Sunday, 24 February 2019

Zaire ebolavirus found in a bat in West Africa


The government of Liberia, in partnership with the Center for Infection and Immunity (CII) at the Columbia University Mailman School of Public Health and EcoHealth Alliance, announced the discovery of Ebola virus in a bat in Liberia. This is the first finding of Zaire ebolavirus in a bat in West Africa, adding to other evidence suggesting bats serve as a natural wildlife reservoir for Ebola and other related viruses. Scientists found both genetic material from the virus and ebolavirus antibodies in a Greater Long-fingered bat (Mineopterus inflatus) in Liberia's northeastern Nimba District. CII has been working to identify and characterize novel viruses at the intersection of humans and animals, on a global scale, for more than three decades. This work is a part of the USAID PREDICT project, which aims to better understand the animal reservoirs, seasonality, and transmission of viruses that can cause epidemic diseases.
Ebola virus belongs to the Filoviridae family which also includes the Marburg and Cueva viruses. Like other zoonotic diseases (SARS, influenza, and rabies), Ebola virus is harbored by a natural animal reservoir, in Ebola's case believed to include one or more species of bat, based on previous scientific studies. Prior Ebola outbreaks in Central Africa have been associated with deforestation and bushmeat hunting, where human cases were linked to contact with and consumption of chimpanzees, gorillas, and duikers that were infected. These animals were also victims of Ebola virus and it's still a mystery as to exactly how they were infected. However, there is substantial evidence that filoviruses, such as Ebola and Marburg virus, are carried by bats. Marburg virus was recently discovered for the first time in Sierra Leone in its known bat reservoir, but it has historically been difficult to identify bats infected with Ebola virus.


Bats play a critical role in ecosystems around the world, by removing pest insect species and pollinating fruiting trees, for example. The finding of Ebola virus in a bat should not be taken as a reason to exterminate, remove or harass bats in their natural environment. In fact, previous work shows that efforts to remove wildlife populations can lead to enhanced disease spread.

This is the first identification of Ebola virus in a bat in West Africa. There are six species of Ebola virus and Zaire ebolavirus is the one responsible for causing the West African Ebola epidemic which infected nearly 30,000 people between 2013 and 2016. Researchers at CII are working to determine whether the strain found in the bat is exactly the same one associated with the 2013-2016 outbreak. The evidence so far from about 20 percent of the virus' genome suggests that it is closely related. Zaire ebolavirus is also responsible for the ongoing outbreak in the Democratic Republic of Congo, which is now the second deadliest Ebola outbreak in history.

No human cases of Ebola are linked to this discovery and Liberia has remained free of any new human cases since the 2013-2016 outbreak. However, this finding brings us closer to understanding where human Ebola cases come from.

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology

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