“The interface between humans and animals has become quite unstable”alerted a few days ago Dr. Mike Ryan, Head of Emergencies at the World Health Organization (WHO).
“Disease incidence and amplification factors have increased”, according to him. We have just seen it with monkey cups, 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 vertebrates can transmit to humans. Some even end up being specifically humans, like Covid-19.
According to the World Organization for Animal Health, about 60% of new diseases are of zoonotic origin. Appeared thousands of years ago, since humans intensified their interaction with animals by taming them, they have seen their frequency increase sharply over the last twenty or thirty years.
This is about “the intensification of travel, which allows them to spread faster and in an uncontrolled way”stressed to AFP Marc Eloit, head of the Pathogen Discovery Laboratory at Institut Pasteur.
By occupying ever larger areas of the globe, humans are also helping to disrupt the ecosystem and encourage the transmission of viruses.
The intensification of factory use thus increases the risk of spreading pathogens between animals. Wildlife trade also increases human exposure to the microbes they can carry.
Deforestation increases the risk of contact between wild animals, domestic animals and human populations.
“When we clear forests, we reduce biodiversity; we lose animals that naturally regulate viruses, allowing them to spread more easily.”explained 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 habitable countries, a study published in Nature warned in late April.
But by mixing more, the species will transmit more of their viruses, which will promote the emergence of new diseases that can potentially be transmitted to humans.
“We need improved surveillance of both urban and wildlife so we can identify when a pathogen has jumped from one species to another.”said Gregory Albery, an environmental health specialist at Georgetown University in the United States and co-author of the study.
“And if the receiving host is in town or near people, we should be especially concerned.”
The study draws a future “network” of viruses that jump from species to species and grow in size as the planet warms. “Today we have easy and fast methods of investigation that allow us to react quickly in the event of new viruses”reassured Marc Eloit, of the Pasteur Institute.
“We are also able to develop vaccines very quickly”as we have seen with Covid-19.
“A whole host of new diseases are likely to emerge, potentially dangerous. We need to be prepared”warned Eric Fèvre, professor specializing in veterinary infectious diseases at the University of Liverpool (UK) and the International Livestock Research Institute (Kenya).
According to him, this means “emphasize the public health of the population” in the most remote environments 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, animal and environment, global ecological status.
France also launched in 2021 the international initiative “Prezode”, which aims to prevent risks of zoonotic occurrence and pandemics by strengthening cooperation with the most affected regions of the world.