- Every Friday, 20 Minutes offers a personality to comment on a social phenomenon, in their "20 Minutes with ..." meeting.
- Make way this week for ecologist Philippe Grandcolas, director of research at the CNRS, who invites us to come back to the how and why of the outbreak of the coronavirus epidemic. A question too left under the radar so far.
- Whether the virus was transmitted to humans by pangolins or by bats, "this health crisis is indicative of the current state of biodiversity," says Philippe Grandcolas. More specifically, the way man mistreats her.
What does the coronavirus pandemic say about the state of our biodiversity? "The question has still been asked very little," regrets the ecologist and systematist Philippe Grandcolas.
Warm, while the battle is still raging against the virus, the discussions focus on the number of masks to deploy, screening and remedies after the crisis. "Very normal questions, concedes the research director at CNRS and director of the Institute of" Systematics, Evolution, Biodiversity "*. Nevertheless, to learn the right lessons from this epidemic, it will also be necessary to question how and why this epidemic was born, invites the scientist. Philippe Grandcolas answers questions from 20 Minutes.
"Nature sends us a message," said Nicolas Hulot, on BFMTV, about the coronavirus epidemic. Should we see, in fact, a revenge on nature?
These declarations that personify nature annoy me from a scientific point of view. The Ipbes [the equivalent of the IPCC, but for biodiversity] communicated in more or less the same terms. And yet nature, as an entity, does not exist. There are in fact organisms, individuals with all their interactors, micro-organisms, congeners, the physical environment ... All of this lives, evolves, develops, dies. There is no will of this system to take revenge on the human species. This idea that nature sends us a message takes us away from an essential question, very little asked since the beginning of the coronavirus epidemic: how and why did this epidemic arise?
What exactly is the origin of this pandemic?
Scientists are still at the hypothesis stage today. The most likely is that the pangolin [one of the species of wild animals sold at the seafood market in Wuhan] would have served as an intermediate host between bats and humans. We know that the virus that causes the current epidemic, SARS-CoV-2, is part of the genus Betacoronavirus. We also know that bat species naturally harbor a large number and variety of them. A team of Chinese scientists has succeeded in isolating a virus from pangolins whose genetic sequence is very similar to SARS-CoV-2. There would then have been, possibly, a genetic recombination between a pangolin virus and a bat virus. This natural phenomenon often happens and can have serious consequences. Here it would have enabled SARS-CoV-2 to acquire the capacity to enter human cells.
Again, this is just an assumption. There are hundreds of bat species and not all of their viruses have been screened. One of them may soon find a virus almost identical to that which is causing the current epidemic of coronavirus in humans. We could then deduce that the virus passed directly from bats to humans, without any help from the pangolin.
Whether it was transmitted by the pangolin or the bats, does that change much in the lessons to be learned in this epidemic?
Anyway, there remains in an epidemic linked to a zoonosis, that is to say a disease in which the reservoir of the infectious agent is an animal. Among these zoonoses, the majority comes from wild animals. Consequently, this epidemic of coronavirus is indicative of the current state of biodiversity. More specifically, the way man mistreats her.
How does one come to suspect the pangolin of being at the origin of the pandemic, when it is a rather solitary and nocturnal mammal which lives in the tropical forests of Asia and Africa southern? Theoretically, his contacts with humans are limited, and therefore the probability that he will transmit a virus to us is low. Except that the pangolin is one of the most poached species in the world. It is both sought after for its scales [prized by traditional Chinese medicine] and its meat, mainly consumed in China, Southeast Asia and Africa. This trafficking in exotic animals has two major consequences. On the one hand, it increases the risk of an epidemic by putting us in contact with rare infectious agents, this trade supplying markets present today in large urban centers. On the other hand, these traffics bring various animals into contact and allow infectious agents to recombine and thus be able to cross the barrier between species. This was the case for the previous SARS (previously). This also seems to be the case for the Covid-19.
The Covid-19 is just one example of these epidemics linked to the biodiversity crisis?
Of course. The error, coming out of this crisis, would be to say that there have always been epidemics, that they existed long before the biodiversity crisis. Indeed, we have been able to genetically trace diseases that are centuries old, even thousands of years old. Some have disappeared, others - like malaria, tuberculosis - no. What is clear today, however, is that the number of epidemics linked to zoonoses has increased in recent decades. Again, we can see signs of abused biodiversity. We are destroying the natural environment at an accelerated rate, we breed animals anyhow, we hunt exotic and wild species for foolishly recreational reasons. In doing so, we are simplifying the living world, allowing infectious agents to proliferate more easily. In a way, we are creating disease reactors.
Take the Ebola virus, which continues to regularly strike West and Central Africa. The problem is almost identical to that of the Covid-19. The reservoir of the infectious agent is bats. In forest systems very degraded by human activities, these bats find themselves much more easily in contact with humans. Promiscuity is high with the inhabitants of the surrounding villages and the probability of transmitting the virus is greater. Fifty years ago, the disease may have remained confined to these villages. Today, it can spread very quickly, these villages being connected to large urban centers.
How do you explain the fact that there is little awareness today of the danger posed by these zoonoses?
This remains relatively diffuse, including within the scientific community. The reason is undoubtedly that the biodiversity crisis is more complex to grasp than, for example, climate change and its consequences. Like the mega-bugs that hit Australia a few weeks ago. We have already released enough greenhouse gases into the atmosphere, and they will stay there long enough, so that the probability that Australia will experience new episodes of severe drought is very high, not to say certain. We must therefore expect new fires in this region in the coming years.
We also know that we will have to face future epidemics linked to zoonoses, but nobody can predict exactly when and where they will occur. Nor from which animal reservoir. Quite simply because many factors come into play: deforestation, poaching, international trade **, the directions we are taking to feed the planet (animal husbandry, etc.).
That China immediately and completely banned wildlife trade and consumption on February 24 is only a small part of the solution?
Yes. And neither should we fall into a kind of “North-South” controversy, where we would point only to the trade in wild animals or the farming of semi-wild animals practiced. All the more so because, for certain communities, it is a subsistence economy. On the other hand, this international trade in wild species also feeds on foolishly recreational reasons which must be questioned. The attraction of the rare, exotic meals, naive pharmacopoeias ... These are the first things to question.
But our European ecosystems are also mistreated. For example, we massacre foxes which nevertheless help to control the rodents involved in Lyme disease, another epidemic which also affects us closely. Intensive farming, including as it is done in Europe, is problematic. A large number of animals are kept in close proximity and, to prevent them from getting sick, they are constantly treated with antibiotics. In the long run, this can lead to the development of resistance in bacteria potentially pathogenic to humans.
This fight against antibiotic resistance is one of the three main objectives with the global initiative “One Health”, launched in the 2000s to better tackle emerging diseases at pandemic risk. The other two are to control zoonoses and ensure food safety. This initiative is particularly resonant today. In any case, it reminds us that we cannot live in a bunker where we would never be in contact with biodiversity. Killing all pangolins or all bats to guard against future pandemics would make no sense, especially since these species assume crucial roles elsewhere. The living world harbors a host of microbes that are essential here and there, including for us. You have to learn to manage risks. Quite simply, do not do anything with biodiversity.
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* A joint research unit of the National Museum of Natural History, the CNRS, the Pierre and Marie Curie University and the Practical School of Advanced Studies
** Zika or Dengue viruses are transmitted by exotic mosquitoes transported worldwide by humans through international trade, recalls Philippe Grandcolas in an article published in The Conversation.
- Animals
- Disease
- Virus
- Biodiversity
- epidemic
- Coronavirus