Update on Ebola Bundibugyo Outbreak

Executive summary

The Ebola outbreak caused by Bundibugyo virus disease (BVD) is affecting the Democratic Republic of the Congo and Uganda, with confirmed DRC cases in Ituri, Nord-Kivu, and Sud-Kivu provinces and Uganda cases linked to the DRC outbreak. As of 11 June update, DRC had reported 676 confirmed cases and 136 confirmed deaths as of 10 June, while Uganda had reported 19 confirmed cases, two confirmed deaths, and one probable death as of 11 June. This brings the combined official total to at least 695 confirmed cases and 138 confirmed deaths, with one additional probable death reported in Uganda.

CDC continues to report no outbreak-associated Ebola cases in the United States and assesses the overall risk to the U.S. public and travelers as low. 

The outbreak is unfolding in a highly complex operating environment: Ituri and surrounding affected provinces face high mobility linked to mining, trade, care-seeking, displacement, and cross-border movement, alongside persistent insecurity, attacks or threats against health infrastructure, and fragile trust in response systems. WHO’s 8 June risk assessment rates the risk in DRC as very high, the risk in Uganda and land-border countries adjoining areas with documented Bundibugyo virus detection as high, and the risk for the rest of the African region and globally as low.

Chronology and current epidemiology

The earliest publicly reported exposure cluster should still be described cautiously, not as a confirmed index case. DRC and WHO reporting indicate that an early signal arose in early May from clusters of severe illness and deaths among health workers and community members in Ituri. Initial testing was negative for Zaire ebolavirus, but further testing by INRB confirmed non-Zaire orthoebolavirus infection, and sequencing identified Bundibugyo virus. DRC officially declared the outbreak on 15 May 2026.

The epidemiologic picture has changed substantially since the 29 May update. WHO reported that by 6 June, DRC cases had been reported from 25 health zones across Ituri, North Kivu, and South Kivu, with Ituri accounting for 94% of confirmed DRC cases. The highest confirmed case numbers reported by WHO at that time were in Bunia, Rwampara, Mongbwalu, and Nyankunde health zones. WHO also reported 5,040 identified contacts under follow-up in DRC, with particularly low 24-hour follow-up performance in Ituri compared with North Kivu and South Kivu.

Uganda’s cases remain epidemiologically linked to transmission originating in DRC. WHO reports that Uganda has documented imported infections and secondary transmission among contacts and health-care workers, but no documented community transmission as of the 8 June update. Kampala and Wakiso are the districts named in WHO reporting.

Clinical features, treatment, and vaccine status

Bundibugyo virus disease is a severe form of Ebola disease. Transmission occurs through direct contact with blood, secretions, organs, or other bodily fluids of infected or deceased people, or with contaminated surfaces and materials. Transmission is amplified when infection prevention and control is inadequate in health-care settings and during unsafe burial practices. The incubation period ranges from two to 21 days, and people are generally not infectious until symptoms appear.

There is currently no licensed or approved vaccine for Bundibugyo virus disease, and there is no FDA-approved or authorized treatment specifically for BVD. The U.S.-licensed Ebola vaccine ERVEBO is indicated for prevention of disease caused by Zaire ebolavirus and should not be assumed to protect against Bundibugyo virus. Treatment therefore remains based on early, high-quality supportive care, including oral and intravenous rehydration, electrolyte management, fever and pain control, treatment of bacterial superinfections or other complications, nutritional support, and careful clinical monitoring.

The countermeasure landscape has changed since the original update. WHO advisory groups now recommend that candidate vaccines and therapeutics be evaluated only within carefully designed clinical trials. For treatment, WHO prioritized MBP134, maftivimab, and remdesivir, including possible combination therapy using a monoclonal antibody with remdesivir. For post-exposure prophylaxis, WHO prioritized obeldesivir for clinical evaluation among contacts of confirmed or probable cases, while noting that this approach depends on effective contact tracing.

For vaccines, WHO identified the single-dose rVSV Bundibugyo candidate under development by IAVI as the most promising candidate, though it may require approximately seven to nine months before it is ready for clinical efficacy assessment. WHO also noted that the ChAdOx1 Bundibugyo candidate under development by Oxford University and the Serum Institute of India could potentially be available for efficacy assessment within two to three months, pending additional animal data. WHO advises that ERVEBO should not be used outside carefully designed research settings for this outbreak.

CEPI has also announced urgent support for three investigational Bundibugyo vaccine candidates: IAVI’s rVSV-based candidate, Moderna’s mRNA-based candidate, and Oxford/Serum Institute’s ChAdOx1-based candidate. This does not change the immediate response priority: until safe and effective products are available, outbreak control depends on surveillance, rapid testing, isolation and care, contact tracing, infection prevention and control, community engagement, and safe and dignified burials.

Context: movement, insecurity, community trust, and response operations

The outbreak continues to occur in a setting where social, mobility, and conflict dynamics are central to transmission risk and response feasibility. Artisanal mining areas, cross-border care-seeking, informal trade, displacement, family networks, and transport corridors all increase the chance that cases and contacts move before they are identified.

Recent official DRC situation reporting highlights operational bottlenecks that should be emphasized more strongly in the brief: weak contact follow-up, community resistance to post-mortem sampling and contact listing, rumors about treatment centers and response teams, laboratory backlogs, insufficient standardized Ebola treatment capacity, infection prevention and control supply gaps, and a funding gap affecting all response pillars. These are not peripheral issues; they directly shape whether transmission chains are detected and interrupted.

Safe and dignified burial remains a major operational and trust priority. Funeral practices such as body washing, touching, mourning gatherings, transport of bodies, prayers, family presence, and burial location are socially and spiritually significant. Safe burial strategies should adapt rituals rather than simply prohibit them, using family consultation, prayers, safe substitutes, photographs or videos where acceptable, and family escort procedures to reduce clandestine burials and resistance.

Risk communication should also explicitly address practical and economic concerns raised by communities, including the quality of care in Ebola treatment centers, costs of care for people who test negative, fear of being deliberately infected, and rumors about response incentives. Community engagement should be treated as an epidemiologic intervention, not only as messaging.

Movement, travel, and border measures

WHO advises against restrictions on travel to, or trade with, DRC or Uganda based on currently available information. WHO instead emphasizes coordinated outbreak control, cross-border collaboration, sustained surveillance, and preparedness.

U.S. authorities have implemented enhanced screening, entry restrictions, and public health measures for affected air passengers from DRC, Uganda, and South Sudan. CDC reports that affected travelers are being routed to designated U.S. airports for screening, even though South Sudan has not reported cases and is included because of shared borders with affected countries. Meanwhile, WHO’s general advice against blanket travel and trade restrictions. 

Conclusion

The 2026 Ebola Bundibugyo outbreak remains a rare and serious public health emergency. Since the original update, confirmed cases have increased substantially, Uganda’s outbreak has remained linked to DRC-origin transmission, and the response has become more clearly defined around three simultaneous needs: interrupting transmission now through proven public health measures, strengthening trust and access in insecure settings, and rapidly evaluating candidate medical countermeasures through ethical clinical trials.

The regional risk is high, particularly for DRC, Uganda, and neighboring land-border countries, while the global risk remains low. The most urgent priorities are not only biomedical but operational and social: fast detection, safe care, reliable contact follow-up, protected health workers, safe and dignified burials, community trust, and sustained financing.