The Democratic Republic of Congo has announced the first confirmed death in a new outbreak of Ebola virus and said 11 other people were now confirmed to be infected, including three medical staff.
At least 17 people have died since inhabitants of a village in the country's northwest began showing symptoms resembling Ebola in December, according to the World Health Organization.
However, those cases were not confirmed through testing.
This is the ninth time Ebola has been recorded in the Democratic Republic of Congo since the disease made its first known appearance - near the vast central African country's northern Ebola river - in the 1970s.
"One of the defining features of this epidemic is the fact that three health professionals have been affected," Health Minister Oly Ilunga said in a statement.
Most of the cases so far have been recorded around the village of Ikoko Impenge, near the northwestern town of Bikoro.
Congo's long experience of Ebola and its remote geography mean outbreaks are often localised and relatively easy to isolate.
But Ikoko Impenge and Bikoro are situated not far from the banks of the Congo River, a major artery for trade and transport upstream from the capital Kinshasa. The Congo Republic is just on the other side of the river.
A spokesman for the director of epidemiology in Congo Republic said government experts would meet on Thursday to discuss measures to prevent it crossing the border.
Nigeria's immigration service said on Thursday it had increased screening tests at airports and other entry points as a precautionary measure.
Officials in Guinea and Gambia both said they had heightened screening measures along their borders to prevent the spread.
Ebola is most feared for the internal and external bleeding it can cause in its victims owing to damage done to blood vessels.
