The death toll from the Ebola outbreak in the Democratic Republic of Congo has risen to 26 after a person died in the northwest city of Mbandaka, Health Minister Oly Ilunga said on Monday.

“A death was recorded (on Sunday), while two people who had been confirmed as ill with the Ebola virus were cured on Saturday,” he said.

“The two people who were cured have returned to their families,” he told reporters.

Those two cases occurred at Bikoro, a remote rural area where the outbreak was announced on May 8 and then spread to Mbandaka — an event that has deeply worried health experts.

The current toll is 49 cases, comprising 22 confirmed by laboratory tests, 21 probable cases and six suspected cases, Ilunga said. Three new cases had been reported on Saturday.

Authorities in the DRC on Monday were to launch a programme to immunise first responders with an experimental Ebola vaccine.

The first phase will unfold in Mbandaka on Monday, followed on Saturday in Bikoro, about 150 kilometres away.

Donors have promised 300,000 doses of the vaccine, a government spokesman said, of which around 5,400 have already been received.

The World Health Organisation (WHO) has dispatched 35 immunisation experts, including 16 mobilised during the last deadly outbreak in West Africa which occurred in 2013. The rest of the team is made up of newly trained Congolese staff.

“I'm pleased to say that vaccination is starting as we speak,” Tedros Adhanom Ghebreyesus, the WHO's director-general, said on Monday as the UN's health agency met in an assembly.

Alarm bells sounded on Thursday when a first case was reported in Mbandaka, a city of around 1.2 million people located on the Congo River.

A major transport hub, the city is located upstream from the DRC capital Kinshasa and Brazzaville, the capital of the Republic of Congo, and downstream from Bangui, the capital of the Central African Republic, one of the poorest countries in the world.

One of the world's most notorious diseases, Ebola is a virus-caused haemorrhagic fever that in extreme cases causes fatal bleeding from internal organs, the mouth, eyes or ears.

It has a natural reservoir in a species of tropical African fruit bats, from which it is believed to leap to humans who kill and butcher the animals for food.

Transmission among humans then typically spreads through close contact with the blood, body fluids, secretions or organs of someone who is sick with Ebola or has recently died.

The average fatality rate is around 50 per cent, varying from 25pc to 90pc, according to the WHO.

As there is no licensed drug to treat or prevent the disease, doctors use time-honoured methods of identifying and isolating patients, and tracing people who have been in contact with them.

The job, which requires strict safety protocols, is exhausting and requires mustering large numbers of personnel. The task is greatly complicated when the disease spreads to a city.

The outbreak is the ninth in DR Congo since the disease was first identified in 1976. It was named after a Congolese river where the first cases were recorded.

The last outbreak was in 2017, and was rapidly curtailed with four deaths.