Ecosystems and Disease, featuring Dr Rory Gibb

PROFESSOR PHILIP SCHOFIELD (INTRO)

Hello and welcome to Series 3 of The Greatest Good, a UCL Press Podcast. I’m your host, Professor Philip Schofield, and Director of the Bentham Project here at UCL. 

Jeremy Bentham, and 18^th– and 19^th-century philosopher, was the intellectual inspiration for the founding of University College London.

In this series, we focus on the intersection of Bentham’s ideas with current thinking on climate justice, in conversation with leading UCL academics.

DR RORY GIBB (INTRO)

Mosquito species are moving and establishing populations in new places and the pathogens are following. So just last year we saw the first sustained dengue outbreak in central Italy…

DR RORY GIBB

So my name is Rory Gibb. I am a senior research fellow here at UCL. So I’m based in the Department of Genetics, Evolution and Environment. 

And my background is as an ecologist, right? So ultimately I’m interested in what determines where species are and how they interact and how they interact with people and what that ultimately means for us. 

So more specifically, I work on infectious disease. So the bulk of my work focuses on really this question about how do climate and ecological processes and social processes interact to determine how sick people get, where people get sick and why. 

And I guess the value of a kind of an ecological perspective on this is that the vast majority of human diseases either have their origins in non-human animals or currently spill over to us predominantly from non-human animals. 

So that’s like everything from rodents and bats to sort of mosquitoes and ticks, right? These are really important kind of key species within the sort of diseases that we really care about and in order to actually understand, you know, who’s most at risk, why diseases cluster in certain populations. 

We need not only to attend to little sort of social factors but also to the kind of ecosystem level and the climatic processes that give rise to patterns of disease. So I kind of take a data science-based approach to this. 

I pull together, tend to pull together lots of data from different sources about kind of human health, about the climate and about sort of biodiversity and ecosystems and bring those together to try and ask questions about, you know, about what these processes are and, you know, whether we can understand and predict who’s getting sick and why. 

PROFESSOR PHILIP SCHOFIELD

It sounds incredibly complex… and you’ve also got an interest in the way climate change is affecting these processes, and might become more prevalent. Is that correct? 

DR RORY GIBB

Yeah, so I think a good way of, maybe a good way into this is actually mosquito-borne diseases, which I work on a lot. 

So the classic example of a really important human disease is malaria. Another really important emerging disease that I work on a lot is dengue. These are sort of two infections that are transmitted by mosquitoes, so these sort of tiny creatures that cause an absolutely huge burden on human health. 

The thing about mosquitoes is that they’re invertebrates, their body temperature is very much coupled to the temperature of the environment around them, and so as temperatures warm up we have, you know, more mosquitoes, their biological processes go faster, and you end up with basically the transmission of the pathogens that they carry changing depending on the climatic conditions. 

PROFESSOR PHILIP SCHOFIELD

So it’s not the mosquitoes themselves that are the problem, it’s the sort of the bugs that are, you know, parasitic on the mosquitoes. Is that correct? 

DR RORY GIBB

Yeah, I mean, so I think probably the best way to kind of understand what’s happening with mosquito-borne diseases is that there are sort of two things that are going on with the climate. 

One is that the climate very much restricts where those mosquitoes that we care about can be, right? So we can think of sort of dengue, for example, as being very much a disease of the tropics and subtropics, and that’s effectively to do with the fact that the climate is very suitable in those areas for those mosquitoes to live and transmit those infections. 

As the climate warms, there are large areas of the globe that are now becoming suitable for those mosquitoes that weren’t suitable before, and so what we’re seeing is then those mosquito species are moving around the planet, they are emerging and establishing populations in new places, and the pathogens are following. 

So, you know, a great example of this is something like the emergence of dengue fever in Italy, where, you know, just a decade ago we were seeing… You know, a few cases here and there, and then just last year we saw the first, you know sustained dengue outbreak that was able to continue transmitting over the course of a whole summer in central, Italy.

So that’s one piece of the process, right, mosquitoes are moving around and they’re taking their pathogens with them.

Another piece of the process is that in areas where the diseases are already a problem changes in the climate are reshaping the populations of those mosquitoes and how they’re behaving and how the pathogens are behaving within the mosquitoes, so an increasing frequency of climate extremes. 

So we’re seeing more extreme rainfall and extreme flooding events and also more extreme drought events that’s sort of changing the size of the mosquito populations at different times of the year and leading potentially to really big and really severe unexpected outbreaks that are happening. So we’re sort of seeing these these two pieces. 

There’s like a geographic expansion, diseases going to new places, and then there’s like an intensification where we have diseases becoming worse in places where they’re already a problem. 

