00:27:17.360
and that's how the primary transmission of plague occurs.
00:27:21.260
If it's not treated, eventually it spreads through your body,
00:27:24.920
you get widespread septicemia, it gets into the blood, it gets into the lungs,
00:27:29.200
and that's how you can then transmit it human to human
00:27:31.500
through sort of coughing out blood that's got the bacteria in it.
00:27:35.380
So it's highly transmissible then once it gets to that point?
00:27:37.780
Once it gets to that point, I mean, even at the bubonic form,
00:27:44.080
So with bubonic plague, you get the classic symptom
00:27:47.160
is the swelling of the buboes, the lymph nodes.
00:27:49.900
So it's either in your neck, your groin, or your armpits.
00:28:04.780
and it just rapidly, your lungs, you have pneumonia,
00:28:12.300
if left untreated. And that's one of the challenges in many of the countries that
00:28:15.780
continue to have plague. People don't seek treatment quickly enough. Antibiotics will
00:28:19.940
clear it if you go to your doctor and get the antibiotics. But if you live in a very rural area,
00:28:24.980
maybe it's days to get to the doctor and to then recognize it's plague and be treated.
00:28:30.400
It's often too late. And unfortunately, people are dying of a disease that is curable quite
00:28:35.160
easily in the right situation. And what's the likelihood of us having that type of disease
00:28:40.380
in the UK or the US, where we have these huge rat populations,
0.78
00:28:48.820
Yeah, plague has been used as a terrorist weapon in the past,
00:28:52.760
and there are still worries about plague being used.
00:28:55.500
Yes, it was used by the Japanese on mainland China,
00:28:58.300
so they loaded up ceramic bombs with fleas, infected fleas,
00:29:02.180
and dropped these over cities to try to cause an outbreak.
00:29:09.640
But, you know, it's a kind of biological weapon, in a sense.
00:29:12.700
The Russians learned how to put it into big intercontinental ballistic missiles
0.96
00:29:27.540
but they could never get the bacteria to maintain its virulence in large cultures.
00:29:33.820
And so, they had these huge labs where they were using,
00:29:40.120
because the bacteria would eventually lose its virile.
00:29:47.940
all these areas like in Kazakhstan and elsewhere
00:29:58.980
But here now, I think our risk of plague naturally
0.99
00:30:03.860
So one of the things we know about plague in modern times
00:30:26.960
again, it's a sort of semi-arid savanna-like environment,
00:30:29.760
which is why, again, it spreads a lot in Africa
00:30:39.380
But of course, in those days, it spread human to human.
00:30:44.260
In fact, we had plague outbreaks in the time of the Black Death
00:30:47.420
in countries like Iceland where there were no rats.
00:30:50.560
So we know at that time there were no rats in Iceland,
00:31:02.260
So in those days, of course, hygiene standards were a lot lower.
00:31:05.180
people, you know, they would move around, they'd have human fleas all through their clothes. People
00:31:09.420
didn't wash very often, their clothes weren't washed. And they were sleeping in communal beds
00:31:13.160
and going to inns, which were infested. Again, stories of, you know, being bitten by human fleas
00:31:18.200
by the thousands. And so we, of course, don't have great evidence of it, but we suspect that
00:31:23.720
those human fleas were probably transmitting plague throughout medieval Europe at that time.
00:31:35.780
Do you have an estimate of how many rats there are in the UK?
00:31:44.280
But it's a real challenge to put your finger on it.
00:31:46.680
It's a lot of effort to try to get those estimates,
00:31:50.800
The ballpark, like there's 70 million people in the UK approximately.
00:31:56.320
So there are 200 million rats living in the UK.
00:31:59.120
I would say easily. It's probably much more than that.
00:32:01.680
There have been some studies that have tried to understand how many rats
00:32:14.480
and they're just living in the soil, burrowing in there,
00:32:17.120
eating the wheat or the maize or whatever it is.
00:32:20.240
And they till the soil, which in itself just chews up lots of rats.
00:32:25.600
And it's literally billions of rats around the world
00:32:30.200
that are just being destroyed in agricultural production.
00:32:35.980
there's a lot of livestock farms that are heavily infested.
