The Ebola virus spreading in Congo is a rare species with no vaccines or treatments

The Ebola outbreak in the Democratic Republic of Congo has killed nearly 120 people, and the virus responsible is a rare species that has no approved vaccines or treatments — a fact that has public health experts particularly concerned about the path to containment.

The outbreak, now in its 17th occurrence of Ebola in the DRC, is caused by the Bundibugyo virus — a species of Ebola that has only been documented twice before, both times in the same region of the Congo River basin.

"There's nothing even close to ready for clinical trials," said Dr. Celine Gounder, an infectious disease specialist and epidemiologist who treated patients during the 2014-2016 West Africa Ebola epidemic. "That means responders, healthcare workers, and other aid workers are really back to the basics."

## What Makes Bundibugyo Different

The Ebola virus family includes six known species, of which four can cause disease in humans. The most well-known is Zaire ebolavirus, which was responsible for the devastating 2014-2016 West Africa outbreak that killed over 11,000 people. Vaccines and treatments developed since then — including the rVSV-ZEBOV vaccine and monoclonal antibody treatments like Inmazeb and Ebanga — target the Zaire species specifically.

Bundibugyo virus is a different species. Those vaccines and treatments don't work against it.

Dr. Tom Ksiazek, a virologist at the University of Texas Medical Branch who directed the CDC's Special Pathogens Branch when it first identified Bundibugyo virus in 2007, explained that the virus has caused only two previous outbreaks, both in the Congo River basin. The first, in 2007 in the Bundibugyo District of Uganda, sickened over 200 people and had a case fatality rate around 25-30%. The second, in 2012 in the DRC, was smaller.

From the limited data available, Bundibugyo appears slightly less lethal than Zaire ebolavirus — but "a 30%-plus mortality rate is still quite scary," Gounder noted.

## How It Spreads — And How It Doesn't

Bundibugyo virus spreads the same way as other Ebola species: through close contact with bodily fluids — sweat, blood, feces, or vomit — of sick or deceased patients. Healthcare workers and family members caring for sick individuals face the highest risk.

"Very often we see doctors and nurses among the first to be infected and to die," said Gounder, who is editor-at-large for public health at KFF Health News.

Unlike some viral hemorrhagic fevers, Ebola is not airborne. Casual contact — being in the same room, passing on the street — carries essentially zero risk. The danger comes from direct contact with infected fluids, which is why burial practices that involve washing and preparing the body are a major transmission route.

## The Containment Playbook — Without Vaccines

With no vaccines or drug treatments available, responders are relying on the same tools that stopped every previous Ebola outbreak in the DRC: public education, contact tracing, rapid testing, isolation of confirmed cases, and safe burial practices.

"It's important to keep in mind that every single Ebola outbreak that has occurred in the DRC — we're on our 17th now — has been stopped," said Lina Moses, an epidemiologist and disease ecologist at Tulane University.

That's a reassuring track record, but the current outbreak is larger than most. Nearly 120 deaths is a significant number for Bundibugyo, and the case count continues to rise. The lack of a vaccine means there's no ring-vaccination strategy — the approach that helped contain the 2018-2020 DRC outbreak of Zaire ebolavirus by vaccinating contacts of confirmed cases.

## The U.S. Connection

Eighteen Americans who were potentially exposed on the cruise ship MV Hondius — which had a separate hantavirus outbreak, not Ebola — are currently under observation at facilities in Nebraska and Atlanta. The CDC has confirmed there are no known Ebola cases in the United States.

The risk of Bundibugyo reaching the U.S. is considered extremely low. Ebola requires direct contact with bodily fluids, and the outbreak region in the DRC is remote with limited international travel connections. The U.S. has robust screening protocols for travelers from affected regions, and the experience gained during the 2014-2016 West Africa outbreak has improved hospital preparedness nationwide.

## What This Means For You

**If you're in the DRC or surrounding countries**: The risk is real but manageable. Avoid contact with sick individuals, do not touch bodies of deceased persons, and seek medical attention immediately if you develop fever, muscle aches, or bleeding symptoms after potential exposure.

**If you're in the United States**: There is no risk from this outbreak. The CDC has confirmed zero domestic Ebola cases. The monitoring of returning travelers is a precaution, not a sign of imminent danger.

**For public health policy**: The Bundibugyo outbreak highlights a critical gap in pandemic preparedness. The world has vaccines and treatments for Zaire ebolavirus, developed after the 2014-2016 epidemic killed 11,000 people. But for other Ebola species — which are equally capable of causing large outbreaks — we have nothing. Developing broad-spectrum Ebola countermeasures should be a global health priority, not an afterthought.

**The bottom line**: This outbreak is being fought with 19th-century tools — isolation, tracing, and protective equipment — because the 21st-century tools don't exist for this species of the virus. Every DRC Ebola outbreak has been stopped before. This one can be too. But it will take longer and cost more lives without vaccines.