Major Outbreaks Timeline
Key Ebola outbreaks from first discovery to the present active outbreak.
- 1976
First Identified Outbreaks — Sudan & DRC
Two simultaneous outbreaks in 1976: Nzara, Sudan (Sudan virus — 284 cases, 151 deaths, 53%) and Yambuku, DRC near the Ebola River (Ebola virus — 318 cases, 280 deaths, 88%), per CDC. The virus was named after the Ebola River. In Yambuku the index case was treated at the mission hospital with an injection for possible malaria, and CDC records that transmission then followed the reuse of needles and syringes and close personal contact — only 38 serologically confirmed survivors were identified. In Sudan the outbreak began among workers at a cotton factory and spread mainly within hospitals. A third 1976 case was a laboratory needle-stick infection in the United Kingdom; the worker survived.
- 1989
Reston, Virginia — Ebola Reston in Non-Human Primates
Reston virus was discovered in macaques imported from the Philippines to primate-holding facilities in Reston, Virginia, and also Philadelphia and Alice, Texas. Per CDC, four people developed antibodies but never experienced symptoms; the same export facility later seeded episodes in Italy (1992) and Texas (1996), again with no human illness. Reston virus is the one orthoebolavirus known to infect people without causing disease. It was the first Ebola virus identified outside Africa, and the subject of The Hot Zone.
- 1995
Kikwit, DRC
A major outbreak of Ebola virus in Kikwit, DRC resulted in 315 cases and 254 deaths (81%), per CDC. It began with a charcoal maker in the forest near the city and spread through families and hospitals; CDC notes that transmission in the healthcare setting "was halted almost immediately" once masks, gloves and gowns were used. Kikwit also produced the dataset behind the best estimate of Ebola's incubation distribution: a mean of 12.7 days (SD 4.31), implying about 4.1% of cases incubate longer than the standard 21-day monitoring window (Eichner et al., 2011).
- 2000–2001
Gulu, Uganda — Sudan Ebolavirus
An outbreak of Sudan virus starting in Gulu, Uganda resulted in 425 cases and 224 deaths (53%), per CDC — the largest Sudan virus outbreak ever recorded, later spreading to Masindi and Mbarara districts. Healthcare facilities were a major amplification site. CDC credits community action, local government support and "correct and timely messaging" to limit harmful rumors — the same three levers the 2026 response is struggling with.
- 2007
Bundibugyo, Uganda — New Species
An outbreak in Bundibugyo District, western Uganda, from August 2007 to February 2008 led to the discovery of a new species, Bundibugyo virus (Towner et al., PLoS Pathogens 2008). It is the species now driving the far larger 2026 DRC outbreak. Its case count and fatality rate depend on which source you read: CDC's history page gives 131 cases and 42 deaths (32%); the WHO Disease Outbreak News for 2026 gives 30%; the outbreak investigation by Wamala et al. (Emerging Infectious Diseases 2010) found 42 laboratory-positive and 74 probable cases with a fatality rate of 34%; and the clinical series by Roddy et al. (2012) counts 93 putative cases, 56 confirmed, 37 deaths and 25%. The spread comes from whether probable cases are counted and which deaths are attributed. Laboratory confirmation lagged outbreak verification by three months, and most transmission was linked to handling the dead without protection (adjusted odds ratio 3.83, 95% CI 1.78–8.23, Wamala et al.).
- 2014–2016
West Africa Epidemic — Largest in History
The largest Ebola outbreak in history spread across Guinea, Liberia, and Sierra Leone, with exported cases in Nigeria (20 cases, 8 deaths), Mali (8, 6), Senegal (1, 0), the United States (4 diagnosed, 1 death), the UK, Spain and Italy (1 each, no deaths). CDC's tally is 28,610 cases and 11,308 deaths (39%) in the three most affected countries; WHO's final situation reports give 28,616 and 11,310. The crude 39% understates the lethality — among patients with a known outcome in the first nine months, 70.8% died (95% CI 69–73; WHO Ebola Response Team, NEJM 2014), and the gap is unrecorded outcomes, not survival. The epidemic produced the Guinea ring-vaccination trial that led to Ervebo and the semen-persistence studies that changed survivor guidance. It was declared over in June 2016.
- 2018–2020
DRC — North Kivu & Ituri (Zaire ebolavirus)
DRC's 10th outbreak, declared August 1, 2018 in North Kivu and later reaching Ituri, South Kivu and Uganda. CDC records 3,470 cases and 2,287 deaths (66%), noting that four cases confirmed in Uganda in 2019 were recorded in both countries and died in DRC; WHO's final figures are 3,481 cases (3,323 confirmed, 158 probable) and 2,299 deaths. It was the second-largest outbreak in history until 2026 surpassed it in July. The response was severely complicated by armed conflict and community mistrust. Ervebo was used at scale under a compassionate-use protocol, and the PALM trial run inside this outbreak (681 patients, November 2018–August 2019) produced the two antibody treatments now approved for Ebola virus (Mulangu et al., NEJM 2019). It was declared over June 25, 2020.
