A New Discovery Could Help Prevent Future Ebola Transmission

As the Ebola outbreak in the Democratic Republic of the Congo enters its sixth consecutive month, a new discovery in Liberia is revealing more about how bats serve as a reservoir for Ebola and other filoviruses.

Investigators have announced that genetic material and antibodies from the Zaire ebolavirus strain were detected in a Greater Long-fingered bat in Liberia’s northeastern Nimba District. This discovery marks the first identification of Ebola virus in a bat in West Africa, the location of the 2013-2016 epidemic during which roughly 30,000 individuals were infected with the Zaire strain of Ebola.

The discovery was announced by the Liberian government who worked alongside investigators with the Center for Infection and Immunity at the Columbia University Mailman School of Public Health and EcoHealth Alliance.

“This discovery is a major step forward in understanding how Ebola outbreaks happen,” Jonathan Epstein, DVM, EcoHealth Alliance Vice President for Science and Outreach, said in a statement. “The West African Ebola epidemic was devastating, and it began with a single transmission from an animal to a person. It’s critical that we identify which animals naturally carry Ebola and related viruses—without knowing that, we can’t truly understand and reduce the risk of another outbreak occurring in the region.”

The investigators made the discovery using VirCapSeq-VERT, a tool invented by the Center for Infection and Immunity that improves the sensitivity of next-generation sequencing 1000-fold.

Greater Long-fingered bats are found in parts of West Africa and other regions. The bats tend to live in forests and caves, which limit human exposure to this particular species. The investigators are working to determine if Ebola is prevalent in these bats and also to determine the risk to humans.

At this time, the Liberian government is working to engage local communities to reduce the risk of exposure, to educate people about the positive impacts of bat species on pest control and the environment, and to prevent attempts to exterminate the species, which could increase the risk of exposure.

Investigators are working to determine whether the strain found in the bat is the same as the one associated with the 2013-2016 outbreak. So far, evidence from about 20% of the virus’ genome suggests that it is closely related to the outbreak strain.

"Now we have a target for more focused ecological and epidemiologic studies — in particular sampling this species through time to elucidate the natural transmission dynamics of the virus," Simon Anthony, DPhil, asistant professor of epidemiology, Center for Infection & Immunity at Columbia University Medical Center told Contagion® in an interview. "In addition, there are a couple of studies suggesting that virus ‘adapted’ to humans as the 2013-2016 epidemic progressed, but we don’t have the ‘original’ sequence of the virus (i.e. the bat version). Characterizing ebola virus in bats will also help us understand the process by which viruses adapt to humans."

It is important to point out that no human cases of Ebola are linked to this discovery and a human case of Ebola has not been detected in Liberia since the 2013-2016 outbreak. However, this finding brings us closer to understanding where human Ebola cases come from and presents the possibility that there are also other bat species that carry Ebola.

Zaire ebolavirus is also responsible for the ongoing outbreak in the North Kivu Province of the DRC, which is now the second deadliest Ebola outbreak in history with nearly 700 confirmed cases the outbreak. According to a situation report issued by the World Health Organization, the DRC outbreak “is in a critical phase as it is in its sixth month since the declaration of the outbreak. The outbreak continues to evolve in a particularly complex and challenging environment, marked by a volatile security context, which continues to hinder the implementation of key response activities.”

As of January 28, 2019, the Ministry of Health reports that there are 689 confirmed cases and 407 confirmed deaths. On Wednesday, January 23, 2019, 14 new cases were reported across the North Kivu province, marking the most cases declared in a single day since the outbreak was declared in August.

While Beni has been the epicenter of the outbreak for months, the latest hotspot is the city of Katwa located southwest of Beni.

Over the past 3 weeks, Katwa has recorded 68 of the 104 new cases detected in the outbreak, approximately 65% of the new cases.

The Ministry of Health attributes the rise in cases to disruptions in the response by rebel activities and protests, which have resulted in interruptions to immunization, household decontamination, and dignified and safe burials.

Additionally, community resistance continues to remain a barrier to prevention activities, with health officials reporting that despite the involvement of customary, religious, politico-administrative, and civil society authorities in the community, there are still individuals that resist vaccination and evaluation for symptoms.

While the reality of this ongoing outbreak is devastating and the words violence and resistance have appeared too many times in reports on outbreak response, perhaps the detection of the virus in a bat in Liberia provides hope that Ebola outbreaks can become a thing of the past.

For the most recent case counts in the North Kivu Province Ebola Outbreak, check out the Contagion® Outbreak Monitor.