History

Discovery of the Virus

Ebola Virus Disease was first identified in 1976 following two nearly simultaneous outbreaks: one caused by the Ebola virus (EBOV) in the Democratic Republic of the Congo (DRC), and the other caused by Sudan virus (SUDV) in Sudan (now South Sudan).

Photo of the team of scientists who studied the 1976 Ebola epidemic in Yambuku (© Dr Joel Breman)

Early Human Transmission

Between the 1980s and 2000s, several epidemics affected Central Africa (Gabon, DRC, Republic of Congo), with a case-fatality rate of around 80%.

Photo of Red Cross members disinfecting a body bag during the 1995 Ebola epidemic in Kikwit, Zaire (Photo credit: US CDC)

West Africa Outbreak

The largest Ebola outbreak to date has mainly affected Guinea, Liberia and Sierra Leone, with over 28,000 cases and 11,000 deaths. This unprecedented outbreak has attracted global attention and prompted a major emergency response.

Photo credit: World Health Organization

First Ebola Vaccine

The WHO announced the demonstrated efficacy of the rVSV-ZEBOV (Ervebo®) vaccine, developed in Canada and produced by Merck*. Its effectiveness was confirmed during the 2015. Since then, the WHO has recommended its use during MVE outbreaks, adopting a vaccination strategy known as ‘ring vaccination’, which involves vaccinating the contacts of confirmed cases, and then the contacts of those contacts, in order to contain the outbreak as effectively as possible and thereby protect the population.¹

Photo credit: World Bank / Vincent Tremeau

Effective Therapeutic Treatment Identified

During the 10th outbreak in the DRC (with more than 3,470 cases and 2,287 deaths), monoclonal antibody treatments were evaluated in the PALM001 trial*. The trial identified two effective treatments for MVE: REGN-EB3 (Inmazeb®), developed by Regeneron Pharmaceuticals, and MAb114 (Ebanga®), developed by the INRB and Ridgeback Biotherapeutics.²

Most Recent Outbreak in Guinea

In 2021, a new epidemic broke out in Guinea, with 23 confirmed cases and 12 deaths, reinforcing the focus on prevention and treatment strategies. The rapid deployment of the rVSV-ZEBOV vaccine and the monitoring of contacts for 21 days (maximum incubation period of the virus) enabled better control of this epidemic.

A potential new treatment

On 15 March 2024, a scientific article published in the journal Science confirmed the efficacy of a broad-spectrum antiviral, obeldesivir (a prodrug of remdesivir) developed by Gilead Sciences, in cynomolgus macaques infected with the Sudan virus. This treatment also showed partial efficacy against the Bundibugyo virus.³

Bundibugyo Ebola outbreak in the DRC and Uganda

The most recent MVE outbreak to date was reported to the WHO on 5 May 2026 in Ituri Province in the Democratic Republic of the Congo, and subsequently also in Uganda. The viral agent is the Bundibugyo virus; this is the third outbreak involving this virus (following two previous outbreaks: in Uganda in 2007–2008 and in the DRC in 2012). The outbreak is still ongoing: as of 18 June 2026, 894 cases had been confirmed, including 204 deaths.

The previous MVE outbreak was also reported in the DRC on 4 September 2025 in the Bulape health zone, in Kasai Province. The outbreak began in August, when a seriously ill pregnant woman went to the hospital in the town’s health zone to give birth by caesarean section, resulting in the infection of around ten people.⁴

Photo of the Bambalaie Ebola Treatment Center, 35 km from Bulape, set up by ALIMA in the Democratic Republic of Congo in 2025. Installation in and near the Bambalaie hospital. Democratic Republic of Congo.

First implementation of the EBO-PEP trial

In response to the Bundibugyo Ebola virus disease outbreak in the DRC and Uganda, the enrolment of participants in the EBO-PEP ODV-BDBV sub-protocol – the first iteration of the EBO-PEP platform trial – will begin in July 2026. The enrolment phase will last two years and will end with the final visit by the last participant in July 2028.

In the Democratic Republic of the Congo, a photograph of the MSF Ebola Treatment Centre supported by ALIMA in Bulape. Democratic Republic of the Congo, 2025.⁵

References

Henao-Restrepo AM, Camacho A, Longini IM, et al. Efficacy and effectiveness of an rVSV-vectored vaccine in preventing Ebola virus disease: final results from the Guinea ring-vaccination trial. Lancet. 2016;389(10068):505–18. DOI:10.1016/S0140-6736(16)32621-6. Photo credit: David Lindsay / Frederick National Laboratory for Cancer Research)
Mulangu S, Dodd LE, Davey RT Jr, et al. A Randomized, Controlled Trial of Ebola Virus Disease Therapeutics. N Engl J Med. 2019;381(24):2293-2303. DOI: 10.1056/NEJMoa1910993. Photo credit: David Lindsay / Frederick National Laboratory for Cancer Research)
Robert W. Cross et al. Oral administration of obeldesivir protects nonhuman primates against Sudan ebolavirus. Science 383, eadk6176(2024). DOI:10.1126/science.adk6176
Tsanni A. Agencies mobilize to stem Ebola epidemic in DRC [Internet]. Nature; 2025 [cited 2025 Nov 27]. Available from: https://www.nature.com/articles/d44148-025-00308-w.
Photo credit: ALIMA