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For now, the monkeypox epidemic is under control, but the sequence of events is worrying many epidemiologists.

The new monkeypox epidemic that has broken out in Europe and the United States in recent weeks does not only pose a threat to public health. It is also an alarm signal.

More and more dangerous viruses, which have developed in animal populations, are penetrating the human population. bird flu. SEA. SARS-CoV-1. And of course SARS-CoV-2, which has killed 6.3 million people since the very first infection in Wuhan, China, 30 months ago.

It is not difficult to understand why these animal-to-human “zoonotic” viral epidemics are becoming more severe and frequent. We are cutting down more and more forests where animals live and exposing them to us and us to them. Climate change is only making the problem worse. The more deforestation increases, the greater the risk of viral epidemics. † The combination of climate change, population density and urban sprawl is worrying because I think we will continue to see new viruses that can cause disease in humans said Stephanie James, who heads a virus analysis lab at Regis University in Colorado.

The current monkeypox outbreak, which causes fever and painful skin rashes and kills about 1 in 100 cases, was first noticed in the UK in early May. It appears that a British resident contracted the disease while traveling in Nigeria, where the monkeypox virus is endemic in populations of rodents and monkeys. Despite the name, authorities have not identified exactly which animal transmitted the disease. The previous outbreak of monkeypox in the United States in 2003 was sparked by a shipment of pet prairie dogs from Ghana to Texas.

Transmitted through saliva or sexual contact, smallpox quickly spread to Europe, Australia, South America, and the United States. Health authorities have identified about 100 cases so far. No one has died yet during the current outbreak, but that could change as infections increase.

Compared to the new coronavirus, monkeypox is insignificant. For starters, smallpox isn’t nearly as contagious as Covid. † The virus does not stay in the air like SARS-CoV says James. And because monkeypox is related to smallpox, our vaccines against the latter can prevent the former. † There is still a reasonable chance of containing these outbreaks said Lawrence Gostin, an expert in global health at Georgetown University.

What worries many epidemiologists is what will happen next. While the double shock of Covid and smallpox was terrible, future epidemics could be even worse. And if the current trend continues, they are practically inevitable.

Clearing of land for crops, farms and cities is indeed increasing, particularly in Brazil, where President Jair Bolsonaro has undermined enforcement of environmental laws. For several years now, the world has been losing about 4 million hectares of forest per year, compared to 2.5 in 2011. Every year we cut down an area of ​​forest equal to the size of Cuba. All this deforestation not only puts workers in close contact with exotic species and their equally exotic diseases, but also causes animals to flee to suburbs and cities in search of shelter and food, increasing the risk of disease. The situation gets even worse when you factor in the illegal trade in wild animals for meat and pets.

We find that the increase in epidemics of zoonotic and vector-borne diseases between 1990 and 2016 is related to deforestationwrites a team of scientists led by Serge Morand of the University of Montpellier in a study published in 2021. The worst epidemics have occurred in Brazil, Peru, Bolivia, the Democratic Republic of the Congo, Cameroon, Indonesia, Myanmar and Malaysia, according to the study.

The worst-case scenario is that a virus worse than SARS-CoV-2 (either more contagious, more deadly, or both) jumps from animals to humans, causing an even more devastating pandemic than the current one. However, it is not a one-way street. Viruses can jump from animals to humans, then back to animals, and finally back to humans, mutating each time. This “reverse zoonotic transmission” can only produce more deadly viral variants, said Paul Anantharajah Tambyah, president of the Asia-Pacific Society for Clinical Microbiology and Infection, Singapore.

It’s high time to start sampling animal populations to try and identify the viruses that pose the greatest threat. † I think we really need to look at the idea of ​​”nightmare” viruses, ie zoonotic viruses that we haven’t encountered yet says James.

But preventing this pandemic requires more than just surveillance. As long as we continue to cut down the forests on our planet and expose ourselves to the animals that live in those forests, we will continue to catch viruses from those animals. It’s about when, not if, another such virus will go global.

David Axe

Translated by the editor

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