PROFESSOR PHILIP SCHOFIELD

Right, how big a problem is dengue fever? 

DR RORY GIBB

So dengue’s becoming a massive problem for a few reasons. It’s an interesting disease because on the surface of it the fatality rate is not that high, right, so you know it’s sort of under well under one percent and so this year in the last year we’ve seen an absolutely unprecedented epidemic of dengue in Brazil. 

We’re talking several times higher than has ever been seen over the course of a dengue season. The number of deaths that have you know the number of deaths that have resulted from that many millions of cases is still relatively low compared to some other pathogens but there are a couple of things that make this really tricky. 

One is that dengue is really physically debilitating so if you get sick you’re pretty much unable to to work, like, you know, for potentially an extended period of time while you recover. So the economic costs can be really high and they can be especially high because of the fact that the populations that are sort of disproportionately affected tend to be poorer, marginalized, sort of people who live often on the urban peripheries of big cities, right, and so you can imagine that if you are and this is where the kind of climate justice angle comes in, right, you can imagine that if you are in one of those communities where you’re potentially relying on your work and then you know you become sick and you’re not able to work for several weeks that can really be a huge problem. 

So it has that kind of issue. The other challenge with dengue is that there are four main circulating strains of the virus that sort of circulate the planet. If you get infected by one and then recover you’ve got some immunity, you’ve got immunity to that one forever but if you get infected by another one, another one of the strains, you’ve got a much higher likelihood of severe disease and death. 

So there’s some really interesting kind of complexities around the virulence of the pathogens, how often you get infected, and as the climate is warming and the viruses are moving around the planet more and more, the opportunities for people to get reinfected again and again are increasing. 

So it’s sort of a changing landscape that’s both kind of economically problematic, but also increasingly sort of posing complex health risks. 

PROFESSOR PHILIP SCHOFIELD

Are there effective vaccines? Of course, if there are, they have to be affordable. 

DR RORY GIBB

Yeah, so precisely because of that interaction that I talked about, of the immune system with different dengue strains, there was one previous dengue vaccination that was rolled out and then actually was, there was a kind of rollback from that because of the fact that it turned out that if you hadn’t been infected with dengue before, it kind of mimicked the effect of a prior dengue infection, which meant that you may have been more likely to get severe disease after you were vaccinated. 

So this created some real challenges. So there’s a new generation of dengue vaccines that are coming through and the sort of, I think the Holy Grail is developing what they call a tetravalent vaccine, right? 

Which is where you have one that protects you against all four of these strains. But that’s very much kind of a work in progress. There are other really interesting sort of solutions that people are coming up with. 

And as an ecologist, you know, I’m sort of always interested in, you know, what those kind of more holistic solutions are as well, right? Rather than the kind of just the targeted kind of medical solutions. 

And one is something called Wolbachia, which is a bacterial pathogen of mosquitoes, which makes the mosquito much less likely to transmit the virus. So they’ve been releasing batches of mosquitoes that are infected with this bacterium. 

And then those populations outcompete the populations that already live there and massively suppress transmission. And some of the trials of that have been really effective. So I think it’s like, it’s a multi-pronged attack, right? 

We need to think about how do you change urban landscapes in ways that they are less amenable to the mosquito living there? How do we reduce people’s exposure to mosquitoes? But then what are these both ecological and also kind of medical interventions that we can come up with? 

PROFESSOR PHILIP SCHOFIELD

I mean, given that one of your interests is biodiversity, I mean, mosquitoes are part of the biodiversity of the planet. On the other hand, one might think, well, we’re better off without them. 

DR RORY GIBB

Yeah, so this is a question that I’ve thought about a lot. 

I guess there’s a couple of ways of sort of getting at that. One is that there aren’t that many medically relevant mosquito species compared to the sheer number of mosquito species that are already there. 

So if you were to try and remove a certain subset of mosquito species, that’s only a relatively small subset of mosquito diversity as a whole, right? So maybe you don’t lose those other important ecosystem kind of functions that mosquitoes help to support, right? 

They’re important food for bats, as one example, or for other sort of insectivores, right? So they are part of that. Yeah, if you kind of knock a species out of an ecosystem entirely, we often see unintended consequences, right? 

And I think one of the really interesting questions here is like, what might the unintended consequences be of mosquito eradication? I think we don’t maybe have a good handle on that as a whole. And certainly with something like malaria, where there’s sort of work looking to locally eradicate the major malaria vectors, for example, in parts of Africa, there’s always the question about what will come in to replace them, right? You know, what would come and fill in that gap in the ecosystem that that mosquito was previously filling? And could that pose its own problems? 

