Published
CoronavirusTo avoid the next pandemic, let’s plant trees!
A scientist has found a way to predict the spread of viruses by bats and how to prevent them: by providing a winter habitat for these animals.
When flying foxes are close to trees that flower in winter, they go less towards humans and spread their virus little.
Getty Images/iStockphoto
Peggy Eby looked at the spread of pandemics by flying foxes, a type of bat that lives in Australia. This wildlife ecologist at the University of New South Wales in Sydney has been studying them for 25 years.
These bats harbor a virus called Hendra, which causes a very rare but deadly respiratory infection that kills one in two infected people. The Hendra virus, like Nipah, SARS-CoV and SARS-CoV-2 (the virus that caused the Covid19 pandemic) is a bat virus that has spread to humans. These viruses often reach humans via an animal (the pangolin has been suspected for SARS-CoV-2), sometimes with fatal consequences. Understanding whether certain conditions favor these epidemics might therefore be useful in preventing future ones.
Epidemics following droughts
And that’s what Peggy Eby and her team did, who even discovered a way to predict the spread of viruses up to two years in advance. In fact, outbreaks have been documented when bats experience dietary stress. This comes following a year when El Niño, the climatic phenomenon, is strong and causes droughts in Australia, can we read in “Nature“. Flying foxes lived as nomads, moving en masse from one forest to another in search of food. Today, bats have changed their way of life and split into a multitude of small groups, living near urban and agricultural areas.
This brings them closer to humans… and horses. Because it is via their urine, their excrement and the remains of chewed pulp that the flying foxes spread their virus on the grass which the horses then eat, which risk being infected and infecting humans. These contamination peaks were spotted following dry years, bats saving their meager strength by moving less and favoring agricultural areas.
A bizarre exception in 2020
The researchers tested their model, which was confirmed each time… except for 2020. However, there was a strong El Niño in 2018, followed by a drought in 2019, but no major Hendra epidemic. In trying to figure out what happened, scientists discovered that in the winter of 2020, a forest of red gum trees bloomed near the town of Gympie, attracting some 240,000 bats. And such winter blooms occurred in various regions in 2021 and 2022.
By identifying the increased risk of contamination by bats, the researchers therefore also found the solution: plant trees near places where many flying foxes live. Thus, by restoring the habitats of these few species that flower in winter, there would be less fallout in horses, and potentially in humans. This method might be applied to other bats and virus-spreading species. By restoring their habitats “maybe we can prevent the next pandemic,” says Raina Plowright, disease ecologist and co-author of the‘study at Cornell University in Ithaca, New York.
