The World Health Organization (WHO) has declared the Ebola crisis in the Democratic Republic of Congo (DRC) a “public health emergency of international concern”.
But it stressed borders should not be closed, adding that the risk of the disease spreading outside the region was not high.
The outbreak in the DRC has killed more than 1,600 people.
This week, the first case was detected in Goma, home to more than a million.
“It is time for the world to take notice,” WHO chief Tedros Adhanom Ghebreyesus told a news conference in Geneva.
He said he had accepted the advice of his advisory board to invoke the emergency provision PHEIC, which has only been used by the United Nations health agency four times previously. This includes the Ebola epidemic that