PROFESSOR PHILIP SCHOFIELD

What about eradicating the viruses that they carry? I mean, I’m thinking about this from from Bentham’s point of view, who says that, you know, all that matters is pain and pleasure. And insofar as an entity can’t feel pain or pleasure. It doesn’t matter. 

What viruses do, though, seems to be to cause lots of pain but, at least these viruses, don’t do any good. I mean, is there an argument that says, well, the world would be better if these things just simply didn’t exist? 

DR RORY GIBB

I think… I think that’s true. I think one of the questions is the logistical challenge of achieving it when we’re looking at viruses that transmit not only within the human life populations, right? So, you know, I guess the great example of an eradication effort that was really successful was smallpox right and smallpox was a human-only pathogen and when you were protected against smallpox through vaccination you have lifelong protection it proved to be very amenable to eradication right. 

One of the things that’s I think really for me as a biologist like really interesting but sort of really complex from a health perspective is a lot of these viruses that we are concerned about are freely circulating within wildlife populations right and we only ever see them when they spill over from wildlife populations into humans right. 

So there’s sort of a continually evolving pool of viruses in nature right some of which we get exposed to and are a problem many of which humans are exposed to and never really cause very much disease or perhaps someone gets a bit sick and then they recover. 

So the question then is how, you know, how might you go about eradicating those viruses within the wildlife population, right? On the one hand, you could attempt it, so there’s some quite interesting work being done by sort of colleagues elsewhere on you know what a transmissible vaccine might look like, you know, could you basically try and develop a vaccine for rodents, say, to vaccinate them against lassa fever ,which is a virus that I work on quite a lot and that actually spreads through the population and sort of helps to kind of vaccinate the whole rodent population and drive the virus out that way?

There’s the kind of other piece of this picture which is, you know, do we instead focus on what that human wildlife contact point is, right? And how do we sort of set at the link, you know, if we say it’s going to be logistically and conceptually really challenging to figure out how to eradicate whole kind of clusters of viruses from nature that are continually evolving, how do we make sure that people are no longer vulnerable to those or exposed to those, right? And I think that sort of to the Bentham point, like I think historically in ecology, which is where, you know, kind of I’ve sort of come from, a lot of the conversations have focused a lot on, you know, ecological interventions, right? 

You know, how might we intervene in ecosystems by changing landscapes, trying to protect biodiversity, trying to regulate against sort of, say, the hunting of wild animals in ways that sort of might reduce those hazards in nature, right? And there hasn’t been as much attention maybe paid to the question of what are the, you know, what are the social factors as well that we can bring into play here that can kind of help to reduce those risks? So, it’s like, can we do both, right? 

PROFESSOR PHILIP SCHOFIELD

Yeah, no, but Bentham was inoculated against smallpox when he was quite young. But do viruses then do any good? 

DR RORY GIBB

So, to put my ecologist hat on, it’s easy from our perspective to see parasitic microorganisms, right, be they viruses or bacteria or whatever, as problems, but they play really, really important roles in ecosystems, right? They help to regulate populations of species. They help to keep everything in balance, right? 

And if you, as you say, imagine sort of trying to eradicate microorganisms from the picture, you lose a really important level of ecological functionality that helps the kind of natural systems that we have to sustain themselves and also to sustain the benefits that they provide to people, right? 

Just as one example through kind of regulating the populations of pest species, like that might just be kind of one tangible example, you know, a disease of rodents that kind of helps keep their population in check if it gets too big, right? 

So yes, if you start to remove, if you were to remove the entire diversity of microorganisms from nature, I think you lose a huge amount of functionality, right? If you were to focus on just those medically relevant viruses, maybe not so much, right? 

I mean, I think it probably really depends on the context. So I think removing viruses as a whole is sort of both impractical and sort of not necessarily desirable since so many of them do not cause major issues for us. 

But I think asking the question of what are those viruses that are most important medically that circulate within wildlife can we identify those wildlife populations that are likely to host them? Can we figure out who is most at risk? 

And then ask about, you know, what are the targeted ways that we can sort of address the problem, bearing in mind those kind of local contexts is probably the way forward, I think. 

PROFESSOR PHILIP SCHOFIELD

That’s interesting. And how long will it be before dengue comes to Britain? 

DR RORY GIBB

So the question of when dengue fever would come to the UK is quite an interesting one. I think the answer is probably not super soon, for two reasons. 

Firstly, because we are quite a lot cooler at the moment than the mosquitoes that our major dengue transmitters like, and also that the virus likes for for effectively infecting the mosquitoes. And the second reason is that we actually don’t have dengue vector mosquitoes living here yet. 

