WHO Declares Bundibugyo Virus Outbreak a Public Health Emergency, Adds First Diagnostic Test to EUL
Key Insights
WHO declared the Ebola disease (search) outbreak caused by Bundibugyo virus (search) in the DRC and Uganda a Public Health Emergency of International Concern (PHEIC) on May 17, 2026, with 1,406 confirmed cases and 438 deaths reported in the DRC alone.
The WHO added the first molecular diagnostic test for Bundibugyo virus (search) to its Emergency Use Listing, enabling rapid and accurate detection through genetic material identification in blood samples.
Unlike Ebola-Zaire strains, there are currently no approved Bundibugyo virus (search)-specific therapeutics or vaccines, making diagnostic tools and supportive care the primary response measures.
The World Health Organization (WHO) has declared the outbreak of Ebola disease (search) caused by Bundibugyo virus (search) (BDBV) in the Democratic Republic of the Congo (DRC) and Uganda a Public Health Emergency of International Concern (PHEIC), while simultaneously adding the first molecular diagnostic test for the virus to its Emergency Use Listing (EUL). The twin announcements mark a critical escalation in the global response to what has become the largest recorded outbreak of Ebola disease caused by BDBV.
As of the latest reporting, 1,406 laboratory-confirmed cases and 438 deaths have been documented in the DRC alone, with the outbreak continuing to expand across multiple health zones in Ituri Province and beyond.
A Rapidly Evolving Outbreak
The PHEIC determination, made by WHO Director-General Dr. Tedros Adhanom Ghebreyesus on May 17, 2026, followed consultation with the affected States Parties and was based on several alarming epidemiological indicators. As of May 16, 2026, eight laboratory-confirmed cases, 246 suspected cases, and 80 suspected deaths had been reported in Ituri Province across at least three health zones: Bunia, Rwampara, and Mongbwalu.
International spread has already been documented. Two laboratory-confirmed cases, including one death, were reported in Kampala, Uganda, on May 15 and 16, 2026, among individuals traveling from the DRC. Both confirmed cases were admitted to intensive care units in Kampala.
"The high positivity rate of the initial samples collected (with eight positives among 13 samples collected in various areas), the confirmation of cases in Kampala, the increasing trends in syndromic reporting of suspected cases and clusters of deaths across the province of Ituri all point towards a potentially much larger outbreak than what is currently being detected and reported," the WHO stated in its declaration.
At least four deaths among healthcare workers in a clinical context suggestive of viral hemorrhagic fever have been reported, raising concerns about healthcare-associated transmission and gaps in infection prevention and control measures.
No Approved Vaccines or Therapeutics
A critical factor distinguishing this outbreak from previous Ebola events is the absence of approved Bundibugyo virus (search)-specific countermeasures. Unlike Ebola-Zaire strains, for which vaccines and therapeutics have been developed and deployed, there are currently no approved Bundibugyo virus-specific therapeutics or vaccines. The WHO has called on affected States Parties to implement clinical trials to advance the development and use of candidate therapeutics and vaccines, supported by partners.
First Diagnostic Test Listed Under EUL
Less than two weeks after the PHEIC declaration, the WHO added the first molecular diagnostic test for Bundibugyo virus (search) to its Emergency Use Listing. The test detects the virus by identifying its genetic material in blood samples, enabling rapid and accurate confirmation of infection.
"Public health emergencies require not only speed, but also confidence that the health products being used meet standards for quality, safety and performance," said Dr. Yukiko Nakatani, WHO Assistant Director-General for Health Systems, Access and Data. "During a fast-moving outbreak, timely access to quality-assured diagnostic tests can make a critical difference in containing transmission. Through this Emergency Use Listing, WHO is helping countries access trusted diagnostic tools more rapidly so that they can respond more effectively."
The WHO's EUL procedure assesses the quality, safety, and performance of essential health products based on available evidence, ensuring they meet minimum international standards and address the needs of low- and middle-income countries. The listing supports United Nations procurement agencies and governments in making informed decisions about product procurement and use in public health emergency settings.
Laboratory Capacity Expansion
With support from WHO and the Africa Centres for Disease Control and Prevention (search) (Africa CDC), laboratory testing capacity has expanded significantly. The network has grown from a limited number of sites—primarily the Institut National de Recherche Biomédicale (search) in Kinshasa and Goma, with an estimated combined capacity of approximately 200–400 tests per day—to a broader network of 10 laboratories across affected provinces, with a reported capacity of over 2,000 tests per day.
In parallel, WHO and Africa CDC, with partners including PATH, FIND, and CHAI (search), and with support from Unitaid (search), are establishing a joint validation platform to rapidly evaluate the performance of a selection of diagnostic products, including laboratory-based molecular tests, near-point-of-care molecular tests, and antigen rapid diagnostic tests. The platform will generate critically needed clinical evidence on the performance of these products in outbreak settings.
International Coordination and Response
The WHO has issued comprehensive advice for affected States Parties, neighboring countries, and all other States Parties. Key recommendations include activation of national emergency management mechanisms, enhanced surveillance and contact tracing, strengthened infection prevention and control in health facilities, and establishment of specialized treatment centers with optimized intensive supportive care.
The Director-General emphasized that no country should close its borders or place restrictions on travel and trade, stating that such measures "are usually implemented out of fear and have no basis in science" and can push movement to unmonitored informal border crossings, increasing disease spread risk.
Additional applications for BDBV in vitro diagnostics submitted through the EUL procedure are currently under review, as the WHO continues to work with manufacturers, global partners, and countries to expand access to quality-assured health products for this ongoing emergency.