KINSHASA, DR Congo (AFP) — An Ebola outbreak in the Democratic Republic of Congo has killed more than 80 as authorities warned there was no vaccine for the strain in a crisis that the World Health Organization (WHO) declared an international health emergency on Sunday.

A total of 88 deaths and 336 suspected cases of the highly contagious hemorrhagic fever have been reported, the Africa Centers for Disease Control and Prevention (CDC Africa) said in an update on Saturday.

The Geneva-based WHO said early on Sunday the outbreak caused by the Bundibugyo strain of Ebola constituted a "public health emergency of international concern" — the second-highest level of alert under international health regulations.

The global health body warned the true scale of the number of cases and spread was not clear but stopped short of declaring a pandemic emergency, the highest alert level introduced in 2024.

Medical aid group Doctors Without Borders (MSF) said it was preparing a "large-scale response," calling the rapid spread of the outbreak "extremely concerning," in warnings echoed by authorities.

"The Bundibugyo strain has no vaccine, no specific treatment," DR Congo's Health Minister Samuel-Roger Kamba said.

"This strain has a very high lethality rate, which can reach 50 percent."

The strain — which was first identified in 2007 — has also killed a Congolese national in neighboring Uganda, officials said Saturday.

Vaccines are only available for the Zaire strain, which was identified in 1976 and has a higher fatality rate of 60-90 percent.

Health officials had confirmed the latest outbreak Friday in Ituri province in northeastern DRC, bordering Uganda and South Sudan, according to CDC Africa.

"We've been seeing people die for the past two weeks," said Isaac Nyakulinda, a local civil society representative contacted by Agence France-Presse by phone.

"There is nowhere to isolate the sick. They are dying at home and their bodies are being handled by their family members."

According to Kamba, patient zero was a nurse who reported to a health facility in Ituri's provincial capital Bunia on 24 April, with symptoms suggesting Ebola.

Symptoms of the disease include fever, hemorrhaging and vomiting.

"The number of cases and deaths we are seeing in such a short timeframe, combined with the spread across several health zones and now across the border, is extremely concerning," says Trish Newport, MSF Emergency Program manager, which is mobilizing medical and support staff to the area.

Large-scale transport of medical equipment is a challenge in DR Congo, a country of more than 100 million people which is four times the size of France but has poor communications infrastructure.