The largest recorded outbreak of Ebola disease due to Bundibugyo virus (BVD) continues to expand in the Democratic Republic of the Congo (DRC), prompting international efforts to improve diagnosis and treatment. As case counts continue to rise, the World Health Organization (WHO) has introduced a newly validated diagnostic test and launched an international clinical trial to evaluate potential treatments.

As of July 15, health authorities reported 2011 confirmed cases and 754 deaths in the DRC. In Uganda, the outbreak has remained unchanged since June 21, with 20 confirmed cases and two deaths.

Speaking with Science Media Center Germany (SMC), Maximilian Gertler, MD, specialist in internal medicine and tropical medicine and head of the Working Group on Infection Prevention and Control in Health Care Settings/Epidemic Preparedness, Charité - Universitätsmedizin Berlin, said, “This Ebola outbreak caused by the Bundibugyo virus is already larger than the two previously known outbreaks in 2007 (Uganda) and 2021 (DRC). Significantly more provinces are affected — although about 71% of the cases are concentrated in the health zones of Bunia Rwampara, Mongbwalu, and Nizi, all in Ituri Province — and we are seeing 10 times as many cases as in the two previous outbreaks combined.”

Patient Transfer

The outbreak continues to pose a substantial risk for healthcare and humanitarian workers. Physicians at University Hospital Frankfurt are treating a US citizen who contracted BV while on a humanitarian mission in the DRC. His condition has been reported as stable.

Since there is currently no approved vaccine or established specific treatment for BVD, management focuses on intensive supportive care, including fluid and electrolyte replacement, symptom management, and close monitoring for organ dysfunction. The treating physicians have not disclosed whether experimental antiviral agents or monoclonal antibodies are also being administered.

In May, another US physician who contracted BVD while on a medical mission in the DRC was treated at Charité - Universitätsmedizin Berlin, Berlin, Germany. After being transferred to Germany, he received the experimental monoclonal antibody MBP134 and was discharged approximately 2 weeks later after making a full recovery.

Limited Options

The current outbreak is caused by BV, one of the three Ebola virus species known to cause major outbreaks in humans. The virus is transmitted initially from animals to humans and subsequently spreads through direct contact with infected individuals, the bodies of people who have died from the disease, bodily fluids, or contaminated surfaces.

“There is no conclusive evidence that the virus has undergone any significant genetic or biological changes that would make it more virulent or contagious — or, conversely, less so. The case fatality rate currently being observed is about 33%. This is lower than the rates seen in previous Bundibugyo outbreaks. However, not much can be concluded from this at this point,” Gertler said.

The outbreak initially went undetected because commercially available diagnostic tests were designed to detect Zaire Ebola virus and could not identify BV.

Rapid Diagnostics

That may soon change. On July 2, the WHO added a molecular diagnostic test for BV to its Emergency Use Listing (EUL), giving affected countries access for the first time to a validated assay that can reliably detect the virus in blood samples.

WHO’s EUL procedure assesses the quality, safety, and performance of essential health products based on the available evidence to ensure they meet minimum international standards, particularly for use in resource-limited settings such as low- and middle-income countries.

Through this mechanism, WHO aims to accelerate the evaluation and authorization of medical products, including diagnostic tests, vaccines, and therapeutics, during public health emergencies.

Meanwhile, the WHO, the Africa Centres for CDC, and other international partners are developing a joint platform to evaluate additional diagnostic tools. The initiative will assess both molecular laboratory tests and point-of-care diagnostic systems, including rapid antigen tests.

Treatment Trial

Efforts to improve treatment are also underway. On July 2, in a major international effort to evaluate potential treatments for BVD, the PARTNERS clinical trial was launched in the DRC. The study is evaluating two antiviral treatment strategies. One is the monoclonal antibody MBP134, which has shown promising activity against multiple Ebola virus species in previous outbreaks. The other is remdesivir, an antiviral agent originally developed for other viral infections. Researchers are also assessing whether combination therapy improves treatment outcomes.

The treatments were selected following scientific review by the WHO Technical Advisory Group, which considered laboratory findings, safety data, and experience from previous Ebola outbreaks.

In addition to the assigned study treatment, all participants received comprehensive supportive care consistent with current WHO recommendations, including fluid and electrolyte replacement, oxygen therapy, blood pressure support, and pain management. Participants are monitored closely for at least 28 days after enrollment.

A distinctive feature of the PARTNERS trial is that it is being conducted during the ongoing outbreak, allowing emerging evidence to inform patient care in real time instead of years after the epidemic has ended.

Future Outlook

Definitive treatment data are unlikely to be available soon. For now, Gertler considers the situation critical. “Nearly 60 days after the outbreak was confirmed, we continue to see a rising number of new cases each week. Overall, the number of cases continues to rise faster than we have seen in previous Ebola outbreaks. We are still observing an expansion of the outbreak. Most of the new cases involve people who were not previously identified as contacts of known cases. We therefore still have an incomplete picture of the actual epidemiological situation,” Gertler said.

Martin Grobusch, PhD, director of the Center for Tropical and Travel Medicine, Department of Infectious Diseases, Amsterdam University Medical Center (Academic Medical Center), Netherlands, offered a more optimistic assessment.

Speaking with SMC, he said, “Although the number of patients and deaths is still rising, it is now estimated that 85%-95% of all contacts can be traced. Ultimately, it is not the availability of a vaccine but rather contact tracing and the identification and treatment of patients (fluid replacement, administration of antimalarial drugs and antibiotics) that will bring the outbreak under control. However, given its scale, the outbreak will likely continue into next year.”

This story was translated from Medscape’s German edition.