- 2021
DRC — Guinea Resurgence
Three small Ebola virus outbreaks: DRC North Kivu in February–May (12 cases, 6 deaths), Guinea in February–June (23 cases, 12 deaths, 52.2%) — Guinea's first since 2016 — and DRC North Kivu again in October–December (11 cases, 9 deaths). All three were rapidly contained. Per CDC, sequencing linked the Guinea outbreak and both DRC outbreaks to earlier epidemics rather than to new animal spillovers, most likely through persistent infection in a survivor leading to relapse or sexual transmission. These were the outbreaks that established survivor persistence as a route by which Ebola can re-emerge years later.
- 2022–2023
Uganda — Sudan Ebolavirus
Correction, published September 14, 2026. Earlier versions of this timeline gave Uganda's 2022 outbreak as "164 confirmed cases" with 77 deaths, mixing confirmed with probable cases in one count and probable deaths into the other; gave the 2018–20 DRC outbreak only WHO's total without CDC's; and gave a single figure for the 2007 Bundibugyo outbreak where four published counts exist. Each entry now states the source of every number. Logged on our corrections page.An outbreak of Sudan virus confirmed in Mubende District on September 20, 2022 — Uganda's sixth Ebola outbreak, five of them Sudan virus. CDC's final figures are 142 confirmed and 22 probable cases (164 in all) and 55 confirmed deaths (34% of all cases); adding the 22 probable deaths gives the 77 often quoted. No licensed vaccine existed for Sudan virus — Ervebo only covers Ebola virus — and candidate Sudan vaccines arrived for a ring trial only as the outbreak ended. It was declared over on January 11, 2023. A smaller Sudan virus outbreak followed in Kampala in January 2025 (12 confirmed and 2 probable cases, 4 deaths), declared over April 26, 2025.
- 2025
DRC — Kasai Province (Ebola virus)
DRC's 16th outbreak, declared September 4, 2025 in the remote Bulape health zone of Kasai Province after the national laboratory (INRB) confirmed Ebola virus on September 3. Per CDC it ended on December 1, 2025 with 53 confirmed and 11 probable cases and 45 deaths (70%). It was the last outbreak before the 2026 Bundibugyo emergency, and — unlike 2026 — the species was one for which a vaccine and two treatments existed.
- 2026
DRC — Bundibugyo Virus (Second Largest Ever) Active
Declared May 15, 2026, DRC's 17th Ebola outbreak — caused by Bundibugyo virus, an established species (not a novel one) that had produced only the two small outbreaks above. WHO was alerted on May 5 to a cluster of deaths of unknown cause in Mongbwalu health zone, Ituri; the national laboratory confirmed Bundibugyo virus in 8 of 13 samples on May 15 (WHO DON 602), and a later reconstruction put the earliest symptom onset at April 24 (Elvis Akem et al., 2026). It is now the second-largest Ebola outbreak on record and the largest ever in DRC: 7,200 confirmed cases and 3,475 deaths as of September 12, 2026 (CDC; crude CFR 48%), in six provinces and 61 health zones (WHO DON 617). A WHO Public Health Emergency of International Concern was declared May 17, 2026 and reaffirmed August 18. Because the licensed Ebola vaccines and treatments target Ebola (Zaire) virus, none is approved for Bundibugyo virus. Uganda's linked outbreak (20 confirmed cases, 2 deaths) was declared over — on July 28 according to WHO's Disease Outbreak News 614, or August 26 according to CDC's MMWR report on the Ugandan cases; the two agencies date the end differently. See full outbreak details, updated with each CDC and WHO report →
How Fast Each Big Outbreak Grew — CDC's Day-by-Day Comparison
CDC's situation page carries a chart comparing the first 180 days of the three largest outbreaks. The data file behind it is public; the table below is read from it directly.
| Days since first reported case | West Africa 2014 (Ebola virus) | DRC 2018 (Ebola virus) | DRC 2026 (Bundibugyo virus) |
|---|---|---|---|
| Day 28 | 230 | 96 | 676 |
| Day 42 | 234 | 118 | 1,155 |
| Day 60 | 270 | 143 | 1,963 |
| Day 90 | 528 | 271 | 4,566 |
| Day 120 | 1,048 | 436 | 7,022 |
| Day 122 (latest for 2026) | 1,093 | 438 | 7,200 |
| Day 180 | 5,325 | 741 | — |
| First day at ≥1,000 cases | Day 119 | Not within 180 days | Day 38 |
| First day at ≥4,000 cases | Day 168 | — | Day 84 |
At the same point in its course, the 2026 outbreak had reported 6.6 times as many cases as the 2014 epidemic and 16 times as many as the 2018 outbreak (our calculation: 7,200 ÷ 1,093 and 7,200 ÷ 438). Part of that is real speed; part is that 2026 is being counted by a laboratory network that did not exist in Guinea in 2014 — WHO's reports repeatedly attribute some of each fortnight's rise to "strengthened surveillance… and reconciliation of previously unreported data" (DON 617). The two effects cannot be separated from the published numbers. What can be said is that West Africa's curve turned upward after day 120 and reached 28,600, and that the 2026 outbreak had not yet turned downward at day 122.
