The Bundibugyo virus outbreak in the eastern Democratic Republic of the Congo is still growing. As of June 6, the U.S. Centers for Disease Control and Prevention counts 515 confirmed cases and 91 confirmed deaths in the DRC. As of June 5, it counts another 19 confirmed cases and two deaths across the border in Uganda — a regional total of 534 cases and 93 deaths.
The trajectory is the story, and it holds on a like-for-like read. When the CDC and the DRC and Ugandan health ministries first described the outbreak in an MMWR Notes from the Field, the DRC’s confirmed count stood at 363 cases and 62 deaths as of June 2, part of a region-wide total of 378 cases and 63 deaths. Four days later, the DRC count had climbed to 515. The European Centre for Disease Prevention and Control (ECDC), working from a slightly earlier Ministry of Health update, recorded 381 DRC cases and 64 deaths as of June 3 and flagged “18 new confirmed cases and 2 new deaths” reported on a single day. The numbers are still moving in one direction.
This is a hard pathogen to fight. Bundibugyo is one of four orthoebolaviruses that cause Ebola disease in humans, and the CDC is blunt about the toolkit: “There is no vaccine for Bundibugyo virus, and treatment consists of supportive care.” The rVSV-ZEBOV vaccine and the monoclonal-antibody therapeutics that reshaped responses to Zaire ebolavirus do not target this species. The MMWR authors put the broader uncertainty plainly.
“The scope of the outbreak is likely larger than that represented by available data and might prove challenging to contain and control.” — MMWR, Notes from the Field
Where it is, and where it has gone
The DRC epicenter is Ituri province, which ECDC mapped at 359 confirmed cases across 17 health zones, with smaller clusters in North Kivu (19 cases) and South Kivu (3 cases). Describing the early case mix, the MMWR reported cases primarily among adults aged 18 to 49, roughly evenly split between women and men, with initial clusters among health care workers — the signature of a pathogen amplifying inside the health system itself. As the DRC caseload has grown, that profile has shifted: the CDC’s current page says most DRC cases are now in people aged 20 to 39, and “two-thirds have been in female patients.”
The cross-border spread is what raises the regional stakes. Uganda’s cases, per the MMWR, “primarily involved travelers arriving from DRC, with secondary transmission to health care workers.” ECDC reports that of the 19 Ugandan cases, eight with known geographic information were in the capital, Kampala, plus one in the neighboring district of Wakiso. Urban transmission in a capital city is a different containment problem than rural Ituri.
The data itself has been turbulent. CIDRAP reported that the WHO and the U.S. CDC sharply revised an early figure of nearly 1,000 cases down to 321 confirmed cases across the DRC and Uganda — a reminder that suspected and confirmed counts diverge widely early in an Ebola response, and that the surveillance picture has shifted as case definitions firmed up.
The case-fatality rate computed from the CDC’s latest figures is about 17.4% region-wide — below the 25% to 90% range historically seen across Ebola species, though early case-fatality rates understate the eventual toll because recent cases have not yet resolved. The CDC assesses the risk to the U.S. public as low; one American health care worker who tested positive on May 17 after caring for patients in the DRC is in stable condition in Germany. ECDC likewise rates the likelihood of infection for people in the EU/EEA as “very low.”
What the surveillance does not yet show is a peak. With no countermeasures licensed against Bundibugyo, the response rests on the oldest tools in outbreak control: case finding, isolation, contact tracing, and safe burials — against a virus the MMWR warns may already be more widespread than the line lists suggest.