Understanding pathogens and parasites – and the future of the planet
- UdeMNouvelles
01/15/2025
- Jeff Heinrich
We are facing three concurrent existential crises: biodiversity loss, planetary change, and emerging infectious diseases. We cannot look for a non-existent, one-size-fits-all solution.
Credit: Getty
It’s time to get a better read on how infectious diseases are tied to the loss of biodiversity worldwide, an international team of scientists argue in a new paper.
It’s all connected: coronaviruses and other emerging infectious diseases, loss of biodiversity, and destruction of the environment by humans. Around the world, pathogens and parasites are responding to the changes in unexpected ways, fueling the rise of pandemics and the extinction of countless plant and animal species.
But all is not lost. To stave off disaster, scientists must focus on monitoring and limiting the spread of a handful of high-risk viruses, especially on farms and in live-animal markets, and governments must step up efforts to track pathogens, protect wildlife and strengthen public-health systems, Canadian and American experts argue in a new paper.
Led by computational ecologist Timothée Poisot, an associate professor of biology at Université de Montréal, and Colin J. Carlson, an assistant professor of epidemiology at Yale University’s School of Public Health, the research by scientists in Canada, the United Kingdom, U.S. and China is published today in the inaugural issue of Nature Reviews in Biodiversity.
As well as providing an overview of current science, the scientists offer a historical perspective on global pandemics and the spillover events (viral, bacterial and others) that have occurred since 1960. They then make several recommendations, particularly on preventing future pandemics, and more broadly on improving surveillance techniques in public health.
We asked Poisot, whose co-authors include Cole Brookson, a member of Carlson’s lab and guest researcher in Poisot’s lab at UdeM, to tell us more about the report and its implication for future policy.
First of all, how comprehensive is this study – and is it a first?
Ecologists have been trying to understand how biodiversity and disease are related for well over a century now, so it is difficult to claim to be the first. But we have tried to make this study very comprehensive. The COVID-19 pandemic has led many ecologists to think about infectious disease, and we wanted to provide a strong, contemporary roadmap to the state of knowledge. One thing we bring with this article is a strong emphasis on action and solutions: how can we use initiatives like the Kunming-Montreal Global Biodiversity Framework, or the UN Convention on International Trade in Endangered Species, as a scaffold to think about efficient management of infectious-disease risk? This is one of my favourite outcomes of this study: not only can we provide a good overview of current knowledge, we can also identify work to do on policy and governance. It’s a very action-oriented review of the scientific literature.
How data-driven are your efforts?
We re-analyzed a lot of existing data, both to provide a clear historical picture of where pandemics started, where we had observed more reports of infectious-disease emergence, and where we know we are still far from a clear picture of viral diversity. For example, we don’t know which viruses can infect the vast majority of aquatic mammals in the Southern hemisphere. More than 1,500 species of rodents, and about 1,000 species of bats, have no documented viruses at all. This is important information for biodiversity scientists: there is a whole world of viral diversity that needs to be documented urgently, and this work will have tangible benefits for disease prevention.
You point out that almost all infectious diseases in human originate in animals – from wildlife, from livestock, even from pets. How do you see this evolving?
The reason why most of our diseases originate in animals is that this situation has been evolving for as long as there have been animals – so, for about 800 million years. This is a lot of time for viruses to adapt to things we have in common: the receptors in our cells, our immune systems, our physiology. But we also spend a lot of time near animals – by keeping them as pets or as livestock, by using them as food, and by disrupting their habitats. Every time two species come in contact, they have a chance to share their viruses. Because humans are widespread, and very efficient at transforming our surroundings – often for the worse – we come into contact with a lot of other species. This is unlikely to change, but we can absolutely make our contacts with other species safer. If we know that deforestation can directly increase the global burden of disease, can we think about alternatives for economic growth? If we know that industrial farming creates more possible chains of transmission of disease, can we introduce incentives to have more sustainable practices? But the transmission of disease remains a natural, unavoidable phenomenon: we also need to ensure that we invest enough in surveillance, and that we share vaccines, drugs and other countermeasures equitably. Even if we get better at preventing the spillover of diseases, we still need to be prepared for when it happens.
Overcultivation and the overall warming of the planet have combined to drive the spread of disease. How will a ‘One Health’ approach help turn the tide?
On paper, the One Health approach seems ideal to address these challenges. In a nutshell, by recognizing that the health of people, animals, plants and nature are connected, we can formulate win-win solutions. But there are a couple of major hurdles to clear before this. First, we don’t really know how to operationalize One Health: what does it means to “do One Health” in the real world at such a scale? Looking back, the scientific and policy community has been able to make impressive progress without this concept. Second, One Health is expensive, currently estimated at 20 to 30 billion dollars U.S. a year. Who will pay for this? Are we sure that it will be more effective than the current approaches? The Pandemic agreement that member states of the World Health Organization are currently writing is stuck in part because there is no international consensus on One Health – this is frightening! It’s an important and elegant way to look at health, sure, but it’s nowhere near important enough to jeopardize one of the most important policy instruments we will see in our lifetimes. This is one thing we wanted to emphasize with this study: being dogmatic doesn’t help. We are facing three concurrent existential crises: biodiversity loss, planetary change, and emerging infectious diseases. We cannot look for a non-existent, one-size-fits-all solution.
About this study
''Pathogens and planetary change'' by Timothée Poisot et al., is published in Nature Reviews Biodiversity.
