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The Ebola outbreak that began in 2013 in West Africa, infecting nearly 30,000 people and killing 11,000 people by its end in 2016, has long left scientists puzzled over a question key: where does the virus come from?
Now, a consortium of scientists has discovered Zaire's Ebola strain – one of six known virus types – in a bat species living in a cave, shedding light on the possible origins of the epidemic.
This discovery is the result of research conducted by Jonathan Epstein, V02, MG02, and Jim Desmond, V08, VG08, of the EcoHealth Alliance, as part of the USAID-funded PREDICT project. During the Ebola outbreak in 2013-2016, people infected with the Ebola virus in Zaire in Liberia and neighboring countries, Sierra Leone and Guinea, and the surprise epidemic made a splash. snow and have become the deadliest in history.
Tufts now he's been talking to Desmond, who trained and supervised the field bat testing team in Liberia, on how they finally found Zaire's ebolavirus in an animal and why such research is needed to prevent future pandemics.
Tufts now: Why did you look for Ebola and other viruses in wildlife?
Jim Desmond: We are trying to prevent the next global pandemic. The world has seen an increase in emerging infectious diseases in recent decades. Seventy percent of these diseases are zoonotic – which means they come from animals – and about 75% of these zoonotic diseases come from wildlife.
Doctors will always tell you that it is better to prevent the disease than treat it once it becomes serious. The work we do in PREDICT is disease prevention globally – a pandemic protection similar to the way physicians approach disease prevention at the individual level.
Human development is increasingly encroaching on wilderness areas, so humans are now coming into contact with animals with which they may have never been in contact before. If we want to prevent epidemics of Ebola, Marburg, SARS and other wildlife-transmitted diseases, it is important to understand where and how these viruses circulate in nature, as well as the factors that contribute to these outbreaks. For example, if we had made this finding before the Ebola outbreak 2013-2016 in West Africa, the public health authorities would have had the resources to better respond to its early days.
What did it take to find this strain of Ebola in a bat?
When we started this research, our goal was to sample many bats belonging to a wide range of species. It is very difficult to find a virus that circulates in a population of bats – it's like finding a needle in a haystack.
We believe that they transmit the Ebola virus between them, but that the virus can be seasonal and that infected animals do not excrete it long. We think that sounds like this brief period of colds, coughs and sneezes. This period pbades quickly and you always have a cold, but do not infect others.
When we capture, test and drop bats, we know that the chances of finding Ebola are minimal. So we have to sample many animals in the hope of catching the right bat at the right time. As we travel to each location for a few days for sampling, we must be lucky to catch a bat just as it transports and eliminates the virus.
What did you find?
We found about 20% of the genome of Ebola Zaire in an oral swab of a small species of insect-eating bats, called Miniopterus inflatus, or the largest bat The same bat also had neutralizing antibodies indicating exposure to Ebola Zaire, which further reinforced the results.
Of course, this discovery, while exciting, is not definitive. We need to do more research to learn more about this species of bat, as well as about other species of bats that could co-populate with them. The PREDICT project is coming to an end this year, but we will be seeking additional funding to continue our work in the field.
How does this new information help protect human health?
Some types of bats live in the attic of houses and thatched roofs, but this species of bat lives mainly in caves and abandoned mine shafts. The good news is that these bats do not usually come into contact with humans unless people go there.
The takeaway message is quite simple: avoid these areas and do not touch the bats. In West and Central Africa, where people eat bushmeat, public health officials must also make it known that no one should hunt or eat bat, which seems to be one of the biggest interfaces. risk for an Ebola virus spread event.
What should the public know about bats?
When such news appears, people's first reaction is often to want to exterminate bats. It's exactly the wrong thing to do, for several reasons. First of all, if you go to a cave trying to kill a lot of bats, you increase your risk of exposure. Many bats will also disperse to new locations, increasing the risk of spreading diseases. And finally, once humans leave this habitat, bats will come back and repopulate the cave. Some studies have shown that when we try to eliminate what humans regard as a harmful animal species, the situation often only worsens.
Bats are extremely important for the environment and the ecosystems we all share. Insect-eating bats, like the species we have found, infect tons of insects, thus reducing the risk of other serious human diseases such as malaria, dengue fever and the Zika virus. Meanwhile, fruit bats are really essential for seed dispersal and pollination in agriculture and in the wild.
Genevieve Rajewski can be reached at [email protected].
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