Ebola Virus Disease: Symptoms, Outbreaks, Treatment & Updates

What Changed Since Our Last Review — and What Did Not

Changed (August 5 → September 12, 2026): DRC's confirmed count rose from 4,053 to 7,200 and deaths from 1,850 to 3,475 — about 500–630 new confirmed cases a week, steady rather than accelerating, in our reading of CDC's data file. A sixth province was added. Uganda's outbreak was declared over. WHO reassessed the risk (August 14): very high in DRC, high for bordering countries, low globally. The PHEIC was reaffirmed on August 18. Ervebo vaccination of health workers began August 27 under a research protocol. WHO's PARTNERS treatment trial passed 300 patients. The EU withdrew the Zabdeno/Mvabea vaccine's authorisation (May 1, 2026 — a fact this site had missed until this review).

Not changed: no approved vaccine or treatment for Bundibugyo virus; no case in the United States; CDC's domestic risk assessment of "low"; and — per CDC's own operational review of August 21 — an outbreak whose indicators "indicate uncontrolled expansion." Every figure above has a date and a source on the 2026 outbreak page, which also notes where CDC's and WHO's counts differ.

Six species of orthoebolavirus are recognised; three cause large outbreaks. Every licensed countermeasure — the Ervebo vaccine and the Inmazeb and Ebanga antibody treatments — was built against Ebola (Zaire) virus, which caused every large outbreak before this one. The 2026 outbreak is Bundibugyo virus, a species that had produced only two small outbreaks (Uganda 2007, DRC 2012) before this year. The FDA labels for both antibodies state that efficacy "has not been established for other species"; CDC's clinical guidance (May 27, 2026) says there are no FDA-approved treatments or vaccines for Bundibugyo virus; and WHO's SAGE concluded on August 19, 2026 that Ervebo's efficacy against it "remains unknown."

The species also sets expectations for lethality. A 2024 meta-analysis of 42 outbreaks put the pooled case fatality rate at 66.6% for Zaire virus, 48.5% for Sudan virus and 32.8% (95% CI 25.8–40.2) for Bundibugyo virus (Izudi et al., J Infect Public Health). The 2026 outbreak's crude rate of 48% sits above the Bundibugyo interval — while the 20 confirmed cases treated promptly in Uganda had a fatality rate of 10% (CDC MMWR, September 10, 2026). Whether the gap is timing of care, undetected mild cases, or the virus is not settled. Treatment & vaccines → · Case fatality by species →

Ebola spreads by direct contact with the body fluids of someone who is sick or has died of it — not through the air, and not before symptoms (CDC; WHO). Its reproduction number in 2014 was between 1.7 and 2.0 by country, with a serial interval of about 15 days (WHO Ebola Response Team, NEJM) — lethal, but not especially contagious, and slow enough for contact tracing to work. The transmission-chain data say which precautions matter most: in Guinea, unsafe burial was associated with 1.82 times as many onward infections and treatment-unit care cut onward transmission from patients who died by 38% (Robert et al., Am J Epidemiol 2019); in the 2007 Bundibugyo outbreak, handling the dead without protection carried an adjusted odds ratio of 3.83 (Wamala et al., Emerg Infect Dis 2010). CDC's August 2026 review found only 49% of affected health zones had a safe-burial team and 59% of confirmed deaths were occurring outside a treatment unit. Survivors can carry the virus in semen for many months — 62% of men tested at 4–6 months and 4% at 16–18 months in the Sierra Leone cohort (Deen et al., NEJM 2017). Transmission, with the numbers → · Prevention, with the evidence → · For healthcare workers →

Every figure on this site traces to a primary source read directly, with its date: CDC's situation summary and the public data file behind its outbreak chart; WHO's fortnightly Disease Outbreak News; FDA prescribing information; CDC's MMWR; and peer-reviewed papers cited by DOI. Where CDC and WHO differ — on the sixth affected province, on the 2007 outbreak's case count, on when Uganda's outbreak ended — both are given. Where a number is ours, it is labelled "our calculation" with the arithmetic shown. And where nothing reliable exists, the page says so rather than filling the gap:

• No incubation-period or transmission parameters specific to the 2026 virus have been published in a peer-reviewed primary analysis.
• No result from the PARTNERS treatment trial and no efficacy signal from the Ervebo research-protocol vaccination.
• No current health-worker infection count — WHO last restated it for August 9 (at least 155 cases, 45 deaths).
• No economic-cost estimate for the 2026 outbreak from the World Bank, WHO or CDC.
• No count of Americans under monitoring or tested in 2026 — CDC describes the process, not the numbers.

Compared to what? Ebola is extremely lethal and extremely rare. For how it compares with 14 other viruses on exposure, hospitalisation and death, see the network's Virus Risk Perspective and this site's Ebola risk perspective. Corrections made during this review — eleven of them, from a fever threshold to a withdrawn vaccine authorisation — are on the corrections page and stated on the pages they affect.