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Serge Morand: “When we lose biodiversity, we lose the regulation of epidemics”

Unless we address climate issues seriously, Covid-19 will not be the last pandemic humanity will have to face. While the exact causes of the emergence of this pandemic remain mysterious, there is little doubt that it is linked to environmental imbalances.

Ecological pioneer Serge Morand is currently a research director at the French National Centre for Scientific Research (CNRS) and an associate researcher at the French Agricultural Research Centre for International Development (CIRAD). His research focuses on the study of ecological and biological theories to understand human health and the emergence of diseases. He recently appeared in Making Pandemics, the investigative journalist Marie-Monique Robin's latest documentary. On the occasion of a special premiere at UNESCO headquarters in Paris on April 22, Morand shared his observations on these issues.
Sege

Interview by Mila Ibrahimova 

What is the link between biodiversity and the emergence of infectious diseases? Can you explain what the “dilution effect” is?

When we study biodiversity, we look at pathogens too, and at microbes. So there is quite a clear link between the diversity of infectious disease and the biodiversity of wildlife, including vectors and reservoirs. Considering biodiversity at threat, when one starts to look at the decrease of biodiversity, there is actually a correlation between the outbreaks of infectious disease and the clustering of epidemics. In other words, every time a country experiences biodiversity loss, there is an increase in the number of epidemics of infectious disease on our planet. Biodiversity loss includes a decrease in the diversity of species but also, and this is an important function of biodiversity, in the interactions between species. So when we lose biodiversity, we find ourselves with less predators – the big predators or the small predators which could reduce the reservoirs or control the vectors (the arthropods, the mosquitoes, the ticks). This means that we are losing the “specialist” species, the ones that can regulate the “generalist” species which tend to thrive in human-dominated habitats. And this last category starts to spread. Good reservoirs, such as rats, can then increase in density, because they aren’t regulated by predators, and subsequently amplify the amount of pathogens. These pathogens can spillover and contaminate the livestock or humans, so that is when there can be an emergence of epidemics. In short, the “dilution effect” means that when we lose biodiversity, we lose the regulation of epidemics.

This isn’t just an “epidemic of epidemics”, but it should rather be called an “epidemic of pandemics”. 
Serge Morand

What is the expression “epidemic of pandemics” about, and how can we change its course? 

This is also something that is a pattern. I have been studying all the infectious diseases which are linked with humans (vector-borne and zoonotic diseases), and those linked with livestock or poultry, as well as the diseases of wildlife. The data collected by WHO, FAO or OIE (World Organization for Animal Health) shows an increase in the number of epidemics through time. So it does look like there is an “epidemic of epidemics”. When one wishes to study this pattern in further detail however, one must bear in mind that we have increased the movement of humans, animals, plants – everything on the planet. From then, one may suppose that the data on epidemics may be somewhat related to the boom in international trade and international travels. Before the 1960s when there was an epidemic, most diseases stayed in one country, spread to a few close countries or sometimes, through trade; most of them remained very localized. But from around 1962, statistics show that more and more of these diseases started to spread. And nowadays, it’s very clear that when there is an epidemic of an infectious disease somewhere on the planet, it is likely to spread very soon all over the world, due to trade and movements of people. So this isn’t just an “epidemic of epidemics”, but it should rather be called an “epidemic of pandemics”. 

Do you feel that your voice is being heard? 

My colleagues and I have been working for years on the ecology of diseases, in relation to human health, animal health, wildlife health and even plant health. There aren’t that many of us though, and we have always felt a little isolated. There is this idea that by identifying new pathogens, we could improve what we call biosurveillance, or biosafety, and that we could be better prepared. I argue however that if we don't take an interest in the factors that explain epidemics, it will be practically impossible to foresee them. One thing the Covid-19 pandemic has shown us is that, despite all that we had done in terms of prevention, we were not prepared at all and we were, once again, taken by surprise. I think that this served as a real trigger on two levels, both local and international.

UNESCO has an enormous role to play in a better prevention of pandemics, based on culture, research, biodiversity and education.
Serge Morand

To what extent has the current pandemic redefined the way health issues are to be tackled at an international scale?

At the level of international organizations, there is a remobilization. I am thinking of the World Health Organization (WHO), the Food and Agriculture Organization (FAO), the World Organization for Animal Health (OIE) and the United Nations Environment Programs which have finally set up new arenas for discussion between scientists and international policies, especially on prevention. What’s more, they introduced the vision that not only are human health and animal health linked, but also the health of ecosystems. So we have reached a level we call "three healths" meaning that, simply put, ecologists are finally starting discussions with doctors and vets. The same goes for UNESCO, which understood quickly (from 2020) that it had an enormous role to play in a better prevention of pandemics, based on culture, research, biodiversity and education. UNESCO also has the Biosphere Reserve Programme; I co-organized a workshop about a month ago, on the construction of "One Health", which was financed by the European Union and in which an Algerian biosphere reserve was fully involved. Bear in mind that the first director of UNESCO, Julian Huxley, is one of the founders of the ecology of infectious diseases. So now, we have an international context that has never been so… I would say more than favorable, supportive, and demanding of action.