SARS, Mers, Ebola, avian flu, Zika, COVID-19, HIV, monkeypox… Encouraged by our lifestyles, zoonoses, diseases transmitted to humans by animals, have multiplied in recent years, raising fears of the emergence of new pandemics.
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“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.
We have just seen it with monkeypox, but not only, he warned.
This monkeypox –”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, approximately 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.
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 increasingly large areas of the globe, humans also contribute to disrupting the ecosystem and encouraging the transmission of viruses.
The intensification of factory farming thus increases the risk of the spread of pathogens between animals. Trade in wild animals also increases human exposure to the microbes they may carry. Deforestation increases the risk of contact between wildlife, domestic animals and human populations.
“When we deforest, we reduce biodiversity; we lose animals that naturally regulate viruses, which allows them to spread more easily, ”explained to AFP Benjamin Roche, biologist at the Research Institute for Development (IRD), specialist in zoonoses.
Climate change will also push many animals to flee their ecosystems for more livable lands, warned a study published in Nature at the end of April. However, by mixing more, the species will transmit their viruses more, 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 receiving host is urban or near humans, we should be particularly concerned.”
The study draws a future “network” of viruses jumping from species to species, and growing as the planet heats up.
“We now 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 Institut Pasteur. “We are also able to develop vaccines very quickly”, as we saw 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 environments and “better studying the ecology of these natural areas to understand how 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.
In 2021, France also launched the international “Prezode” initiative, which aims to prevent the risks of zoonotic emergences and pandemics by strengthening cooperation with the most affected regions of the world.