Bundibugyo Virus: Why This Ebola Disease Outbreak is Different

An MSF expert on epidemic response answers common questions about the outbreak of Ebola disease currently sweeping through parts of DR Congo.

May 21, 2026

MSF teams train staff at Kyeshero Hospital in Goma, North Kivu province, on how to work in an Ebola environment.MSF teams train staff at Kyeshero Hospital in Goma, North Kivu province, on how to work in an Ebola environment. | DR Congo 2026 © Maria Elena del Carre/MSF

Outbreaks and epidemics

On May 15, 2026, an Ebola disease outbreak was officially declared in northeastern Democratic Republic of Congo (DRC), where Doctors Without Borders/Médecins Sans Frontières (MSF) teams have several programs providing health care to local communities impacted by conflict, epidemics, and lack of access to health care. Authorities have now reported more than 500 suspected cases and 130 deaths across multiple health zones, and several cases have been confirmed across the border in Uganda.  

John Johnson is MSF’s medical lead for epidemic response. Here, he explains what is different about this outbreak and some of the challenges our teams anticipate facing.

What makes this outbreak different from previous outbreaks of Ebola disease?

What makes this outbreak different and significantly harder to fight is the type of virus that causes Ebola disease. This is the Bundibugyo virus — not the same virus the world knows from the major West Africa epidemic that occurred between 2014 and 2016. That outbreak, and the 2018–2020 one in DRC, ultimately drove major scientific advances: Vaccines and treatments now exist for that specific virus, known as “Ebola virus” (formally called the “Zaire virus”). But for the Bundibugyo virus — which also causes Ebola disease — no vaccine or treatment has been approved so far.

This is the 17th Ebola disease outbreak DRC has experienced since the first case was discovered in 1976, and the third to specifically involve the Bundibugyo virus, following outbreaks in Uganda in 2007–2008 and in DRC in 2012.  

The MSF team sets up an Ebola isolation zone at Kyeshero Hospital in Goma, North Kivu province.

Are there vaccines available to fight this outbreak?

There are currently two approved vaccines against Ebola disease, but neither is approved for use in cases of infection with the Bundibugyo virus.

The Ervebo vaccine (rVSV-ZEBOV) can be used to limit the spread of the disease through a so-called “ring vaccination” strategy, meaning it is administered to people who have been in contact with an infected individual, secondary contacts, and health care workers. There is another vaccine that can be used during outbreaks for people at risk of exposure to the virus, and as a preventive measure before outbreaks for frontline responders or those living in areas not yet affected by the outbreak.  

Understanding the Ebola outbreak

Why this Ebola outbreak is especially urgent and challenging to control

However, these two vaccines are currently only approved against the most common virus responsible for Ebola disease — the Ebola (formerly known as Zaire) virus — not Bundibugyo.

Discussions are underway within the World Health Organization to determine which vaccine candidates can be tested in emergency clinical trials for the Bundibugyo virus, as was done in previous Ebola disease outbreaks. MSF is ready to contribute to this research, as we did in DRC in 2019. Those trials led to the approval and market release of the two vaccines [mentioned above] and treatments. 

Students wash their hands before going to class at Mwanga College in Goma. Handwashing is a part of Ebola virus prevention measures.

Is there a treatment for the Bundibugyo virus?

There is currently no approved treatment for Ebola disease caused by Bundibugyo virus. The two monoclonal antibodies that were licensed following clinical studies conducted in DRC between 2018 and 2020 [showed monoclonal antibody treatments improved the chances of survival for people with the Ebola (also known as Zaire) virus, but not the Bundibugyo virus. 

That said, antiviral candidates and experimental monoclonal antibodies do exist [for Bundibugyo virus], though their efficacy has yet to be established.In the absence of a specific treatment, care relies primarily on symptom management (such as fever, headache, vomiting, and diarrhea) and intensive supportive therapy aimed at improving patients' chances of survival. This includes fluid replacement, oxygen support, and close blood and cardiac monitoring. During the two previous Ebola disease outbreaks caused by Bundibugyo virus, the estimated fatality rate was between 25 and 40 percent. [While still devastating, this is far lower than the fatality rate of the Ebola (formerly Zaire) virus without treatment.]

Teams load an MSF truck with emergency response supplies at the airport in Bunia, Ituri province. This shipment includes 3,000 items of personal protective equipment (PPE) and medical supplies for the Ebola disease response.

What detection tools are available?

An additional major obstacle in the response to this outbreak is the ability to rapidly diagnose those affected by the disease. PCR tests require virus-specific diagnostic kits. However, these are currently available in insufficient quantities for the Bundibugyo virus, which considerably slows down case confirmation and, as a result, the implementation of contact tracing and patient isolation.

What else can be done to limit the spread of the Bundibugyo virus?

In the absence of approved treatments and vaccines, the response rests on a combination of epidemiological and public health measures, including:  

Early isolation of suspected and confirmed cases  

Daily monitoring of contacts for 21 days with immediate quarantine at the onset of symptoms

Strict infection prevention and control protocols (e.g., hand hygiene, waste management, chlorinated water points, and PPE [personal protective equipment] for health care workers)

Safe and dignified burials to prevent transmission during funeral rituals

On-the-ground epidemiological work to understand how the virus is spreading  

It is also critical to ensure continued access to regular health care for people in affected areas.

But none of this is effective without sustained community engagement — informing people about what is happening and building trust. This is a far more difficult task in contexts like DRC, marked by insecurity and limited access to health care.