Health and Medicine
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The growing Ebola outbreak that recently passed the ominous milestone of 1,000 confirmed cases has a high chance of spreading to a new country.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.According to modeling from the World Health Organization (WHO), there’s a 70 percent chance the Bundibugyo virus will spread to South Sudan, as authorities in the outbreak epicenter in the Democratic Republic of the Congo (DRC) continue to work hard to bring the situation under control.
Up to now, the majority of cases of the disease have been in the DRC, but neighboring Uganda has also seen 20 confirmed cases as of June 22.
We’ve also now recorded the first case outside of Africa for this outbreak. A doctor from France who was returning home after offering humanitarian aid in the DRC is being cared for in a specialized facility and contact tracing is underway.
“Following confirmation of the first imported case of Ebola disease in Europe since the current outbreak began after a doctor returning to France from the Democratic Republic of the Congo tested positive, the European Centre for Disease Prevention and Control (ECDC) calls on EU Member States to continue strengthening their preparedness,” said an official ECDC statement.
A different virus, a different challenge
The DRC has been affected by numerous Ebola outbreaks in the past, but there are some factors that set the current situation apart.
The virus in question is the rarer Bundibugyo ebolavirus. Previous large outbreaks have largely been driven by Orthoebolavirus zairense, a related virus that’s usually just called the Ebola virus (you may also hear people calling it the “Zaire strain” or “Zaire virus”).
O. zairense was first identified as the causative agent of severe hemorrhagic fever in 1976 and became infamous for causing outbreaks with case fatality rates of up to 90 percent, making it one of the deadliest viruses known to humanity.
As a result, efforts were made to develop specific treatments and vaccines for this disease – efforts many have criticized as not going far enough, fast enough. Still, today we do have two licensed Ebola vaccines, one of which is held in a global stockpile and recommended for use in outbreak situations.
The problem is, it’s specific to O. zairense. The scientific community is mobilizing to develop a vaccine for Bundibugyo; but, as things stand, vaccines are not an option health workers can currently use to combat this outbreak.
There was also a substantial delay between the first cases emerging and official confirmation of the outbreak – six weeks, according to the latest estimates.
The outbreak arose in the DRC’s Ituri Province, a region that’s been beset with brutal conflict in recent years. There’s limited healthcare infrastructure and the unrest has led to a huge number of people becoming displaced, meaning they lose access to health facilities altogether or are unable to attend them due to security concerns.
In 2025, the International Committee of the Red Cross described civilians in the region being trapped in a “murderous cycle” and explained how it has been providing tens of thousands of people with household items, tools, and plant cuttings as they try to rebuild their lives after displacement.
Against this backdrop, an outbreak of Ebola has the potential to be devastating, and we are unfortunately seeing that play out. As of June 22, there have been 1,048 lab-confirmed cases of Ebola in the DRC and 267 deaths.
With a small number of cases also reported in Uganda, authorities in neighboring countries are on high alert. But what are the chances of the virus spreading farther afield?
South Sudan requires “urgent reinforcement”
A new modeling study from experts at the WHO Regional Office for Africa has projected how the outbreak could continue to play out.
The team simulated low, central, and high transmissibility scenarios, with the central scenario being most likely. It projects that confirmed cases could reach 8,210 by September 2026 if the current rate of transmission is sustained.
The worst-case scenario – which the authors stress is not likely – produced a high of 66,000 cases by September. This would be if all control measures ceased, which goes to show how vital the response of health authorities is in averting disaster.
So far, the outbreak has most closely followed the trajectory laid out in the central scenario.
Uganda saw some early cases brought into the country by travelers from the DRC, but was able to respond quickly due to prior experience dealing with Ebola outbreaks.
Now, the modelers say, attention should turn to South Sudan. They estimate that there’s a nearly 70 percent chance of at least one case being detected there.
“Cross-border movement between eastern DR Congo, Uganda, and South Sudan occurs through both formal and informal routes, with many individuals crossing borders daily for trade, health care, and family visits,” they write. “Such mobility substantially increases the likelihood of regional spillovers.”
They describe South Sudan’s health system as “weaker” than Uganda’s, with factors like gaps in contact tracing, limited border surveillance, and less adherence to safe burial practices all being raised.
Safety around burials and funerals is particularly key to the management of Ebola as handling corpses is known to be a major route of transmission, with infection risk increasing around the time of death and remaining high even after a patient has died.
The models are not intended to be predictions, the authors stress – there’s no guarantee the situation will play out just as the computer suggests, and they will be updated with more data as it becomes available.
Nonetheless, they call for leaders in South Sudan to “continue to reinforce infection prevention and control, rapid response capacity, and cross-border surveillance under International Health Regulations 2005.”
The study is published in The Lancet Infectious Diseases.
