In the eastern Democratic Republic of Congo (DRC), medical teams are working to contain an outbreak of Ebola caused by the Bundibugyo virus, a less common species of the virus family. As of early June, the outbreak has infected at least 695 people and resulted in 138 deaths. Care providers at newly established treatment centers are focused on supportive therapies such as rehydration, blood transfusions, and pain management, but there is currently no approved treatment specifically targeting Bundibugyo virus.
The Bundibugyo strain, first identified in 2007, differs significantly from the Ebola virus species that has driven most previous outbreaks. Treatments that are effective against Ebola virus do not necessarily work against Bundibugyo due to genetic differences. While two antiviral drugs—MBP-134 and remdesivir—have shown promise in laboratory and animal studies, comprehensive clinical trials for Bundibugyo-specific therapies have not yet been conducted, primarily because of the historically low incidence of this strain.
Medical researchers are now accelerating efforts to test potential treatments amid the current outbreak. The World Health Organization (WHO) has prioritized several candidates for clinical trials, including the monoclonal antibodies MBP-134 and maftivimab, as well as the antivirals remdesivir and obeldesivir. MBP-134 has demonstrated efficacy against Bundibugyo infection in nonhuman primates and has been administered in some human cases. Dr. Peter Stafford, an American physician infected with Bundibugyo virus in the DRC, received both MBP-134 and remdesivir during treatment in Berlin and was discharged on June 6, although it remains unclear whether these drugs contributed directly to his recovery.
Designing and launching clinical trials in an outbreak setting remains challenging. The current response is complicated by conflict in the region and limited healthcare infrastructure. However, researchers are employing innovative trial models that allow testing of treatments across outbreaks caused by different viruses. For example, remdesivir trials were initiated earlier this year during a Marburg virus outbreak in Rwanda, and data from these are expected to be combined with new trials against Bundibugyo virus.
In addition to treatments for infected patients, health officials are exploring strategies to prevent disease in people who have been exposed but are not yet symptomatic. A trial of obeldesivir, an oral antiviral related to remdesivir, is planned to assess its potential as post-exposure prophylaxis. Previous studies in monkeys have shown that obeldesivir can prevent the onset of illness when administered shortly after infection with Ebola virus or related filoviruses. If effective in humans, such prophylactic treatment could reduce transmission by enabling contacts to receive medication before symptoms develop.
Access to successful therapies remains a critical concern. While experimental drugs have been used to treat patients outside the outbreak zone, such as Dr. Stafford and his family, there is ongoing debate over the availability of these treatments to affected populations in the DRC and neighboring Uganda. Past Ebola outbreaks have seen promising antibody therapies developed with public funding and local origin fail to reach patients widely due to intellectual property rights and regulatory barriers. Some doses of monoclonal antibody treatments remain stockpiled in the United States rather than deployed in African countries where the disease is active.
Global health organizations and researchers emphasize the importance of ensuring that once treatments are proven effective, they are accessible to all affected communities. Meanwhile, efforts to conduct rigorous clinical trials continue under challenging conditions, with the goal of identifying lifesaving options for the population confronting this lethal virus.