Outbreaks by Species — and Why Bundibugyo Was the "Milder" One Until 2026
Six species of orthoebolavirus are recognised. Four infect people; three of those have caused large outbreaks. CDC's history page summarises their lethality in round terms; the pooled figures from Izudi et al.'s 2024 meta-analysis of 42 outbreaks give the intervals.
| Virus (species) | Human outbreaks | CDC's summary | Pooled CFR, 1976–2022 (95% CI) |
|---|---|---|---|
| Ebola virus (Orthoebolavirus zairense) | Most large outbreaks: 1976 Yambuku, 1995 Kikwit, 2014–16 West Africa, 2018–20 DRC, 2025 Kasai | "up to 90% of cases are fatal" without treatment | 66.6% (55.9–76.8) |
| Sudan virus (O. sudanense) | 1976 and 1979 Sudan; 2000 Gulu, 2011, 2012, 2022 and 2025 Uganda | "about 50%" | 48.5% (38.6–58.4) |
| Bundibugyo virus (O. bundibugyoense) | 2007 Uganda; 2012 DRC; 2026 DRC and Uganda | "about 30%" | 32.8% (25.8–40.2) |
| Taï Forest virus (O. taiense) | One case, Côte d'Ivoire 1994 (survived) | "rarer cause of disease" | 0% (0–97.5) |
| Reston virus (O. restonense) | Antibodies in animal-facility workers (US 1989, Philippines 1989 and 2008); no illness | "does not cause illness in people" | — |
| Bombali virus (O. bombaliense) | Identified in bats; no human infection recorded | — | — |
Before 2026, Bundibugyo virus was known from 131–149 cases in Uganda and 57–62 in DRC, depending on the source. The 2026 outbreak has produced more than thirty times that combined total in four months, at a crude fatality rate of 48% — above the upper bound of the historical interval. Whether that reflects the virus, the conflict-affected setting, or how cases are being counted is not yet established; the symptoms page lays out the three candidate explanations with the numbers behind each. Compared to what? For Ebola alongside 14 other viruses, see the Virus Risk Perspective and this site's Ebola risk perspective.
Why CDC and WHO Publish Different Totals for the Same Outbreak
Readers comparing CDC with WHO will find small, persistent gaps: 28,610 (CDC) versus 28,616 (WHO) cases for West Africa; 3,470 versus 3,481 for the 2018–20 DRC outbreak; 55 versus 77 deaths for Uganda 2022. None of these is an error. They arise from three counting choices that each agency makes differently and states in its footnotes:
- Probable and suspected cases. WHO totals typically include probable cases (clinically compatible, epidemiologically linked, never laboratory-confirmed); CDC's per-outbreak entries sometimes report confirmed cases only, and say so. In 2026 the DRC Ministry of Health does not include probable cases in its official count and has temporarily excluded suspected cases and deaths "pending ongoing investigations and data standardization" (CDC, September 2026).
- Cross-border attribution. CDC's 2018–20 footnote explains that four cases confirmed in Uganda were recorded in both countries and died in DRC.
- Reconciliation after the fact. Final tallies are revised for months after an outbreak ends as cases are reclassified. The 2007 Bundibugyo outbreak still has four published case counts.
Our practice on this site is to give CDC's figure first and WHO's alongside it where they differ, rather than pick one and present it as the number.
Why DRC Counts Its Outbreaks — the Seventeen
News reports describe the 2026 emergency as DRC's "17th outbreak." The numbering is the Ministry of Health's and counts each declared outbreak on Congolese territory since Yambuku in 1976, regardless of size or species. From CDC's history page the sequence runs: 1976 Yambuku; 1977 Tandala (a single retrospective case); 1995 Kikwit; 2007 Kasai Occidental; 2008 Kasai Occidental; 2012 Isiro (Bundibugyo virus); 2014 Boende, Équateur — unrelated to the simultaneous West African epidemic; 2017 Likati, Bas-Uélé; 2018 Bikoro, Équateur (9th); 2018–20 North Kivu (10th); 2020 Mbandaka, Équateur (11th); 2021 Biena, North Kivu (12th); 2021 Beni, North Kivu (13th); 2022 Mbandaka (14th); 2022 Beni (15th); 2025 Bulape, Kasai (16th); 2026 Ituri (17th). Every one of the first sixteen was Ebola virus except Isiro in 2012 — which makes 2026 only the second Bundibugyo outbreak in the country's history and the first large one anywhere.