00:32:41.380
there's just rats living out there, taking advantage of that.
00:32:48.740
Probably in the cities, I don't think the rat problems are very high
00:32:51.860
simply because, again, it's just access to food and things.
00:32:55.120
So I would say the rural population is probably a lot larger than what you have in urban areas.
00:32:59.480
Yeah, but I suppose the rural population is less problematic, quote-unquote.
00:33:07.020
You know, in urban areas, you know, I think, you know, during the pandemic,
00:33:09.720
there was this sort of increase in reporting of rat numbers.
00:33:14.420
And I think a lot of that's because people were sitting at home
00:33:16.120
looking at what's going on in their back garden,
00:33:20.780
And so the sort of traditional sources of food that people had for rats,
00:33:25.760
you know, the bins at the back of the takeaway were not there.
00:33:29.540
So the rats said, well, where else are we going to go?
00:33:32.480
And so there was a big reportage of more rats around,
00:33:35.540
even though probably the rat population was declining during the pandemic
00:33:38.280
because there was less food around in urban areas.
00:33:40.620
And so what other impact do they have, particularly in cities?
00:33:43.740
We've looked at the disease element of it, which is, of course, huge.
00:33:49.060
Well, I think one of the most traumatic things that I've seen
00:33:59.180
there are stories in the sort of more tabloid press here
00:34:05.780
And, you know, this is usually someone who's very ill in a care home
00:34:10.320
And, you know, they show pictures of her elbow all bitten up
00:34:15.740
In many other parts of the world, it's much worse
00:34:17.760
where you can see babies with their noses bitten off entirely
00:34:21.300
and, you know, sort of real sort of slum conditions
00:34:23.980
where these rat bites, you know, maybe 10% of the population
00:34:27.460
that's routinely being bitten by rats while you're asleep at night.
00:34:30.700
So you're in your house, you can hear all the rats running around
00:34:33.520
and they're crawling all over you, running over you while you try to sleep.
00:34:37.720
And a lot of people complain of disturbed sleep.
00:34:41.520
or you've got food residues on your hands or something like that,
00:34:45.860
the rats will come along and just start licking.
00:34:47.760
they're not trying to eat you usually but then you twitch in your sleep and then they bite out
00:34:53.500
in self-defense really so you some pretty grotesque pictures and people that i've seen who've had
00:34:59.860
really terrible terrible experiences where then it leads to infection and gangrene and people
00:35:06.260
having amputations because of it and you know just getting rat bite fever which again is through
00:35:11.600
bacterial infection getting into the wound and spreading through the body so rat bites i would
00:35:16.260
say is one thing that I would try to avoid. In terms of food contamination, it's really hard to
00:35:23.620
put your finger on it again. It's an anecdote. We know rats are involved in salmonella transmission,
00:35:30.860
but to what extent? It's again, it's a question of how much do we want to invest in trying to
00:35:36.420
understand what the real impact is. In food production particularly, I think we massively
00:35:40.400
underestimate the impact, but no one's looking. And I think with a lot of rat issues, we just
00:35:58.680
Because that's something that gets talked about a lot.
00:36:00.700
If you corner a rat, it will go for your throat.
00:36:13.460
But I mean, I think most animals are if they're cornered.
00:36:16.440
So, you know, if you've got one in your garden shed
00:36:21.020
I mean, its response will be to try to attack you to get away.
0.65
00:36:24.160
I mean, some of the Norway rats you get on farms
00:36:28.260
or in urban areas around here, they're very big,
00:36:32.780
And if you've got a small cat, I've got a small cat at home,
00:36:35.100
and certainly some of the rats I've seen are bigger than my cat.
00:36:40.340
you can see a rat winning in some of those situations.
00:36:48.920
Yeah, I mean, they would certainly try to attack you,
00:36:55.000
Well, you'd be either so scared you'd run out of the way
00:36:57.500
or you would find a way of dispatching it yourself.
00:37:02.480
And then load it into a rocket and send it to America.
