As of May 22, over 800 Ebola cases have been reported in the Democratic Republic of the Congo, including more than 180 deaths; these counts include both suspected and laboratory-confirmed cases of the disease. There are also two confirmed cases and one death in Uganda, specifically among people who had recently traveled to the DRC.
A number of factors are making this outbreak very challenging to contain, experts told Live Science — here's what to know.
Current Ebola outbreak
WHO officials suspect the Ebola outbreak centered in the DRC may have begun about two months ago. The earliest suspected death occurred April 20, and it was likely followed by a superspreader event at a funeral or healthcare facility, officials say. Reuters also reported that medical personnel failed to escalate the first patient's samples for further tests after they came back negative one type of ebolavirus.
That virus — known as Ebola virus, or Zaire ebolavirus — is the most common culprit behind Ebola disease outbreaks and deaths. There are two other viruses known to cause outbreaks of Ebola disease: Sudan virus and Bundibugyo virus. The latter is driving the current outbreak.
With only a handful of travel-related cases in Uganda, as well as one American receiving care in Germany after being infected in Congo, the outbreak remains concentrated in the DRC. The WHO anticipates a high risk of international spread, though, which prompted the agency's leader to make an emergency declaration without first convening a committee to discuss the decision.
"In our view, the scale and speed of the epidemic demanded urgent action," WHO Director-General Tedros Adhanom Ghebreyesus said May 19.
Sign up for the Live Science daily newsletter now
Get the world’s most fascinating discoveries delivered straight to your inbox.
A virus with no vaccine
Part of the challenge with containment is that there is no effective vaccine against Bundibugyo virus, the germ driving this outbreak.
There are approved Ebola vaccines. "However, these vaccines have been designed specifically to address the Zaire ebolavirus," which has historically caused more outbreaks than Bundibugyo virus has, said Dr. Madeline DiLorenzo, clinical coordinator of infectious diseases operations and an associate hospital epidemiologist at New York University (NYU) Langone's Tisch Hospital. The largest Ebola outbreak to date, which happened from 2014 to 2016, involved the Zaire ebolavirus.
Zaire ebolavirus and Bundibugyo virus are genetically distinct, sharing only about 60% to 70% of their genetic material. The protein targeted by the existing Ebola vaccines is encoded by a specific gene, and that gene's sequence differs between the two viruses, DiLorenzo explained.
Studies suggest that immune responses against filoviruses — the family of viruses that includes Zaire ebolavirus and Bundibugyo virus — show limited cross-reactivity, meaning the immune response is narrowly focused on just one type of virus. So the Zaire-targeting vaccines likely wouldn't help in this outbreak.
Currently, there is no effective vaccine for Bundibugyo virus.
(Image credit: Shutterstock)
WHO officials have said there is a promising experimental vaccine against Bundibugyo virus, but there are no doses available for a clinical trial. It could take six to nine months to manufacture those doses, the WHO estimates. Another vaccine in development could take two to three months to produce, but its efficacy is unknown because scientists are still waiting on results from lab-animal tests.
In Ebola disease outbreaks, vaccines are used for ring vaccination, in which people exposed to a suspected or confirmed case are inoculated against the disease. They can also be used for "targeted geographic vaccination," in which everyone in a given area is vaccinated because the outbreak is relatively concentrated there or contact tracing is too difficult to conduct. Without a Bundibugyo vaccine, both of those strategies are currently off the table.
Lack of diagnostics and treatments
Ebola disease can be difficult to spot in its early stages, in part because the first symptoms are fairly generic: fever, fatigue, malaise, muscle pain, headache and sore throat. These symptoms appear within two to 21 days of exposure to an ebolavirus.
There are tests for Bundibugyo virus that look for the virus's genetic material in bodily fluids; this approach is known as PCR testing. "However, it is not widely available for the Bundibugyo virus, making it difficult to diagnose and, as a result, contain the virus," Dr. Jill Weatherhead, an associate professor of infectious disease and tropical medicine at Baylor College of Medicine, told Live Science in an email.
Even when such tests are available, it can take several days after a patient develops symptoms for the virus to be detectable in blood, DiLorenzo noted, so repeat testing can be necessary. The recommended samples for Ebola tests are whole blood or plasma for living patients and an oral swab for deceased individuals, the WHO says.
There are additional tests that can detect Bundibugyo virus, including some that determine whether a sample contains a filovirus that infects humans in general, without specifying which one is present. These rapid tests look for specific viral proteins. However, these tests are less sensitive and "may not pick up specific proteins associated with Bundibugyo," DiLorenzo said. "This may have contributed to delayed detection of the current outbreak in the DRC."
