Sras, Mers, Ebola, avian flu, zika, Covid-19, HIV, monkey pox… Favored by our lifestyles, zoonoses, diseases transmitted to humans by animals, have multiplied in recent years, raising fears of the emergence of new pandemics.
“The interface between humans and animals has become quite unstable,” said Dr. Mike Ryan, head of emergencies at the World Health Organization (WHO), a few days ago. “Disease emergence and amplification factors have increased,” he said.
Monkeypox, latest example
We have just seen it with monkeypox, but not only, he warned. This monkey pox — “monkeypox” in English — caused by a virus transmitted to humans by infected animals — most often rodents — is the latest example of the multiplication of these zoonoses.
These are infectious diseases that vertebrate animals can transmit to humans. Some even end up becoming specifically human, like Covid-19. According to the World Organization for Animal Health, about 60% of emerging diseases are of zoonotic origin.
Appeared thousands of years ago, since man intensified his interactions with animals by domesticating them, they have seen their frequency greatly increase over the past twenty or thirty years.
Intensive breeding, travel…
In question, “the intensification of travel, which allows them to spread more quickly and in an uncontrolled manner”, underlined to AFP Marc Eloit, head of the Discovery of pathogens laboratory at the Institut Pasteur.
By occupying ever larger areas of the globe, man also contributes to disturb the ecosystem and promote the transmission of viruses.
Stepping up factory farms thus increases the risk of spreading pathogens between animals. Wildlife trade also increases human exposure to the germs they are likely to carry.
Deforestation and climate change
Deforestation reinforces, she, the risk of contact between wildlifepets and human populations.
“When we deforest, we reduce biodiversity; we are losing animals that naturally regulate viruses, which allows them to spread more easily,” Benjamin Roche, biologist at the Research Institute for Development (IRD), specialist in zoonoses, told AFP.
Climate change will also push many animals to flee their ecosystems for more livable lands., alerted a study published in Nature at the end of April. However, by mixing more, the species will transmit more of their viruses, which will promote the emergence of new diseases potentially transmissible to humans.
“We need improved surveillance in both urban and wild animals, so we can identify when a pathogen has jumped from one species to another,” said Gregory Albery, environmental health specialist at the Georgetown University in the United States and co-author of the study. “And if the recipient host is urban or in close proximity to humans, we should be particularly concerned.”
The study draws a future “network” of viruses jumping from species to species, and growing as the planet warms.
“Today we have easy and rapid means of investigation which allow us to react quickly in the event of the appearance of new viruses”, reassured Marc Eloit, of the Pasteur Institute. “We are also able to develop vaccines very quickly”, as we have seen with the Covid-19.
But “A whole line of new diseases are likely to emerge, potentially dangerous. We will have to be ready”, warned Eric Fèvre, professor specializing in veterinary infectious diseases at the University of Liverpool (United Kingdom) and at the International Livestock Research Institute (Kenya).
This means, according to him, “emphasizing the public health of populations” in the most remote and “better study the ecology of these natural areas to understand how the different species interact”.
Since the early 2000s, the “One Health” concept has been put forward: it promotes a multidisciplinary and global approach to health issues with close links between human health, that of animals and the environment. global ecological state.
France also launched in 2021 the international initiative “Prezode”, which aims to prevent the risks of zoonotic emergences and pandemics by strengthening cooperation with the most affected regions of the world.
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