0.88
00:37:04.060
A lot of people would get quite queasy about that
00:37:08.440
yeah it's really interesting and and steve what are you working on in terms of your research now
00:37:13.680
are you trying to find solutions to some of these problems or you yeah i mean there's various angles
00:37:19.320
some of it is about sort of developing new alternatives for the poisons and so fertility
00:37:25.120
control is something we've been looking at in a number of different countries evaluating
00:37:29.080
its efficacy so one of the challenges here is that you know you've got a large population of
00:37:34.460
rats that turns over very quickly. So how do you deliver something like a contraceptive to a rodent
00:37:40.300
in a food bait? So it's essentially, you have to put out a bait. It's usually got a poison in it.
00:37:45.020
Will it work when we put the fertility control in there? And again, it comes back to humans and the
0.85
00:37:49.780
perceptions of that. A lot of people say, why are we just going to stop them having babies?
00:37:54.000
We want to get rid of them. And so a lot of it is trying to make people understand that actually
00:37:59.200
this is much more sustainable, more humane for starters, but actually is more ecologically
0.81
00:38:04.740
sustainable than trying to kill them. So if I can try to explain to you what happens when you do
00:38:09.120
mortality control is you kill off a whole bunch of rodents, but you don't kill them all. It's
00:38:13.640
impossible to kill them all. So those that are left recover very quickly. They go through very
0.99
00:38:18.640
rapid breeding and rodents are very good breeding machines. So they can do something called
00:38:24.720
postpartum estrus. So that means as soon as they give birth, they can get pregnant almost
0.98
00:38:29.380
immediately. The next day, they can get pregnant again. So they still have a young litter that
0.95
00:38:33.760
they're nursing. So if it's a mother rat, she's nursing one litter and she's pregnant with the
1.00
00:38:39.140
next. And as soon as those babies are weaned and go off into the environment, she's giving birth
00:38:43.840
the next day. So the gestation period and the weaning period coincide in a number of days.
00:38:50.180
so essentially every month most species of rodent can have another litter of young wow
00:38:55.880
they're just pumping them out so if you kill a bunch what you're doing is you're suddenly opening
00:39:00.880
up the habitat yeah there's a lot of food around because usually the food production is going up
00:39:05.460
this is the beginning of the cropping season and so those babies realize well they have a better
00:39:11.320
survival because there's a lot more food around there's less competition because you've killed a
00:39:14.600
bunch. And so they go through a population explosion, and the population actually can go
00:39:19.900
higher than it would have if you hadn't done any mortality control. So it overshoots. And this is
00:39:26.280
common with a lot of pest issues that we control this way. With fertility control, you stop those
0.98
00:39:31.260
animals from having babies in the first place. They're still there. They're still eating something.
00:39:35.960
But the population, of course, can't exponentially grow as the food production increases.
00:39:40.340
so it's more sustainable but people need to see it at the end of the season in a sense so they
00:39:45.840
have to be patient understand that the damage to their crops is going to actually be lower
00:39:50.160
because you've managed the population and stopped it from going through this boom and bust
00:39:54.020
phenomenon so what we try to do is work with communities so they can understand that
00:39:58.920
but also it's all about timing when you deliver this bait you don't want to just do it all the
00:40:03.980
time so you really want to just deliver it once ideally and have an impact throughout the next
00:40:08.700
few months. So a lot of the research is trying to understand these ecological issues in different
00:40:14.020
sort of contexts to making it work. So that's a big part of my work. Another part of the work
00:40:20.640
is trying to really understand the role between rodent control and disease transmission. So again,
00:40:26.740
it gets quite complicated in ecological terms in the sense you think fewer rats should mean
00:40:30.940
less disease transmission. And with some diseases, that's probably the case, but with other diseases,
00:40:36.280
possibly not. So what can happen when, again, you kill a lot of rats or remove rats, however you do
00:40:42.100
it, those animals that are left might move around more. So they come in contact with more animals
00:40:49.100
further away and possibly spread the disease. So you make matters worse. So trying to understand
00:40:57.140
these dynamics is another sort of fundamental issue. So for example, with plague in Madagascar,
00:41:02.580
we're trying to control rodents. But then what happens to those fleas? And could you actually
00:41:08.320
make matters worse? If you kill those rats, the fleas come off. Are we responsible for causing
0.98
00:41:13.740
a plague outbreak by killing rats? So it's really tricky sometimes. And sometimes these different
