Human beings are responsible for the emergence of new viruses

With the spread of Covid-19 around the world, a question is mobilizing more and more researchers. Is that'emergence infectious disease may be linked to anthropogenic environmental change? The answer seems to be positive. The promiscuity between humans and animals is a known factor that promotes the risk of zoonosis. And a new study published in Proceedings of the Royal Society Balso abounds in this direction.

Led by researchers from the university's veterinary school UC Davis in California she links the risk of seeing a virus moving from animals to humans and our interactions with them.

Livestock and those threatened by humans harbor many zoonotic viruses

Scientists analyzed 142 identified zoonotic viruses and terrestrial mammals that can be potential hosts. By crossing the data with the list of cash Endangered by the IUCN (International Union for Conservation of Nature), they also took into account the size of the population for each species, its state of conservation and the risks of extinction that it runs. They drew several important conclusions.

Domestic and farm animals are the ones that share the most viruses with humanity. They carry eight times more zoonotic viruses than wild mammals. This is not a surprise, since Man has had close relationships with these species for a very long time.

In a second time, the wild animals, but which have adapted perfectly to humans, also harbor zoonotic viruses. The species analyzed include certain rodents, monkeys, which in certain regions thrive in the city, and bats which sometimes live on farms or in granaries. If humans have less direct contact with these species, they can still be the cause of zoonoses.

Finally, among wild animals, those which are in danger of extinction are the most predisposed to harbor zoonotic viruses. The species that are hunted, poached or threatened by habitat destruction harbor twice as many zoonotic viruses as species threatened by factors independent of human activity.

Rethinking our interactions with wildlife

These results highlight how anthropogenic activities, often harmful to the environment and animals, can threaten the health of all humanity. The Covid-19 pandemic, but also sras or the H1N1 flu, they were all caused by zoonotic viruses and have spread widely around the world, killing many people.

" Obviously, we no longer want a pandemic of this magnitude. We need to find a way to safely coexist with wildlife, as there is no shortage of viruses to transmit to us Explains Catherine K. Johnson, first author of the study and research director of the USAID PREDICT project at the university veterinary school UC Davis.

The destruction of natural habitats promotes the emergence of new epidemics such as Covid-19

Article published on March 29, 2023 by Julie Kern

Emerging zoonoses, such as Covid-19, have been around for a long time and are expected to multiply in the coming years. According to scientists, human activities and their impact on ecosystems formerly preserved are the cause.

Ebola, Covid-19, the AIDS, all these viral diseases thrived in animals before crossing the species barrier, sometimes several times, and infecting humans. Regularly, zoonoses have emerged from " hotspots »Of biodiversity. A decade ago, we thought that the tropical forests virgin and intact posed a threat to human health because of all the species exotic who lived there.

But recent research proves just the opposite. It is the alteration of ecosystems by human activity that makes " hotspots Of dangerous biodiversity, not just their presence. The construction of roads through the rainforest or even the splitting of ecosystems to install cities or fields there create the ideal conditions for the emergence of new diseases like Covid-19. And it is not about to stop.

65% of emerging diseases come from animals

According to a 2014 study led by Kate Jones, Chair ofecology and biodiversity atUniversity College in London, 65% of emerging diseases identified between 1980 and 2013 were zoonoses. An increasing figure over the 33 years spent under scrutiny in the study. Countless viruses pathogens have always evolved in animals, but humans now come into contact with species they would never have encountered otherwise. We ourselves create the conditions favorable to the emergence of zoonosis, by investing in more and more remote places or by being rubbed shoulders with exotic species on bushmeat markets, as there are in Asia or in Africa.

" There is a misunderstanding among scientists and the public that natural ecosystems are a source of threat to us. Nature contains threats, it is true, but it is human activities that cause damage. The health risk in a natural environment can be aggravated when one interferes with "Explains Richard Osfeld, emeritus scientist at Cary Institute of Ecosystem Studies in New York in an article appeared on the site Ensia.

Can we prevent the spread of future diseases?

In addition, with wild animal species suffering from the scarcity of their habitat, their population decreases or they simply disappear, and viruses too. By losing their host natural, they seek a new one to infect, and Man is a host of choice. Once the virus has crossed the species barrier and has adapted to the human organism, our modern, dense and ultra-smart health connected societies are ideal for the spread of a virus. The Covid-19 will surely not be the last zoonosis to threaten human health.

What can we do ? Definitely close the bush markets which constitute homes potential for a new zoonosis? It is hardly imaginable, they provide food to millions of people. According to Kate Jones, " We need to think about global biosecurity, find weaknesses and strengthen health systems in developing countries. Otherwise, we can hope to relive the same scenario "