GENEVA — The Ebola outbreak unfolding in the Democratic Republic of Congo (DRC) and Uganda poses a “low” risk globally, according to an expert committee of the World Health Organization (WHO).

However, the national and regional risk is “high”, according to the International Health Regulations (IHR) Emergency Committee.

Last Sunday, WHO Director-General Dr Tedros Adhanom Ghebreyesus had already declared the outbreak a public health emergency of international concern (PHEIC), the WHO’s second-highest level of alert, before convening the emergency committee. This is the first time in WHO’s history that this has occurred.

Tedros was motivated by the scale and speed of the spread of the Bundibugyo virus, a rare and particularly deadly strain of Ebola, which has killed at least 131 people and infected over 500 others.

The emergency meeting, convened on Tuesday to assess the threat of the current outbreak, concurred that the situation is a PHEIC but “not a pandemic emergency,” Tedros told a media briefing on Wednesday.

The committee, chaired by Professor Lucille Blumberg, agreed with the Director-General’s assessment and is finalising its recommendations in the coming days.

“Our prime aim was to support the decision and decide whether this is a public health emergency of international concern, and to consider whether there’s a pandemic emergency. The former was agreed to,” Blumberg said.

Investigations into the outbreak’s origin

“Investigations are ongoing to ascertain when and where exactly this outbreak started,” said Anaïs Legand, a technical officer for high-threat pathogens at WHO’s health emergencies programme.

“Given the scale, we are thinking that it has started probably a couple of months ago, but investigations are ongoing, and our priority is really to cut the transmission chain by implementing contact tracing, isolating and caring for all suspect and confirmed cases.”

The Bundibugyo species was last seen in 2007, and there is currently no vaccine or treatment licensed for it. Investigators say the true scale of the epidemic in DRC is much larger than current case counts suggest.

War, and a very long drive

WHO officials laid out several reasons the outbreak escaped detection.

The province of Ituri, where it emerged, is engulfed in war. Fighting between the DRC army and the M23 armed group has intensified in recent months, displacing more than 100,000 people.

Beyond the conflict, eastern DRC is among the most challenging places in the world to mount a public health response. Health facilities are sparse, roads are limited, and much of the terrain is forested and mountainous. A previous Ebola outbreak in the same region in 2018-19 took close to two years to bring under control, even with a licensed vaccine available.

Dr Mohamed Yakub Janabi, WHO’s regional director for Africa, said the combination of factors made early detection enormously difficult.

“Detecting outbreaks such as Ebola in a complex setting like Ituri province in the DRC is inherently challenging,” he said. “Surveillance systems rely on a combination of community reporting, local health facilities, lab confirmation, and partner coordination.”

Samples from the outbreak zone must travel 1,700 kilometres to reach the Institut National de Recherche Biomédicale in Kinshasa, the only facility in the country with the capacity to test for Bundibugyo. 

The distance to the capital is comparable to London to Warsaw – a roughly a 24-hour drive on smooth European roads, a far cry from the remote jungle tracks and dirt roads of Ituri.

“In remote or insecure areas, it can take time for cases to be recognised and samples transported,” Janabi said.

Symptoms mistaken for endemic diseases

The Bundibugyo strain’s early symptoms also overlap with diseases endemic to eastern DRC, leading health workers to mistake initial cases for more common illnesses.

“Nonspecific early symptoms, for instance, if you take malaria and typhoid, the early symptoms are the same,” Tedros said. “The region is very endemic to those diseases, so the health workers will associate the early signs with malaria or typhoid, and they can’t diagnose based on the symptoms. They may start treating that.”

Dr Abdi Mahamud, WHO’s director for health emergency alert and response operations, said the diagnostic challenge would have tripped up better-resourced systems.

“This outbreak is happening in a highly endemic [setting for] other diseases that present similar symptoms – malaria, dysentery, and others,” he said. “If you don’t have that high index of suspicion, if you don’t have the right facility to test, even in high-income countries, you will have that delay in the start of an outbreak.”

Diagnostic tests routinely used across the region added another layer of delay. The Bundibugyo strain belongs to a different genus, Orthoebolavirus, than the more common Zaire strain that most existing tests are optimised to detect.

“There was a problem linked to the traditional test we use,” Tedros said. “The traditional test is optimised with Zaire, and the same sample was taken and tested, but since the test kit is optimised with Zaire, [Bundibugyo] could not be detected.”

No vaccine, but a pipeline

The Bundibugyo strain has no licensed vaccine or therapeutic. WHO’s research and development lead, Vasee Moorthy, said a pipeline of candidates is being accelerated but remains months away.

Moorthy said the most promising candidate is an rVSV Bundibugyo vaccine, the equivalent for this strain of Ervebo, the licensed Merck vaccine used against the more common Zaire Ebola strain since 2019.

“There are no doses of this which are currently available for clinical trial, so this needs to be prioritised,” Moorthy said. “The information that we have is that this is likely to take six to nine months.”

A second candidate, built on the ChAdOx1 platform used in the AstraZeneca COVID-19 vaccine, is being developed by Oxford and the Serum Institute of India.

“They are manufacturing that as we speak, but there is no animal data to support [its efficacy],” Moorthy said. “It is possible that doses of that could be available for clinical trial in two to three months, but there is a lot of uncertainty about that.”

Even in the most optimistic scenario, neither candidate is likely to be available to materially shape the trajectory of the current outbreak.

In the meantime, the response is being built around the basics: safe treatment centres, patient referral pathways, contact tracing, and the protection of health workers, among whom the first confirmed case in the outbreak was identified.

“The protection of healthcare workers and families is absolutely paramount,” Blumberg said. “The people in the area and those who respond need to be kept safe and allowed to be able to do what they need to do in a critical time such as this.”

Tedros: Rubio suffers ‘lack of understanding’

The WHO chief used the press conference to push back at US Secretary of State Marco Rubio, who said this week the agency had been “a little late to identify this thing.”

The US has banned citizens of the DRC, Uganda and Sudan from entry, closed its only dedicated Ebola lab, withdrawn from the WHO, and defunded the agency.

“On what the Secretary said, it could be from a lack of understanding of how IHR works, and the responsibilities of WHO and other entities,” Tedros said. “We don’t replace the country’s work, we only support them, so that’s why there could be some lack of understanding.”

Tedros suggested conflict in the affected region was a more fundamental factor in the delay than anything WHO could have done differently.

“Health facilities cannot work optimally when there is conflict and when the health workers are also fleeing as part of the community which is displaced,” he said. “It affects the whole surveillance system, and not only that, but it also affects access.” 

“I think that’s what we should understand, the secretary or others.” 

Asked repeatedly whether US funding cuts to DRC surveillance programmes had contributed to the outbreak going undetected, Tedros declined to draw a direct line. 

“We don’t need to jump to conclusions before we understand the whole complexity. It would be very difficult to associate it with funding alone,” he said, noting that the diagnostic gap was a question of the wrong tests being administered rather than supply.

Legand echoed the point, noting the issue stems from test type, not supply: “For the time being, it’s not a supply issue. We need to ensure that the right platform with the right data arrives at the right place. This is the work that is being done as we speak.”

The outbreak, meanwhile, continues to spread through a war zone with no vaccine, no cure, and a diagnostic system still catching up to the strain it now faces.

Image Credits: @WHO African Region, Gage Skidmore.