WHO Adds First Molecular Diagnostic Test for Bundibugyo Virus to Emergency Use Listing Amid Expanding Outbreak

Today, the World Health Organization (WHO) announced a pivotal step in global health security, formally adding the first molecular diagnostic test for Bundibugyo virus (BDBV) to its Emergency Use Listing (EUL). This crucial development comes as the world grapples with the largest recorded outbreak of Ebola disease caused by BDBV, a highly virulent pathogen responsible for severe, often fatal, hemorrhagic fever. The newly listed test is designed to rapidly and accurately detect the virus by identifying its genetic material in blood samples, offering a vital tool for confirming infections and strengthening the global response to this escalating public health crisis.

The inclusion of this diagnostic tool in the WHO’s EUL procedure underscores the organization’s commitment to accelerating access to essential health products during public health emergencies. The EUL mechanism rigorously assesses the quality, safety, and performance of health products based on the best available evidence, ensuring they meet stringent international standards while also addressing the specific needs and logistical challenges often encountered in low- and middle-income countries (LMICs). By fast-tracking the availability of reliable diagnostics, the WHO aims to facilitate early case detection, enable timely clinical care, bolster disease surveillance efforts, and enhance the overall effectiveness of outbreak response strategies. Furthermore, the EUL designation serves as a critical guide for United Nations procurement agencies and national governments, empowering them to make informed decisions regarding the acquisition and deployment of these vital products in emergency settings.

Understanding the Bundibugyo Virus and its Current Threat

Bundibugyo virus is one of six recognized species within the Ebolavirus genus, notorious for causing severe viral hemorrhagic fever in humans. While less commonly discussed than its infamous cousin, Zaire ebolavirus (responsible for the devastating West African epidemic of 2014-2016), BDBV is equally capable of causing widespread suffering and high mortality rates. Historically, BDBV was first identified in 2007 during an outbreak in Bundibugyo District, Uganda, which affected 149 people and resulted in 37 deaths, marking a case fatality rate of approximately 25%. Symptoms of Bundibugyo virus disease are similar to other forms of Ebola, typically manifesting 2 to 21 days after exposure. These can include sudden onset of fever, intense weakness, muscle pain, headache, and sore throat, followed by vomiting, diarrhea, rash, impaired kidney and liver function, and, in some cases, both internal and external bleeding. The virus primarily spreads from wild animals to humans and then through human-to-human transmission via direct contact with the blood, secretions, organs, or other bodily fluids of infected people, or with surfaces and materials (e.g., bedding, clothing) contaminated with these fluids.

The current outbreak, declared a Public Health Emergency of International Concern (PHEIC) by WHO Director-General Dr. Tedros Adhanom Ghebreyesus on May 17, 2026, has escalated dramatically, primarily affecting the Democratic Republic of the Congo (DRC) with spillover cases also reported in neighboring Uganda. This declaration highlighted the severe risk posed by the outbreak, which at that time had already shown significant expansion and challenged existing response capacities. As of today, the situation remains critical, with 1,406 laboratory-confirmed cases and 438 deaths reported in the Democratic Republic of the Congo alone. This grim tally underscores the urgent need for enhanced diagnostic capabilities to interrupt transmission chains and provide life-saving care. The fatality rate in the current outbreak, while varying, often hovers around 30-40%, representing a significant public health burden and a severe threat to community stability in affected regions.

The Significance of the Emergency Use Listing

Dr. Yukiko Nakatani, WHO Assistant Director-General for Health Systems, Access and Data, emphasized the critical importance of the EUL in emergency contexts. "Public health emergencies require not only speed, but also confidence that the health products being used meet standards for quality, safety and performance," Dr. Nakatani stated. "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." Her comments highlight the dual imperative of rapid deployment and unwavering quality assurance that underpins the EUL process.

The EUL pathway is distinct from standard prequalification, designed specifically for health products needed urgently in emergency scenarios for which no WHO-prequalified alternative exists, or for products that address an urgent public health need and are undergoing a full prequalification assessment. The process involves a rigorous review of available data on quality, safety, and performance, often relying on a combination of laboratory validation, clinical studies, and manufacturer data. For BDBV, where rapid detection is paramount, a molecular diagnostic test offers significant advantages over less sensitive or specific methods. By identifying the virus’s genetic material, these tests can confirm infection even in early stages, sometimes before symptoms are fully manifest, allowing for quicker isolation of cases, tracing of contacts, and initiation of appropriate medical care. This speed is indispensable in breaking the chain of transmission, particularly in densely populated or highly mobile communities.