00:41:19.260
diseases have different ways of sort of surviving. Some get into water or soil and then are transmitted
00:41:27.160
that way and so that's a another big component of my work is trying to understand what is the
00:41:32.840
best way of managing a rodent population to stop humans catching some of these diseases
00:41:37.920
hey constantin do you love trigonometry i'm from russia i cannot love anything apart from vodka
00:41:46.740
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00:41:52.860
satisfactory and do you like live shows of course but only if it's check-off play about collapse of
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russian aristocracy as they face death and obscurity before the glorious might of the
00:42:05.660
proletariat and the beautiful revolution okay mate well if you like trigonometry live shows
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then get your credit card out for the lads because we're coming to the edinburgh festival
00:42:18.780
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00:42:24.460
industry will treat us like the czars and execute us that's right we're going to be in edinburgh for
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two days only saturday's guest is andrew doyle which is sure to sell out our other guest is leo
00:42:37.820
curse which means when nicola sturgeon hears about it she'll ban us from scotland herself
1.00
00:42:42.620
tickets are sure to sell out and when they're gone they're gone click on the link below and
00:42:48.380
And we'll see you in Edinburgh on the 6th and 7th of August at the gilded balloon Teviot.
00:42:54.800
Come and see us before hordes of left-wing comedians try to put us in gulag.
00:43:00.700
And Steve, there's also a problem as well, isn't there?
0.89
00:43:03.220
The rat is also celebrated or even worshipped in some countries.
00:43:07.380
I remember seeing a documentary about rats and there was a rat temple in India.
00:43:13.060
if you look at the Hindu god Ganesh, you'll often see him riding a rat, like a horse. You're seeing
0.85
00:43:19.480
he's perched on top of a rat, and that's his mode of transport. And again, I mean, because rats and
00:43:25.140
their status as a fertility symbol, people reverberate them in that way. And these temples in
00:43:30.640
India, people openly feed the rats because the rats are servants of the gods, again, to Ganesh
0.81
00:43:35.820
and others. So by feeding the rats, you are helping feed your gods in that sense. So it is
00:43:42.820
a challenge in some communities. I mean, if you think of the Buddhist religion, where you shouldn't
00:43:46.920
harm animals, how do you reconcile that with pest control and killing things like rats? It's often
00:43:53.060
quite difficult. And it requires, again, understanding human psychology and why we do
00:43:59.960
what we do in order to really control a pest problem like rats. And what happens when you
00:44:04.720
have like a rat temple, for instance, in India? Does that then become a hub of disease?
00:44:10.640
We have tried, well, not me, but some of my colleagues have looked into that because you get these big basins of porridge and sort of milky substances which are there and the rats are coming along and eating from that.
00:44:24.620
People have tried to test those substances, but so far I think it's inconclusive that we've found that.
00:44:31.000
There is quite high turnover, so you know that food is constantly being replaced because there's so many rats living there.
00:44:36.140
and the people who visit there, I mean, again, you would really have to do quite a careful study
00:44:41.760
and I don't think that's really happened to understand. Again, maybe because people don't
00:44:45.080
want to know the answer. It's better not to know. So it's interesting, our aversion to rats is not
00:44:50.680
universal around the world. No, not at all. I mean, even in European and Western society,
00:44:56.420
people have pets, pet rats, you know, the fancy rats. They're just nicely colored Norway rats
00:45:03.160
or mice. You know, people have them as pets. They're quite affectionate. I mean, most of these
00:45:07.880
rat species that are pests, they're also very social. So, you know, that makes them nice pets
00:45:12.860
because they can be quite affectionate in that sense. So, I mean, there's a huge industry around
00:45:16.600
that, which has also caused some ecological disasters, for example, in the pet trade. So
00:45:22.040
there's a species of rat called the African giant pouched rat. Again, that's a big rat,
00:45:26.940
long-lived species so people like them as pets they have been sent off around the world for pets
00:45:33.860
and unfortunately they've escaped in the to the florida everglades wow and they are now a pest
00:45:39.620
species there that is driving its own uh invasive ecology within invasive pythons so again the
00:45:47.820
pythons have escaped from the pet trade living in the other glades eating these african pouch
1.00
00:45:52.960
rats in the Everglades as well. It's caused ecological disaster in the Everglades because
00:45:57.040
a lot of the native species, they've all been destroyed and out-competed by these species.
