A pandemic can arise anywhere – De Groene Amsterdammer

Small horseshoe bat (Rhinolophus hipposideros), The Netherlands

Jeroen Steele / Canada / ANA

On the day when the researchers From Hong Kong First Evidence of SARS-CoV-2 Human-to-Human Transmission in Trade Journal scalpel – January 24, 2020 – Around the world, a team of scientists led by the United States is sending an ambitious scientific analysis to temper nature† Their message isn’t very cheerful: Climate change is causing all animal species to drift away, dramatically increasing the chance of viruses and other pathogens passing to other species and eventually to humans. This process is already underway and will only accelerate in the coming decades.

While their article is on the desk with someone temper natureThe coronavirus is being gripped by editors and swallowing up almost all the attention of scientists, the media, and the public. The pandemic that is only unfolding makes the article more relevant. It soon became the dominant hypothesis (though not definitively proven) that the coronavirus ‘jumped’ from bats to humans via another animal, possibly an anteater, in or near Wuhan.

According to American researchers, it is bats that can become the main supplier of new viruses to humans. In July 2020, Americans will already publish their article on the Internet, so that it has been widely cited by colleagues. Last month, the version reviewed by our fellow scientists appeared online at temper nature

That being the case, the team led by Georgetown University in Washington, D.C. calculated in their comprehensive model study: When the temperature increases due to climate change or becomes drier or wetter, and as a result, land use by humans changes, the animals seek refuge somewhere Else collectively – especially in the north or higher. Many animal species will be crippled by the fragmentation of their habitat (read: people are popping up everywhere), but bats are less bothered by this because they can fly. In addition, bats carry many viruses and make up at least twenty percent of all mammalian species. Only rodents harbor more viruses in total, but this is because they have twice the number of species.

The virus is not easily transmitted from every animal species to another, let alone humans. The more connected, the easier, in principle. But when climate change brings together animal species that previously lived in isolation, new chains of transmission can evolve that eventually reach humans – termed “zoonotic diseases.” This process is already underway, the authors write: the average temperature on Earth has already risen by more than one degree, and animal species have already drifted and come into contact with species they have not encountered before.

It is not individual to determine whether these climate change processes have contributed to the emergence of new viruses in humans since then. Research linking specific events to climate change is developing and has so far focused only on weather phenomena such as heat waves and floods. It is always a combination of factors.

“The relationship between climate change and the spread of wildlife and vectors, such as mosquitoes and their viruses is not new to our field, as the main role of bats has been mentioned before,” says Josan Verhagen, associate professor of virology at the Faculty of Veterinary Medicine of Utrecht University. In addition, the form is so general and thus coarse, that you miss or oversimplify all kinds of things. But we agree as experts that climate plays a role in this way in the spread of infectious diseases, and it is important to get this message across to a wider audience.

Although a lot because of the corona pandemic Surprisingly, the emergence of the Corona virus dangerous to humans was not surprising to experts. After all, the risk of epidemics is not only increasing because the world’s population is becoming increasingly mobile and interconnected. You can call this the “receiving side” of virus transmission, but there’s also a lot going on on the “sender side”.

We already know of some zoonotic diseases, such as the influenza viruses that cause seasonal influenza. But all kinds of pathogens are also advancing towards areas where they were not present or barely present before. For example, 2020 was not only the year when the Covid-19 virus took hold, many African countries were swept by the Ebola virus, and Nigeria recorded the highest number of infections so far from its cousin Lassa fever: more than a thousand cases of which 244 died Lassa fever is spread by rats.

The most obvious is the spread of mosquitoes, among other things, which live due to the high temperature in areas where they could not have lived before. For example, the tiger mosquito is advancing in Europe, where previously it was found only in Asia – thanks to the transport of goods, the mosquito has come to the continent, and the increase in temperature is pushing it north. It seems only a matter of time before he also settles in Holland. Tiger mosquitoes can transmit many diseases, including chikungunya and dengue fever.

Lyme disease spread by ticks has become more common in the Netherlands in recent years because ticks that spread this disease thrive best in higher temperatures. Another tick-borne disease, tick-borne encephalitis, is also expected to become more prevalent in the coming years. This is already the case in Switzerland, for example.

