What Happened to Ebola Virus Outbreaks?

Ebola virus disease (EVD), also known as Ebola hemorrhagic fever, first emerged in 1976 with simultaneous outbreaks in Nzara, Sudan, and Yambuku, then Zaire (now the Democratic Republic of Congo), near the Ebola River from which the virus derives its name. Four of the six known ebolavirus species—Bundibugyo, Sudan, Taï Forest, and Zaire—are known to cause disease in humans, with the Zaire ebolavirus being the most dangerous and responsible for the largest number of outbreaks. The virus is zoonotic, believed to originate in fruit bats, and is transmitted to humans through contact with the blood, secretions, organs, or other bodily fluids of infected animals. Human-to-human transmission occurs through direct contact with bodily fluids of an infected person or contaminated objects, with unsafe burial practices often contributing to spread.

The most devastating outbreak occurred in West Africa between 2013 and 2016, primarily affecting Guinea, Liberia, and Sierra Leone. This epidemic resulted in over 28,600 cases and more than 11,300 deaths, becoming the largest and most complex Ebola outbreak in history. The scale of this outbreak highlighted the vulnerabilities of weak public health infrastructures and led to a Public Health Emergency of International Concern (PHEIC) declaration by the World Health Organization (WHO) in August 2014. A key turning point in the fight against Ebola was the accelerated development and eventual approval of vaccines, particularly for the Zaire ebolavirus, such as Ervebo. These vaccines, alongside improved supportive care and rapid response mechanisms, have significantly enhanced the ability to control subsequent outbreaks of the Zaire strain.

Despite these advancements, Ebola outbreaks have continued, particularly in the Democratic Republic of Congo and Uganda. The DRC has experienced numerous outbreaks, including a significant one from 2018-2020, which was the country's largest. Uganda also faced a Sudan ebolavirus outbreak in 2022-2023, which was declared over in January 2023 after infecting over 160 people and causing 77 deaths. The consequences of these outbreaks extend beyond immediate fatalities, with many survivors experiencing long-term health issues known as post-Ebola syndrome.

As of June 17, 2026, a new and rapidly spreading outbreak of the Bundibugyo ebolavirus has been confirmed in the Ituri Province of the Democratic Republic of Congo and has spread to Uganda. This is the 17th Ebola outbreak in the DRC and was declared a PHEIC by the WHO on May 16, 2026. The outbreak is particularly challenging because there are currently no approved vaccines or specific treatments for the Bundibugyo strain. As of June 16, 2026, the DRC reported 808 confirmed cases and 192 deaths, while Uganda reported 19 confirmed cases and two deaths. Response efforts are hampered by insecurity, remote and densely populated areas, and high population movement. In response, the Coalition for Epidemic Preparedness Innovations (CEPI) has fast-tracked funding for three experimental Bundibugyo vaccine candidates from IAVI, Moderna, and Oxford University, with clinical trials expected in the coming months.