00:46:02.800
But also, I mean, these pouch rats have been used very nicely in helping us clear landmines,
00:46:10.420
for example, so that you might've heard of the Hero Rat Program or the Apopo Program.
00:46:14.860
It's developed by some Belgian colleagues and Tanzanian colleagues where they're using the
00:46:44.500
and then someone can come in and clear that field of bombs.
00:46:49.200
But rats, of course, are perhaps a cheaper alternative to that.
00:46:53.340
They're also using rats to detect TB and screen tuberculosis,
00:46:57.520
which is a huge problem in many developing countries.
00:47:03.700
It means usually a human staring down a microscope all day
00:47:06.680
and often makes a lot of mistakes because they get tired.
00:47:09.540
But again, the rodents are able to smell the bacteria in a sputum sample.
00:47:14.640
So you can just line up a bunch of these patient samples
00:47:26.980
That's incredible because there is a flip side to the rat
00:47:29.820
in that we use them, like you said, in medicine.
00:47:37.860
Yeah, and this is, I think, one of the trade-offs
00:47:42.400
We want to, I think a lot of people see them with aversion,
00:47:49.600
but also just if you think of the diversity of rodents
00:47:52.500
and diversity and biodiversity is really important.
00:47:56.420
And there are really, there are more species of rodents
00:48:00.220
They're, you know, a highly successful group of animals
00:48:08.160
allows them to chew through a lot of materials.
00:48:14.160
You know, they can, you know, get through your door or whatever barriers you might try to put in front of them.
00:48:19.800
And so, you know, that evolutionary behavior has allowed them to, you know, be quite successful in the world.
00:48:43.440
And I think that's something that, you know, some of my colleagues would also come from that background.
00:48:48.400
We often get involved through pest management, which is often focused on insects around the world.
00:48:53.180
A lot more people work on insects than rodents in academia.
00:48:57.200
And so I, you know, when I started working at the Natural Resources Institute, I was a trained entomologist, an insect person.
00:49:27.180
where people were complaining of mainly post-harvest losses.
00:49:32.120
So this is after they harvested their maize crops.
00:49:38.820
And the rats were living in the grass thatching of the roofs,
00:49:44.220
and coming down and eating their maize stored in their houses.
00:49:47.960
And of course, being bitten with plague and all these other problems.
00:49:51.180
And so we started trapping in some of these houses,
00:49:53.480
and I was catching, on average, 100 rats in a house.
00:50:01.480
One room, everyone sleeps together, and the food is there, the kitchen is there all together,
00:50:06.380
and all these rats are up there, and very little was being done about it.
00:50:10.380
So that kind of opened my eyes to a problem that was being neglected,
00:50:14.460
and I felt, well, we need to do something about this.
00:50:17.780
Poisons weren't really an option because they were eating rats in these communities
0.90
00:50:21.140
as well as a source of protein, and so we started this trial on how can we just trap them out?
00:50:27.120
Can we trap them intensively enough with the labor on hand in all these households
0.67
00:50:34.020
I started making contacts with the rodent community.
00:50:48.640
and doing more research in different parts of the world.
00:50:51.560
But we've also touched on the impact they have,
00:50:59.420
rats were very close behind and then they succeeded in wiping out they do they're invasive
00:51:05.020
and you know this has been a big problem on islands around the world where again you've
00:51:09.760
had these sort of bird populations that aren't used to having rats around we've accidentally
00:51:14.560
introduced rats and they just devastate the population you know they're they may be flightless
00:51:19.480
or they're putting their nest scenario where the rats can come along and attack the the chicks and
00:51:23.360
eggs in their nests and so yes we have tried to reverse that so there are some people who have
00:51:29.240
learned how to very efficiently remove rats from islands at great expense, but you can be done.
00:51:35.620
And we've done this quite successfully in many small islands and even some large islands.
00:51:40.140
New Zealand is even trying to do this across the entire New Zealand, you know, two big islands.
