He confirms that zoonoses have multiplied in recent years. Vertebrates transmit diseases that can even become specifically human, such as Covid-19. According to the World Organization for Animal Health, about 60% of new diseases are of zoonotic origin.
These are agriculture, travel and deforestation
Several elements lead to this phenomenon, in particular “the intensification of journeys that allow (diseases) to spread faster and in an uncontrolled way”, emphasized Marc Eloit, head of the Discovery of pathogens laboratory at the Institut Pasteur. By occupying ever larger areas of the globe, humans are helping to disrupt the ecosystem and encourage the transmission of viruses. The intensification of factory use also increases the risk of spreading pathogens between animals. The trade in wild animals 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 are losing animals that naturally regulate viruses, allowing them to spread more easily, ”explained Benjamin Roche, a biologist at the Research Institute for Development (IRD), a specialist in zoonoses.
The threat of global warming
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 their viruses more, which will promote the emergence of new diseases that can potentially be transmitted to humans.
The study draws a future “network” of viruses that jump from species to species and grow as the planet warms. “A whole host of new, potentially dangerous diseases are likely to emerge. We need to be prepared,” warned Eric Fèvre, a professor specializing in veterinary infectious diseases at the University of Liverpool and the International Livestock Research Institute.
The most important and recent diseases caused by zoonoses
The beginning of the 21st century was marked by several epidemics of new viruses associated with zoonoses. Caused by a new coronavirus, Sars-CoV-2 (the origin of which is still uncertain), Covid-19 appeared in China in late 2019, before spreading worldwide, killing more than 6.2 million people. died according to a report, at. end of May 2022, from the American University of Johns Hopkins.
Like and originating in China in 2002, the SARS virus (Severe Acute Respiratory Syndrome) was transmitted from bats to humans via civets, a wild mammal that at the time was sold in Chinese markets for his meat. Middle Eastern Respiratory Syndrome (MERS) is also within the corona realm and was first discovered in 2012 in Saudi Arabia, a viral respiratory disease caused by a new coronavirus transmitted by camels. It caused the deaths of a third of the infected cases with 850 victims in total.
Still associated with bats, and first identified in 1976 in the Democratic Republic of Congo, the Ebola virus has triggered a series of 21st century epidemics in Africa that have killed more than 15,000 people in total. . From the same family, the Marburg virus – a serious disease that causes severe hemorrhagic fever – originated in 1967 in Germany and Yugoslavia after working with green monkeys. It causes death for about 50% of those infected.