The World Health Organisation is planning for the “worst-case scenario” after the Democratic Republic of Congo (DRC) conformed the first death in a new Ebola outbreak on Thursday.

On Friday nine other countries countries were issued with alerts, with the regional risk from the deadly disease being classed as “moderate”. 

Eleven people are now confirmed to be infected with the highly infectious virus in the DRC, including three medical staff. The World Health Organisation (WHO) hopes to deploy a vaccine in the coming days.

The WHO said at least 17 people have died since inhabitants of a village in north-west DRC began showing symptoms resembling Ebola in December. However, those cases were not confirmed through testing.

This is the ninth time Ebola has been recorded in DRC since the disease made its first known appearance in the 1970s.

In a statement, Congo’s Health Minister, Oly Ilunga, said: “One of the defining features of this epidemic is the fact that three health professionals have been affected. This situation worries us and requires an immediate and energetic response.”

Most of the cases so far have been recorded around the village of Ikoko Impenge, near the north-western town of Bikoro.

“After contact, the nurses began showing signs … We have isolated them,” Serge Ngaleto, the director of Bikoro’s main hospital, told Reuters by phone.

Congo’s experience of Ebola and its remote geography mean outbreaks are often localised and relatively easy to isolate.

But Ikoko Impenge and Bikoro are close to the banks of the Congo River, a major artery for trade and transport upstream from the capital Kinshasa.

A spokesman for the director of epidemiology in DRC said government experts would meet on Thursday to discuss measures to prevent it crossing the border to neighbouring Congo-Brazzaville. 

Nigeria’s immigration service said on Thursday it had increased screening tests at airports and other entry points as a precautionary measure. Similar measures helped it contain the virus during the West African epidemic that began in 2013.

Officials in Guinea and Gambia both said they had heightened screening measures along their borders to prevent the spread.

Democratic Republic of Congo’s health ministry said it had dispatched a team of 12 experts to the north-west to try to trace new contacts of the disease, identify the epicentre and all affected villages and provide resources.

Ebola is most feared for the internal and external bleeding it can cause in its victims owing to damage done to blood vessels.