A rare strain of Ebola has prompted the World Health Organization to declare a public health emergency of international concern. Most of the cases have occurred in the Democratic Republic of Congo, with more than 100 suspected deaths and nearly 400 suspected infections as of Monday (May 18).
Here is what we know about this strain of the Ebola virus, known as Bundibugyo.
What is Bundibugyo Ebola?
The current Ebola outbreak – so far limited to the Democratic Republic of the Congo (DRC) and Uganda – is due to a rare strain of the virus known as Bundibugyo, named after Uganda’s Bundibugyo province where it was first identified during an outbreak in 2007-2008.
A second Bundibugyo outbreak occurred in 2012 in the DRC.
Bundibugyo kills 30 per cent to 40 per cent of infected people, making it less lethal than the more common Zaire strain, which causes death in up to 90 per cent, according to a global study published in 2024.
Bundibugyo is one of four species of the Ebola virus genus that cause life-threatening illness in humans.
All Ebola viruses are transmitted through direct contact with the bodily fluids of infected animals or humans or objects contaminated with such fluids.
Body fluid transmission is a particular risk for hospital workers. A US doctor working in the DRC has been infected in the current outbreak.
According to the World Health Organization, Ebola viruses initially cause flu-like symptoms including fever, fatigue, malaise, muscle pain, headache and sore throat that can start suddenly, followed by vomiting and diarrhea, and eventually internal and external bleeding and multi-organ failure.
Are there treatments for Bundibugyo?
There are no approved vaccines or drugs for the Bundibugyo Ebola virus. Emergency use authorisation would be necessary for deployment of any experimental treatments or existing treatments that have been effective against other strains.
Potential candidates that have helped to control Bundibugyo in trials in non-human primates include Merck’s Ervebo, Mapp Biopharmaceutical’s MBP 134, and Auro Vaccines’ VesiculoVax.
NanoViricides said its experimental antiviral drug NV-387, currently in clinical trials against mpox, could be effective against the Bundibugyo strain. It mimics the immune cell surface proteins to which all Ebola viruses attach themselves and could thereby act as a decoy to “soak up” the virus and prevent it from attaching to healthy cells.
Earlier in the pipeline, an mRNA vaccine being developed in China has shown promise against Bundibugyo in mice but has not yet been tested in primates.
For now, response efforts will rely on public health measures such as rapid case detection, isolation, contact tracing, infection prevention and control, safe burials, and community engagement, said Dr Daniela Manno of the London School of Hygiene & Tropical Medicine in a statement.
“These measures were critical in eventually controlling the 2014-2016 West Africa Ebola epidemic, the largest Ebola outbreak ever recorded, and if implemented rapidly and effectively, they can also help control this outbreak,” Manno said.