In the current outbreak, the WHO says the risk of spread is "very high at the national level, high at the regional level, and low at the global level."
(Image credit: Michel Lunanga / Stringer via Getty Images)
On top of these diagnostic challenges, there are no specific antiviral treatments for Bundibugyo virus. There are lab-made antibodies approved for Zaire ebolavirus, and they improve survival by binding to the virus's surface and blocking it from infecting cells. Similar treatments for Bundibugyo virus haven't progressed beyond lab research or early-stage human safety studies, Weatherhead said.
Conflict, declining foreign aid hinder containment
In the absence of vaccines and treatments, other strategies, such as quarantining close contacts of infected people, become key to containing the outbreak, Weatherhead said. Clinicians treating patients with suspected or known cases should also follow strict infection-prevention-and-control protocols to prevent further spread, she added.
Ebola spreads via contact with infected blood and other bodily fluids, as well as contaminated surfaces or materials, such as clothing and bedding. This means using personal protective equipment to block splashes or other contact with infected materials, among other protocols.
The strategies available to contain this outbreak — finding and isolating cases and employing tight infection-control protocols — require public health infrastructure to execute. But in the DRC, that infrastructure is severely compromised. The outbreak's epicenter is the Ituri province in the northeastern DRC, which has "experienced armed conflict for decades, making it challenging for health systems to function optimally there," DiLorenzo said.
Joshua Walker, director of programs of the Congo Research Group at NYU's Center on International Cooperation, told Live Science via email that the circumstances of the current outbreak resemble a 2018-2020 outbreak that centered on the North Kivu province, which borders Ituri to the south.
Funding cuts directly do not cause outbreaks, but they do weaken the very systems that are meant to prevent small crises from becoming larger crises.
Dr. Manenji Mangundu, DRC country director for Oxfam
This time around, several cases have been reported in both North and South Kivu provinces, parts of which are essentially partitioned between the DRC government and a Rwanda-backed rebel group, called M23. And there's been increasing violence among armed groups in Ituri in recent months, Walker said. Meanwhile, development assistance for healthcare in the area has fallen substantially in recent years. Together, these factors "will make access and coordination of a single response more difficult," he said.
"USAID [the U.S. Agency for International Development] was the main donor in the DRC and many aid organizations depended on its funding to deliver life-saving support in a country already devastated by conflict," Mangundu said. "When USAID was shuttered last year, eastern DRC lost around 70% of its humanitarian aid."
More funding cuts from other donors followed, leading to the closure of medical centers, declines in medical supplies and community health workers, and reduced capacity to deal with outbreaks.
"Funding cuts directly do not cause outbreaks, but they do weaken the very systems that are meant to prevent small crises from becoming larger crises," Mangundu said.
In Ituri, residents have been repeatedly displaced due to the conflict and must shelter in crowded schools and churches with limited access to clean water, sanitation and healthcare. Funding cuts only compound these existing problems, he said.
In this setting, it can also be difficult to convince people to adopt safety measures to limit the spread of Ebola, he added. For example, "communities remain attached to their deceased relatives and continue to handle the bodies, which increases the risk of transmission."
Lessons from past outbreaks
Walker noted that the international response to the current outbreak will shape how it evolves.
"The 2018-2020 Ebola response effectively sidelined the local Congolese health system, viewing it as too fragile or weak to be an effective partner," he said, citing hispast research. So the response was largely orchestrated by outsiders to local communities, which fostered suspicion.
"There is capacity in the country to respond, but there are not enough resources to help control and prevent the spread," he said. "We need to fund humanitarian aid and support the people of DRC at this time before a preventable crisis turns into one with far wider, global consequences."
Disclaimer
This article is for informational purposes only and is not meant to offer medical advice.
Nicoletta Lanese is the health channel editor at Live Science and was previously a news editor and staff writer at the site. She is a recipient of the 2026 AHCJ International Health Study Fellowship, with a project focused on antibiotic stewardship practices in Japan and the U.S. They hold a graduate certificate in science communication from UC Santa Cruz and degrees in neuroscience and dance from the University of Florida. Beyond Live Science, Lanese's work has appeared in The Scientist, Science News, the Mercury News, Mongabay and Stanford Medicine Magazine, among other outlets. Based in NYC, she also remains involved in dance and performs in local choreographers' work.
View More
You must confirm your public display name before commenting
Please logout and then login again, you will then be prompted to enter your display name.