00:51:45.580
They have a program to remove not just rats, but all introduced species. So which again,
00:51:51.780
have caused ecological disaster in New Zealand for a lot of native bird species and things. So
00:51:56.880
So they are essentially starting on this idea where we will clear parts of the island and
00:52:02.720
then they put a huge wall around that part to keep out all these invasive species.
00:52:07.260
And then the idea is those walls will expand and expand as they clear more and more of
00:52:13.640
So I wish them luck, it's a huge challenge, but they seem very dedicated to it.
00:52:19.140
It's often a family activity to go out hunting on the weekend, trapping these species out,
00:52:25.300
just rats but you know opossums and other things that they've had there to try to bring New Zealand
00:52:30.240
back to the way it was before all these invasive species came in. And how likely is it that they're
00:52:36.120
going to achieve their goal? If they're if I think they could if they're you know they have to put
00:52:42.680
the money into it and the manpower into it and you know if they keep it up and they seem to this
00:52:47.560
there's a lot of buy-in by the community you know the people of New Zealand have you know they
00:52:52.420
They understand this is important and this is what will do it.
00:52:56.420
If the population is behind it and puts the money into it and the labor,
00:53:02.760
It may take a while, but they already do have some big parts
00:53:06.160
that are sort of already cleared around some national parks
00:53:09.960
and things like that where they've been able to do this successfully.
00:53:12.540
So it's just a matter of being able to expand that
00:53:15.040
across greater and greater areas of the country.
00:53:20.920
So it's not from Australia or New Zealand or those from South America?
00:53:27.120
If we're talking about ratus, so we have ratus ratus, which is the black rat,
00:53:31.660
which we don't really have here anymore, but it used to be a big problem here.
00:53:38.180
So ratus is a genus that evolved in Asia, particularly Central Asia.
00:53:45.320
So if you go to Southeast Asia, you will find a large diversity of ratus species.
00:54:11.200
So there are these sort of global invasive species
00:54:13.680
like particularly ratus and housemus, mus musculus.
00:54:17.280
These are the species that have really spread around
00:54:19.700
in urban environments and when they have invaded new places they've often you know resulted in
00:54:25.220
extinctions and other things being removed from that those areas but then there are often sort of
00:54:31.140
local pest species so in south asia you have bandakota species which again look quite distinctive
00:54:37.220
you get them in india and bangladesh and pakistan and they really are confined to to that region
00:54:43.380
steve it's been an absolute pleasure and fascinating conversation before we ask you
00:54:48.020
our questions from our supporters. We always end the show with one final question, which is,
00:54:53.040
I know you're probably going to say Raz, but I'm going to ask it anyway. What do you think is the
00:54:56.420
one thing we're not talking about as a society that we really should be? Well, I mean, the
00:55:00.780
institute I work at is very much involved in overseas development research. So I think that's
00:55:05.980
one thing I would like to highlight is that I think we sometimes live in a bubble and we don't
00:55:10.720
realize how difficult it is in other parts of the world. And I would really encourage people to start
00:55:16.140
thinking about how can we support more research to deal with some of the problems that we have
00:55:21.900
in say Africa and Asia. Some of these issues are really simple to deal with, but we just need to
00:55:27.400
do some basic research on it. So I would really hope that people will think more about what other
00:55:33.720
people have to go through living with rats or whether it's other pest problems. We hear about
00:55:38.740
malaria, but there are so many other neglected problems and you really have to make an effort
00:55:43.580
to inform yourself about some of these issues sometimes
00:55:45.960
because there's just so many competing interests.
00:55:55.160
And there are so many other neglected issues like this.
00:56:02.520
is my own institute, Natural Resources Institute,
00:56:12.600
Go to the University of Greenwich Natural Resources Institute
00:56:15.200
and there's a little page up there about all the staff involved.
00:56:19.880
So just Google my name and you will find plenty of links that way.
00:56:23.760
Professor Steele Bergman, thank you so much for coming on
00:56:28.160
We will see you very soon with another brilliant interview like this one
00:56:34.580
And for those of you who like your trigonometry on the go,
00:56:42.600
Do they really come up the toilet or is my local plumber having me on?