However, they are marching northward through Europe, right? So, you know, Aedes albopictus, which is the main kind of dengue vector in Europe, is now in the – we are seeing dengue outbreaks occurring in Montpellier. 

So, you know, there are it’s it’s kind of working its way up. We do have a different climate, right, the continental climate. And I think that does create something of a buffer. And a lot of the prediction studies have suggested we’re looking at late this century, as opposed to in the next few years. However, if we look at what’s been happening with the climate in the last decade and a half or so, I think everything has moved a lot faster than we had anticipated, right? 

And so I think a lot of the work that, for example, the UK Health Security Agency are doing the vector teams there do a lot of work on monitoring mosquitoes along the M2, right, coming up through through Kent, because they often travel through shipping routes and travel and trade. 

And so trying to detect those those problematic species when they emerge and prevent them from establishing here. There are other vector-borne diseases that I think we should be concerned about more immediately. 

So there’s another disease called West Nile fever, which is hosted by by birds. So that’s those are the species that it naturally transmits within. But it’s transmitted by mosquitoes. The main mosquito that transmits it we have here is one of our most abundant mosquitoes. 

And as the climate’s warming, West Nile has been working its way up through Europe and becoming more and more of a problem. I think it’s much more likely that West Nile virus will arrive here before Dengue and will probably arrive in the next sort of 20 years, maybe less. 

And that causes a range of disease severities from kind of mild or relatively asymptomatic all the way up to encephalitis – brain inflammation. So it’s sort of… it’s a pretty nasty infection. And I think that that’s something that we are expecting to see, I would say, in the UK earlier than Dengue. 

Again, the sort of predictive studies around when this is likely to happen are suggesting sort of 2050 plus. I think there are a bunch of reasons to think that those sorts of big scale prediction studies don’t always get it. 

And so I think a lot of the work that is starting to happen here now by various teams in the UK is focused on that question of, like, what happens if it gets here sooner and how should we be doing surveillance? 

Like, you know, how should we be trapping mosquitoes and looking at birds? What should we be monitoring to try and make sure that when some of these pathogens arrive that we can detect them quickly? 

PROFESSOR PHILIP SCHOFIELD

And again, is a vaccine a possible? 

DR RORY GIBB

Yeah, I actually don’t know that. I mean, I suspect that a vaccine would be a solution for West Nile disease. I actually don’t know much about West Nile vaccination and the success of any vaccine candidates. 

It’s become a really big problem in the U.S. after it arrived there in about 1998, 99. So I suspect that it’s being very actively worked on. 

So the development of vaccines for emerging diseases, emerging zoonotic diseases, so that’s what we call diseases that transmit from wildlife to people, has a really, there’s challenging dimensions to it, right? In that, historically, it just hasn’t been prioritized by pharmaceutical companies, right? It hasn’t historically been perceived to be a particularly profit-making endeavor compared to working on therapeutics for non-communicable disease. 

This has been a consistent problem for vaccine development overall, but it’s particularly been a problem for emerging diseases, like things that we might want to prepare for that aren’t sort of to the scale of some of the very large infectious diseases, the big infectious diseases that infect humans. 

Since around 2014, when there was a very large Ebola epidemic in West Africa, that everyone was extremely underprepared for, and it was very badly managed, and a lot of people died, there’s been a concerted push by a lot of international, governmental, and non-governmental organizations to try and sort of push emerging diseases more into that agenda, and also to accelerate vaccine development. 

So there are a couple of organizations that are really involved in that. There’s one called CEPI, who I’ve done some work with. They’re an NGO that’s funded by governments and philanthropy and others to effectively accelerate the development of these sorts of vaccines in university settings mostly, right? 

So they are mostly being developed by academic teams, and then they are funding the development of candidate vaccines, and then they’re funding their trials, and they’re sort of funding their rollout, and they’re also funding research into how best they should be deployed, which is some of the work that I’ve done with CEPI before. 

PROFESSOR PHILIP SCHOFIELD

I mean, did the COVID outbreak give a boost or an encouragement to the vaccine production industry? 

DR RORY GIBB

So on one level, I think the COVID pandemic really emphasized from a sort of global health and economic kind of policy perspective, like how destabilizing a pandemic of a novel wildlife born infectious disease can be, right? And I think that has sort of intensified the importance and sort of the funding landscape for funding the development of new vaccines and that includes through an organization like CEPI. 

How long that effect will last for? It’s hard to know, right? So we’re a few years out from the pandemic now and there’s a whole other series of kind of political and geopolitical social concerns that have sort of overtaken our discussions about pandemic risk again, right? 

