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Toppage > Infectious Disease > Ebola virus disease > risk-assessment > Outbreak of Ebola Disease caused by Bundibugyo virus in the Democratic Republic of the Congo and Uganda

Outbreak of Ebola Disease caused by Bundibugyo virus in the Democratic Republic of the Congo and Uganda

This document contains information based on official documents released by domestic and international health organizations and research institutions. Accordingly, information disclosed through press conferences or similar public briefings is not included.
Information may have largely evolved since the time of publication, as investigations by domestic and international health agencies and researchers are ongoing. Readers are advised to verify the most recent official information.


Japan Institute for Health Security

May 18, 2026

Overview

On 15 May 2026, the Africa Centres for Disease Control and Prevention (Africa CDC) announced an outbreak of Ebola disease in Ituri Province of the Democratic Republic of the Congo (DRC). On 17 May, the World Health Organization (WHO) declared that the event constituted a Public Health Emergency of International Concern (PHEIC), while noting that it did not meet the criteria for a pandemic emergency.

According to WHO, as of 16 May, a total of eight confirmed cases and 246 suspected cases, including 80 deaths, has been reported across three health zones: Bunia, Rwampara, and Mongbwalu. Polymerase chain reaction (PCR) testing conducted by the Institut national de recherche biomédicale (INRB) detected orthoebolavirus in 13 of 20 specimens tested, and genomic analysis confirmed the virus as Bundibugyo virus. In addition, two cases imported from the DRC, including one death, were identified in Kampala, the capital city of Uganda. However, no evidence of onward transmission within Uganda has been confirmed at present.

 

This event is the 17th Ebola disease outbreak in the DRC. The previous outbreak, caused by Zaire ebolavirus in Kasai Province, declared in September 2025 and was declared over in December 2025. In northeastern DRC, a major outbreak also occurred in North Kivu Province, which borders Ituri, between August 2018 and June 2020. Cases were also identified in South Kivu Province and Uganda in this outbreak, and WHO declared a PHEIC in July 2019.

The current outbreak is the third outbreak of Ebola disease caused by Bundibugyo virus, following outbreaks in Uganda during 2007–2008 and in the DRC in 2012.

 

Ebola disease is transmitted through direct contact with the blood, bodily fluids, or contaminated materials of infected or deceased individuals. Accordingly, immediate patient isolation, contact tracing, infection prevention and control measures in healthcare settings, risk communication with affected communities, and safe and dignified burial practices are essential.

Although public health response measures led by the government of the DRC, WHO, Africa CDC, and partner organizations are underway, it has been reported that contact tracing and epidemiological investigations remain insufficient because of ongoing security challenges and the high mobility of populations in affected urban areas.

Bundibugyo Virus

Bundibugyo virus is a non-segmented, negative-sense single-stranded RNA virus belonging to the genus Orthoebolavirus, family Filoviridae. The genus Orthoebolavirus comprises six species in total: Bundibugyo, Zaire, Sudan, Taï Forest, Reston, and Bombali virus.

Note: Diseases caused by the genus Orthoebolavirus are increasingly referred to using the specific virus name followed by “disease” (e.g., Sudan virus disease, Bundibugyo virus disease). Meanwhile, under Japan’s Infectious Diseases Control Law, these diseases are collectively classified as “Ebola hemorrhagic fever.”

 

At present, no vaccines or monoclonal antibody therapeutics specifically against Bundibugyo virus have been approved for practical use. Although vaccines and antibody-based therapeutics targeting Zaire virus have been developed and deployed, their effectiveness against Bundibugyo virus is known to be limited.

Risk Assessment

  • The affected area in the DRC is located near the borders with Uganda and South Sudan. There is population movement associated with mining activities and security constraints, and there have been reports of challenges related to case finding, contact tracing, and infection prevention and control measures. In addition, a substantial number of reported suspected cases have not undergone laboratory testing. As uncertainty remains regarding the actual number of cases and the geographical extent of the outbreak, continued close monitoring of the situation is warranted.
  • The cases currently reported from Uganda are considered to be imported cases exposed in the DRC, and no onward transmission within Uganda has been confirmed to date. However, difficulties in contact tracing, together with active cross-border population movement, suggest that there is a high risk of further spread to neighboring countries sharing borders with the DRC.
  • The outbreak has primarily been reported in Ituri Province, which is geographically distant from the capital of the DRC and is affected by ongoing conflict. Direct travel and population movement between the affected area and Japan are therefore limited. Based on the information currently available, the likelihood of importation of cases or the risk of onward transmission within Japan, is considered to be low. Accordingly, the risk of infection among the general public in Japan is considered to be low.

Relevant information

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