Tout savoir sur les “zoonoses”, these epidemic diseases that will multiply in the future

What is the relationship between Covid-19, smallpox and Ebola? All are emerging virus epidemics related to “zoonoses.” More or less old, with or without a cure and more or less dangerous to humans, these diseases and infections have exploded in the 21st century. And everything suggests that things are not about to get better. 20 minutes tells you all about this great family of viruses.

What are zoonoses?

Zoonoses are all diseases transmitted to humans by animals. The list includes Sras, Mers, Ebola and bird flu, as well as zika, Covid-19, HIV and smallpox. For the “monkeypox” virus in English, they are infected animals, most often rodents, which transmit it. Regarding MERS, it comes from dromedaries in Saudi Arabia where it was first detected in 2012.

L’hôte naturel d’Ebola, first identified in 1976 in the Democratic Republic of the Congo, is the bat. Marburg’s disease, which causes severe bleeding fever, was identified in 1967 in Allemagne et Yugoslavie as a result of works on singes verts. Finally, Zika, chikungunya and dengue are all mosquito-borne and exploded in Latin America in 2015.

It is thus agitated, at the origin of infectious diseases, that vertebrate animals can transmit to humans, more finissent even through the specific human becoming, to the instar Covid-19 which is transmitted between humans. According to the World Organization for Animal Health, about 60% of emerging diseases are of zoonotic origin.

Why are there more and more?

If it is the animals that transmit zoonoses to humans, however, it is not their fault, but that of man and more precisely his way of life. Appearing thousands of years ago, since humans intensified their interactions with animals by domesticating them, they have seen their frequency greatly increase over the last twenty or thirty years. “The human-animal interface has become quite unstable,” said Dr. Mike Ryan, head of emergency at the World Health Organization (WHO). “Disease emergence and amplification factors have increased,” he said.

In this case, “the intensification of travel, which allows them to spread faster and in an uncontrolled manner,” said Marc Eloit, head of the pathogen discovery laboratory at the Institut Pasteur. But also the intensification of industrial livestock that increases the risk of spreading pathogens among animals. The wildlife trade also increases human exposure to the microbes they are likely to 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 makes them easier to spread, ”says Benjamin Roche, a biologist at the Institute for Developmental Research (IRD), a specialist in zoonoses.

Climate change is also pushing many animals to flee their ecosystems to more livable areas, a study in Nature warned in late April. However, by mixing, the species will transmit more of their viruses, which will promote the emergence of new diseases potentially transmissible to humans.

What are the risks to humanity?

“Today we have easy and quick means of investigation that will allow us to react quickly in the event of the appearance of new viruses,” said Marc Eloit of the Pasteur Institute. “We are also able to develop vaccines very quickly,” as we have seen with Covid-19.

Moreover, “a whole new line of potentially dangerous diseases is emerging.” He will have to be prepared, ”warns Eric Fèvre, a professor of veterinary infectious diseases at the University of Liverpool (UK) and the International Institute for Animal Research (Kenya). According to him, this means “focusing on the public health of the population” 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 concept of “one health” has been at the forefront: a multidisciplinary and global approach to health drinks has been promoted with a narrow lens between human health, animal health and the ecological state. global. France also launched in 2021 the international initiative “Prezode”, which aims to prevent the risks of zoonotic emergencies and pandemics and to ensure cooperation with the most relevant regions of the world.

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