And so I think it’s an open question how long, you know, the sort of that heightened sensitivity will last. I think it’s already fading in some senses and a lot of people who work in this area either from a research perspective or a sort of policy perspective, I’d say including myself on the research side are concerned about how we keep this in the, you know, in the conversation, right? 

And that includes for vaccine development, but it includes for sort of pandemic preparedness more broadly, as well as for kind of fundamental ecological work to understand, you know, as I’ve talked about, these relationships between, like, biodiversity and ecosystems, the species that carry diseases we care about and then where and when those infections might emerge in people. 

DR RORY GIBB

I’ve got to ask you this, do you think the COVID virus came from an animal or from a laboratory? 

PROFESSOR PHILIP SCHOFIELD

I think the overwhelming weight of evidence supports a wild animal, not a laboratory origin. Markets in the wildlife trade and wild animal farming are definitely one important conduit right of viruses from nature to people. 

I mean, I guess that’s evidenced by the fact that both SARS, coronavirus, epidemics, firstly SARS-1 in 2002 and then SARS-2, COVID in 2019 onwards, both emerged through that route, right? So, it’s definitely something we should be concerned about in many ways these sorts of spaces create a kind of incubator for pathogens to transmit between species, right? 

If you’ve got stressed populations of wild animals that are kept in close proximity to one another you are creating a kind of incubator condition. I would say that that is far from the only thing that we should be concerned about and I think it’s more about what are the other processes by which kind of pandemic or epidemic diseases emerge right. 

So another really important factor driving these things is agriculture, so sort of industrial agriculture and the important example for that is influenza viruses right which sort of circulate and diversify within intensive poultry populations and that’s given rise to various highly pathogenic avian influenza strains which then spill back into wild birds and are now circulating the planet right so that’s not the sort of sole concern. 

I would say it’s a – and this is going back to my point, I guess, that different diseases have really different characteristics. They’re carried by different species. The species that carry them respond differently to the same sets of human pressures. And so, you know, if we want to understand or kind of anticipate what’s going to emerge from where we need a better understanding of what those sort of ecological conditions are that support different kinds of diseases so we can anticipate. 

PROFESSOR PHILIP SCHOFIELD

Yeah, what sort of, let’s say, reforms would ideally you introduce? 

DR RORY GIBB

Right, so I think we’re clearly in a position now, right, where mitigation of fossil fuel emissions and of climate change as a phenomenon is a massively important global public health intervention for this century, right? 

Not only because of infectious disease, but because of all of the other downstream consequences for health that emerge from. climate getting warmer and a higher frequency of climate extremes and losses of crop production and all of those kind of consequences that we’re seeing. 

So at the very big scale there are these big drivers that we can think about levers to address. One is fossil fuel and other greenhouse gas emissions and the other is biodiversity loss, so erosion and change of ecosystems and the species that live in them. 

And that’s for the reason that ecosystems don’t only regulate infectious disease, they do a whole lot of other things that we rely on as well. So they provide us with better regulation of the climate through sort of forest growth and the locking away of carbon and they provide us with pollination for food crops and regulation of pests and all of the other things that we need in order to sort of sustain our lives. 

And so there’s an argument that in a lot of ways pulling those big levers is incredibly important and that’s effectively like a mitigation of the damage that’s being done question. I think from the perspective of infectious disease those are big levers to pull and I think that you know they will have positive consequences for a lot of diseases but not necessarily for all of them because different systems are complex. 

So I think there’s a lot more to be done on the social side to adapt to changing patterns of risk. So that’s really thinking about how do we ensure that people and that’s disproportionately kind of marginalized communities in marginalized parts of the world are not being disproportionately exposed and made vulnerable to these pathogens as they emerge. 

And so part of that is sort of large-scale economic change, ultimately transformational economic change about how the economic and exploitative dynamics of the planet currently operate. 

But more locally, thinking about not necessarily checking urbanization so much as how do we ensure that the people who are living in rapidly expanding cities have access to the right sort of housing and sanitation infrastructure that those sorts of, that creating healthy environments is supported for everybody. 

And then also ensuring that people have access to health systems that people can get access to medical care when they need it free at the point of use and access to diagnostics and therapeutics and vaccines for these infections. 

I think in many ways, given the ecological complexity, one of the strongest arguments, and this has come out of some work that I’ve done recently, is that we should prioritize health systems strengthening globally as, like, a key, sort of key intervention against a whole series of disease threats that are shaped by ecosystems in parallel or kind of in tandem with those sort of big kind of levers that we should pull on the ecological and climate side? That was quite a long answer… 

PROFESSOR PHILIP SCHOFIELD 

No, thank you very much indeed, really interesting. 

DR RORY GIBB

Great. Well, thank you guys.