The reason so many occur in DRC is partly ecological — the suspected fruit-bat reservoir lives in its equatorial forest — and partly a matter of detection: the national laboratory, INRB, has confirmed every recent outbreak within days of samples arriving, which means small clusters are recognised in DRC that might go unnamed elsewhere. In 2026 the interval from the earliest reconstructed symptom onset (April 24) to laboratory detection (May 14) was 20 days (Elvis Akem et al., PLOS Global Public Health 2026) — the delay that gave the outbreak its head start.
Frequently Asked Questions
When was Ebola first discovered?
Ebola was first identified in 1976 during two simultaneous outbreaks: one near the Ebola River in Yambuku, DRC (Ebola virus — 318 cases, 280 deaths, 88%) and one in Nzara, Sudan (Sudan virus — 284 cases, 151 deaths, 53%), per CDC. The virus was named after the Ebola River in DRC. Bundibugyo virus, the species behind the 2026 outbreak, was not discovered until 2007 (Towner et al., 2008).
What was the largest Ebola outbreak?
The 2014–16 West Africa epidemic was the largest in history: 28,610 cases and 11,308 deaths per CDC (28,616 and 11,310 per WHO) across Guinea, Liberia, and Sierra Leone, with exported cases on three continents. The 2026 DRC Bundibugyo outbreak is the second-largest — 7,200 confirmed cases and 3,475 deaths as of September 12, 2026 (CDC) — and is growing faster than West Africa did at the same stage.
Why do most Ebola outbreaks occur in DRC?
The Democratic Republic of Congo has experienced more Ebola outbreaks than any other country for several reasons: the presence of the natural animal reservoir (fruit bats) in dense equatorial forest; cultural practices involving bushmeat; weak healthcare infrastructure; and in eastern DRC, ongoing armed conflict that disrupts outbreak response. The DRC also has some of the world's best tropical disease surveillance and response capacity, partly because of this history — meaning outbreaks there may be detected sooner than in other settings.
Sources & References
- Centers for Disease Control and Prevention. History of Ebola Outbreaks. Reviewed May 29, 2026. cdc.gov/ebola/outbreaks
- Centers for Disease Control and Prevention. Ebola Outbreak: Current Situation (including the chart data file "Cases in the first six months of Ebola outbreaks, 2014–2026"). Page dated September 14, 2026. cdc.gov/ebola/situation-summary
- Centers for Disease Control and Prevention. Ebola Disease Basics. June 2, 2026. cdc.gov/ebola/about
- World Health Organization. Disease Outbreak News 602 (May 17, 2026) and 617 (September 10, 2026): Ebola disease caused by Bundibugyo virus. who.int/…/2026-DON617
- Towner JS, et al. Newly discovered Ebola virus associated with hemorrhagic fever outbreak in Uganda. PLoS Pathog 2008;4(11):e1000212. doi:10.1371/journal.ppat.1000212
- Wamala JF, et al. Ebola hemorrhagic fever associated with novel virus strain, Uganda, 2007–2008. Emerg Infect Dis 2010;16(7):1087–92. doi:10.3201/eid1607.091525
- Roddy P, et al. Clinical manifestations and case management of Ebola haemorrhagic fever caused by a newly identified virus strain, Bundibugyo, Uganda, 2007–2008. PLoS One 2012;7(12):e52986. doi:10.1371/journal.pone.0052986
- WHO Ebola Response Team. Ebola virus disease in West Africa — the first 9 months of the epidemic and forward projections. N Engl J Med 2014;371:1481–95. doi:10.1056/NEJMoa1411100
- Eichner M, Dowell SF, Firese N. Incubation period of Ebola hemorrhagic virus subtype Zaire. Osong Public Health Res Perspect 2011;2(1):3–7. doi:10.1016/j.phrp.2011.04.001
- Mulangu S, et al. A Randomized, Controlled Trial of Ebola Virus Disease Therapeutics. N Engl J Med 2019;381:2293–303. doi:10.1056/NEJMoa1910993
- Izudi J, Bajunirwe F. Case fatality rate for Ebola disease, 1976–2022: A meta-analysis of global data. J Infect Public Health 2024;17(1):25–34. doi:10.1016/j.jiph.2023.10.020
- Elvis Akem T, et al. Operational epidemiology of the early phase of the 2026 Bundibugyo virus disease outbreak. PLOS Glob Public Health 2026;6(8):e0006680. doi:10.1371/journal.pgph.0006680
