Emerging viruses: “We must preserve the habitat of animals and avoid coming into contact with them too often”

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The emergence of new diseases within the animal species is not without consequences for humans. With increasingly frequent contact and international exchanges, humans today are exposed to viruses that can trigger epidemics.

The images had gone around the world. Captured from the sky, they showed miles and square miles of trees going up in smoke. Entire parts of the Amazon, the largest forest in the world, reduced to ashes. This is the result of a policy led by the far-right Brazilian president, Jair Bolsonaro: in the South American country, deforestation increased by almost 22% between August 2020 and July 2021, according to data published in end of last year.

But such operations do not only mean the massive felling of trees, they also cause the disappearance of the habitat of many animal species. A destruction that is not without consequence, as explained by Muriel Vayssier-Taussat, head of the animal health department at Inrae: “Destroying the natural habitat of animals upsets the balance. This changes the behavior of these species which very often have to changing environment to survive”.

The specialist takes the example of the Nipah virus which emerged in Malaysia. There, major deforestation operations were taking place to develop agriculture. However, in these forests lived bats. With the destruction of their natural habitat, these animals had to move closer to human habitations or farms to find their food. It was there that they were in contact with pig farms to which they transmitted the virus which then reached humans…

Greater diffusion capacity

“All animal or human species carry bacteria, viruses or parasites which are not necessarily dangerous for the living being that carries them, but it is when these microbes are transmitted to other species that they can become pathogenic or dangerous”, explains Muriel Vayssier-Taussat. This seems to be particularly the case with a now well-known virus: Sars-Cov-2. “We do not currently have certainty about the exact origin of this epidemic, but one of the hypotheses evokes a transmission of the virus from bats to humans.”

The microbiologist adds that there have always been epidemics, but with globalization and increased exchanges, they now have a greater capacity to spread. “In the 20th century, with the discoveries of antibiotics, the development of vaccination and hygiene measures, we believed that we could protect ourselves from these emerging diseases, but we can clearly see that this is not the case. and the evolution of human activities, in particular the development of transport, makes their propagation much easier today.

“Ultimately, everything is a question of balance, she says, we must preserve the habitat of animals and avoid entering into contracts with them too often by preserving the biodiversity of ecosystems. But this remains complicated because epidemics do not all have the same origin, so to protect ourselves from new epidemics it is necessary to study the factors which are at their origin, to understand them in order to act on these factors and limit their effects. This is precisely the purpose of the Prézode international research program launched in 2021 with the aim of preventing future pandemics.

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