About ten thousand viruses can jump from animals (excluding birds) to humans

Viruses and other pathogens They pass from animals to humans for the first time. The possibility of that is huge. It is estimated that there are about ten thousand viruses currently circulating in mammals (excluding birds) that have the ability to jump to humans, about a quarter of the total number of viruses in these animal species. Some viruses also cause symptoms in those animals, but in some species that have infected a particular animal species for thousands of years, they usually cause mild or no symptoms. However, this does not mean that they are also harmless to other animal species, including humans. On the contrary: our immune system is less able to deal with viruses with which it is not familiar.

In recent decades, human behavior has greatly increased the chance of new zoonotic diseases. For example, due to the progress of cities and deforestation, an increase in intensive livestock farming or a combination of livestock and wild animals, trade in and consumption of wild animals and a change in eating behavior that brings people (on a larger scale) into contact with other animal species. So climate change comes on top of that.

Scientists can identify so-called “hot spots” where the risk of developing new infectious diseases is greatest in humans. In the temper natureAn article, American researchers have categorized parts of Southeast Asia and the African tropics in particular as hotspots for new contacts between animal species and thus virus exchange. In addition to these two regions, regions where virus exchange between animals coexists with a high human population density include southern China and India.

This does not mean that these are the only places where a new virus can appear. first author of temper natureAn article, ecologist Colin Carlson testified on the day the article appeared before Congress. He asserted that the deadliest epidemic in modern history, the Spanish flu of 1918, despite its name, very likely originated on a farm in Kansas. “An epidemic can start anywhere.”

Carlson cited as an example a measles-like virus found in Alaskan otters in 2004. Melting Arctic ice allowed animals to move more freely and spread the virus to otters, seals, and sea lions. Scientists and authorities closely monitored this in the following years. This virus does not pose any threat to humans, Carlson said, but similar processes can occur with other, more dangerous viruses.

Better animal control Viruses can reduce the chance of another outbreak, but the question is where to focus the most attention. Given the amount of viruses circulating in animals, it’s nearly impossible to monitor all of them. As Australian and New Zealand experts in Biology Plus He wrote, “Just as determining the exact animal origin of Sars-Cov-2 is like searching for a needle in a haystack, predicting which of myriad animal viruses will appear in humans is like searching for a very specific grain of sand on a seashore.” ‘

Moreover, Jossan Verhagen also emphasizes, that the relationship between transfer between animals and actual transmission to humans is not yet clear. straight forward† “There are still a few steps between that we as human beings can influence.”

For example, transmission is often carried out by livestock, where the chance of transmission can be reduced through targeted measures – or simply by reducing the number of livestock. And even if the switch does happen, a quick response — faster than during the coronavirus pandemic — could nip the outbreak in the bud and prevent disaster.

So Australian and New Zealand researchers argue in favor of intense monitoring especially when people and animals come together – that is, where the last step in the chain can occur.

That’s also what the team of virologist Marion Koopmans at Erasmus MC and the Center for Epidemic and Disaster Preparedness she co-founded focuses on: intensified surveillance of viruses, particularly in hot spots where the risk of new animal diseases is greatest. Philanthropist Bill Gates also stresses the importance of early detection. With his own Gates Foundation, he was investing in it pandemic preparedness In his recently published book, How do we prevent the next pandemic? He described the early detection of an outbreak as one of the most important tools in pandemic prevention. He suggests creating teams fully committed to this, in close contact with colleagues elsewhere in the world. It also emphasizes the importance of active surveillance, where doctors and scientists take more samples from patients, animals and in the environment, rather than passive surveillance that still prevails, where alarm bells only go off when Wuhan advances, as in the market. A “group” of patients with certain typical complaints.

What are the authors? temper natureThe same article attempts to stress that those who choose to focus more on adapting to climate change rather than combating it, will also have to opt for these impacts. Not least financially and economically, as the Corona pandemic has demonstrated. In doing so, they are also emphasizing something else the pandemic has demonstrated: especially that poor countries least able to adapt will foot the bill.

Carlson called on Congress at the end of April to commit to more ambitious animal control. Targeted monitoring, i.e. where advanced technology can help. “We’re on our way to real predictions in full swing,” Carlson said. We know which viruses are a threat and which animals we need to test for; Building early warning systems that predict the spread of disease as we know it from the weather. We can then use this information to develop universal vaccines, for example. This vision provides renewed hope that the Covid-19 pandemic will be the last.”

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