DR Congo has confirmed 7,890 cases and 3,799 deaths since 15 May, against 3,470 cases and 2,287 deaths in the whole two-year Kivu epidemic of 2018-20. New cases have stopped accelerating, but they have not yet begun to fall.
DR Congo and Uganda declared an outbreak of Bundibugyo virus disease, a form of Ebola, on 15 May 2026, and WHO declared it a public health emergency of international concern two days later.11 By 23 September DR Congo had reported 7,890 laboratory-confirmed cases, including 3,799 deaths.2 Uganda has reported 20 cases and two deaths, and single imported cases have been treated in France and Germany.1
The natural yardstick is the Ebola outbreak that began in North Kivu on 1 August 2018, the largest in DR Congo's history until now.26 It ran for almost two years, was declared over on 25 June 2020, and recorded 3,470 confirmed and probable cases and 2,287 deaths.7 The US Centers for Disease Control and Prevention (CDC) says the 2026 outbreak passed 1,000 confirmed cases within 40 days of the response starting; the 2018 outbreak took about 235 days.3
At day 77 the Kivu outbreak had 223 cases.8 The 2026 outbreak had 2,124 confirmed cases in DR Congo by day 616 and 6,757 by day 115,1 so it overtook Kivu's final total somewhere in between — within about three months of being declared.
What it is. Ebola is not one virus but a family. Bundibugyo is one of three members known to cause large outbreaks in people; the other two are the Zaire and Sudan species. It is named after Bundibugyo district in western Uganda, where it was first identified in 2007.11 Before this year it had caused only two known outbreaks, in Uganda in 2007 and in DR Congo in 2012, with 131 and 62 confirmed cases respectively.10 The Kivu outbreak of 2018–20 was caused by the Zaire species, a different virus.
Where it comes from. Fruit bats are thought to be the natural home of Ebola viruses. People are usually first infected through contact with the blood or body fluids of an infected animal, such as a bat or a monkey.9 Genetic analysis indicates the 2026 virus is distinct from the 2007 and 2012 strains, which points to a fresh jump from animals rather than a leftover from an earlier outbreak.15
Symptoms. Illness starts 2 to 21 days after infection, usually suddenly: fever, extreme tiredness, muscle pain, headache and sore throat. Vomiting, diarrhoea and a rash tend to follow, and in some patients bleeding, for example from the gums or in the stool.9 The first clusters this year were among health workers in DR Congo, who had fever, vomiting, diarrhoea and in some cases bleeding.4
How it spreads. Between people, the virus passes through direct contact — via broken skin or the eyes, nose and mouth — with the blood, vomit, faeces or other body fluids of someone who is ill or has died, or with bedding and other objects contaminated by them. People are not infectious before their symptoms start. Carers, health workers and people who wash bodies at funerals face the highest risk.9
Treatment. There is no approved drug for Bundibugyo. Care centres on replacing lost fluids and salts and treating symptoms and other infections; improvements in that supportive care have raised survival in recent Ebola outbreaks.10 Since 2 July a WHO-sponsored trial, PARTNERS, has been testing whether an antibody treatment called MBP134 and the antiviral remdesivir, alone or together, improve survival.16 A health worker flown to Germany recovered after receiving both, but a single case cannot show whether the drugs worked.17
Vaccines. None is licensed against Bundibugyo. Since late August DR Congo has been giving Ervebo, the vaccine licensed against the Zaire species, to front-line workers under compassionate-use and research protocols.2819 Animal studies and limited human data suggest it may give some cross-protection.1018 Whether it works against this virus is not yet known.18 Bundibugyo-specific vaccines from Oxford University with the Serum Institute of India, and from Moderna, are in early safety trials.21
Dividing the rise in confirmed cases by the days between reports gives a rough daily rate. It climbed from about 38 a day in June to 86 a day between mid-July and early September, then eased to 71 a day in the first three weeks of September.12 The Kivu outbreak averaged about 12 cases a day between roughly its 1,000th and 2,600th case, its busiest stretch in the figures used here.37
Modelling points the same way. A peer-reviewed analysis estimated early growth at about 9% a day in late May, but warned that the figure was inflated by how quickly cases were being found.12 A preprint, not yet peer reviewed, estimates that each case was infecting about 2.9 others in mid-May and about 1.3 by early July.14 A second preprint puts the national figure close to 1 since early August: roughly, each case now replaces itself rather than multiplying. It also finds that the national average hides continued growth in one North Kivu health zone, and no clear decline in Ituri's two largest towns by case count.13
The outbreak is also still spreading geographically. By 7 September it had reached 61 health zones in six of DR Congo's 26 provinces, with Ituri the epicentre.1 ECDC reports that 83.4% of identified contacts were under follow-up on 23 September;2 the head of Africa CDC has said the response is falling short of the roughly 420,000 contacts that 7,000-plus cases imply.22
WHO puts the crude fatality ratio at 48.3% on 7 September.1 On 23 September figures it is 48.1%. That ratio counts about 2,125 people whose illness had not yet ended in death or recovery. Counting only the 5,765 cases with a known outcome gives 65.9%, the same as the Kivu outbreak's final ratio.27
Neither 2026 measure is the true figure. The crude ratio understates it while many patients are still ill; the known-outcome ratio overstates it if recoveries are recorded more slowly than deaths. A July preprint produced estimates from 37.5% to 67.3% from the same data depending on the method.14 The Kivu ratio is not a clean comparison either, because probable cases are identified largely after death, which pushes it up.
Young children fare worst. WHO's Africa office reports that children make up nearly one in four confirmed cases but almost one in three deaths, and that more than 60% of confirmed cases in children under five have died.18
These are the explanations offered in the research so far; none has been tested as a cause. First, detection: a preprint estimates transmission began around 19 April, 16 days before WHO was alerted,15 and the first suspected case was a health worker, with at least four health workers dead before the outbreak was confirmed.27 Second, tools: responders in Kivu had a vaccine matched to the virus, eventually given to more than 320,000 people,23 and trial-proven antibody treatments that WHO has since recommended.25 In 2026 neither existed at the start. Third, setting: this is the first Bundibugyo outbreak to sustain spread in a major city, Bunia,15 and it is unfolding in a region of armed conflict and mass displacement.27
The true size of the outbreak. Confirmed counts depend on testing. An early jump in reported cases coincided with the clearing of a backlog of samples,10 and a preprint argues that a flat count alongside a rising death ratio in early July fits laboratories running at capacity rather than slower spread.14
Whether the levelling-off is real. The national reproduction number near 1 comes from a preprint that has not been peer reviewed, and it masks local growth.13
Whether Ervebo protects against Bundibugyo. A 20,000-person study, BRAVO, began in Bunia on 19 September and is expected to run for nine to 12 months.20 No results from the PARTNERS treatment trial have been published.16