The World Health Organization on Tuesday voiced concern about the "scale and speed" of an Ebola outbreak that has killed an estimated 131 people in the Democratic Republic of Congo and warned it could be lengthy.

The UN health agency has declared the surge of the highly contagious haemorrhagic fever an international health emergency and called an urgent meeting on the crisis.

No vaccine or therapeutic treatment exists for the Bundibugyo strain of Ebola which is responsible for the outbreak declared in the east late last week.

Ebola has killed more than 15,000 people in Africa in the past half-century.

WHO chief says he is 'deeply concerned'

"We have recorded roughly 131 deaths in total and we have around 513 suspected cases," Congolese Health Minister Samuel Roger Kamba said on national television early on Tuesday.

"The deaths we are reporting are all the deaths we have identified in the community, without necessarily saying that they are all linked to Ebola," he added.

WHO chief Tedros Adhanom Ghebreyesus said he was "deeply concerned about the scale and speed of the epidemic."

Speaking from the DRC, Anne Ancia, the WHO's representative, told reporters in Geneva that a vaccine candidate called Ervebo was among those being looked at but it was likely to take at least "two months for it to be available."

Outbreak will not be over in two months' time

It could still be useful, she added, since "I don't think that in two months we will be done with this outbreak."

The DRC's deadliest Ebola outbreak, between 2018 and 2020, claimed nearly 2,300 lives from 3,500 cases.

The epicentre of the new cases is in northeastern Ituri province on the border with Uganda.

The virus has already spread into neighbouring provinces, as well as beyond the DRC's borders into Uganda.

'Mystical illness'

"Unfortunately, the alert was slow to circulate within the community, because people thought it was a mystical illness, and so, as a result, the sick were not taken to the hospital," Kamba said.

The Ebola outbreak is the 17th in the vast Central African country of more than 100 million people.

Vaccines are only available for the Zaire strain of the disease, which has caused the biggest recorded outbreaks.

The Bundibugyo strain has previously been responsible for outbreaks in Uganda in 2007 and in the DRC in 2012. The mortality rate was 30 to 50%.

DRC president urges calm

Congolese President Felix Tshisekedi on Tuesday urged citizens to keep "calm" and take precautions, the presidency said on X, adding he had asked the government to step up the response to the outbreak.

Suspected cases have been reported in the commercial hub of Butembo in neighbouring North Kivu province, some 200 kilometres from the epidemic's ground zero, Kamba said, without giving further details.

Another case has been recorded in Goma, the North Kivu provincial capital, which was seized by M23 rebels in January 2025.

Congolese doctor Denis Mukwege, who won the Nobel Peace Prize in 2018, appealed to M23 rebel group to reopen the city's airport to help combat the outbreak.

Humanitarian access

Goma airport has been closed since the M23 captured the city.

The front line dividing the anti-governmental group and government forces runs through the provinces of North Kivu and neighbouring South Kivu.

"Humanitarian access and coordination between the various stakeholders, particularly the parties to the conflict, could be one of the challenges for the response," Francois Moreillon, of the International Committee of the Red Cross in the DRC, told AFP on Monday.

He urged guarantees for effective access, cooperation and humanitarian coordination.

Uganda confirms two cases

The Africa Centres for Disease Control and Prevention (Africa CDC) has declared the outbreak a continental public health emergency.

The International Federation of Red Cross and Red Crescent Societies also said it had activated its highest level of emergency response.

Tedros said that 30 cases had been confirmed to be Ebola in Ituri province.

"Uganda has also informed WHO of two confirmed cases in the capital of Kampala, including one death among two individuals who travelled from DRC," he said.

US announces restrictions

The United States announced it was screening air passengers from outbreak-hit areas and temporarily suspending visa services.

It also urged citizens to avoid travel to the DRC, South Sudan and Uganda, and to reconsider travel to Rwanda.