A Chronology of Response and Scientific Acceleration

The timeline of the response to the BDBV outbreak demonstrates a rapid, coordinated international effort. Less than two weeks after the PHEIC declaration on May 17, 2026, the WHO issued an urgent call for manufacturers of in-vitro diagnostics (IVDs) for Bundibugyo virus to submit Expressions of Interest for Emergency Use Listing. This proactive measure signaled the global health community’s recognition of the immediate need for reliable diagnostic tools. Manufacturers were invited to present their products for expedited review, demonstrating the WHO’s agility in mobilizing resources and expertise to address emerging threats. The swift processing of the first successful application, culminating in today’s EUL announcement, reflects the efficiency and dedication applied to public health crises of this magnitude. This rapid turnaround from PHEIC declaration to EUL listing is a testament to the accelerated procedures put in place for emergencies, bypassing the longer timelines typically associated with full prequalification processes, without compromising on critical safety and efficacy standards.

The EUL is not an endpoint but a catalyst. It clears the path for procurement and deployment, but the ultimate success depends on the capacity to utilize these tools on the ground. In anticipation of increased demand and with robust support from the WHO and the Africa Centres for Disease Control and Prevention (Africa CDC), laboratory testing capacity in the affected regions has already seen substantial expansion. Initially, testing was heavily centralized, primarily at a limited number of sites such as the Institut National de Recherche Biomédicale (INRB) in Kinshasa and Goma, DRC. These facilities had an estimated combined capacity of approximately 200–400 tests per day. Through strategic investment and logistical support, this network has broadened significantly to include 10 laboratories across the affected provinces, collectively boasting a reported capacity of over 2,000 tests per day. This tenfold increase in daily testing capability is transformative, enabling more comprehensive surveillance and quicker responses across a wider geographical area.

Broader Impact and Collaborative Future

The enhanced diagnostic capacity, coupled with the EUL for a quality-assured molecular test, has profound implications for managing the current outbreak and preparing for future ones. Rapid and reliable diagnosis is not merely about identifying a case; it is the cornerstone of effective public health intervention. It allows for prompt isolation of infected individuals, thereby preventing further spread. It guides timely and appropriate patient care, which can significantly improve outcomes and reduce mortality. Furthermore, it provides crucial data for epidemiological surveillance, allowing health authorities to track the outbreak’s trajectory, identify hot spots, and allocate resources more efficiently. Without accurate and swift diagnostics, outbreaks can spread unchecked, overwhelming health systems and prolonging suffering.

The WHO’s efforts extend beyond individual product listings. The organization continues to engage closely with manufacturers, global partners, and national governments to ensure the widespread availability and equitable access to safe, effective, and quality-assured life-saving health products. Several additional applications for BDBV IVDs submitted through the EUL procedure are currently under review, indicating a robust pipeline of potential diagnostic tools that could further strengthen the global response.

In a parallel and equally vital initiative, the WHO and Africa CDC, in collaboration with key partners including PATH, FIND, and CHAI, and with financial backing from Unitaid, are establishing a joint validation platform. This innovative platform is designed to rapidly evaluate the performance of a diverse range of diagnostic products. This includes not only laboratory-based molecular tests but also near-point-of-care molecular tests and antigen rapid diagnostic tests. The goal is to generate critically needed clinical evidence on how these products perform in real-world outbreak settings, where environmental conditions, logistical challenges, and patient demographics can significantly influence diagnostic accuracy and utility. This collaborative approach ensures that the tools deployed are not only technically sound but also practically effective and adaptable to the dynamic nature of emergency response.

The listing of the first molecular diagnostic test for Bundibugyo virus represents a significant milestone in the ongoing battle against this deadly pathogen. It is a testament to the power of scientific innovation, international collaboration, and rapid regulatory action in safeguarding global health. As the BDBV outbreak continues to challenge health systems in the DRC and Uganda, the availability of this quality-assured diagnostic test offers a renewed sense of hope and a tangible means to bring the expanding crisis under control, ultimately working towards a healthier and more secure future for all.