While the risk of the latest outbreak spreading into other countries is low, nine nearby countries have been put on high alert, Salama said. Cases near a major city are a concern, as is the outbreak's location. "This is a highly complex sophisticated operation in one of the most hard terrains on Earth", Salama said.
"We still dispose of the well-trained human resources that were able to rapidly control previous epidemics".
The viral disease, which has no known cure although a vaccine has been successfully trialled, was first reported in 1976 in the Congo.
More than 11,000 people died and some 28,000 cases were reported in an Ebola outbreak in West Africa between 2014 and 2015.
After meeting with DR Congo President Joseph Kabila in Kinshasa, the WHO chief praised "the government's very strong leadership" in responding to the health crisis and its "good coordination" with partners such as Unicef and Doctors without Borders (MSF).
Bikoro's airstrip can not yet accommodate even small aircraft, so the initial response will rely on United Nations helicopters.
The WHO was criticised for bungling its response to that epidemic, and so has moved quickly. "We need to be prepared for all scenarios", he added.
Plus healthcare workers have been infected, and Salama said infected healthcare workers can spread the virus to people they are caring for. "If you have 18 of  cases that are fatal, that tells me we don't know how big the iceberg is - that there's more that have not been detected yet", said Daniel Bausch, the director of the UK Public Health Rapid Support Team, who has been advising on the outbreak response.
Before the weekend, only five samples had been taken and sent to Kinshasa, two of which tested positive for Ebola. The declaration came after laboratory results confirmed two cases of the disease in the province of Bikoro in the northwestern part of the country. According to STAT, the cold-chain equipment to keep the vaccine chilled was to arrive in DRC yesterday and the vaccine itself will be shipped from Geneva later this week. "Further in order to mitigate the threat, the ministry has established the National Health Emergencies Council whose role is to act prevent importation of Ebola or any other diseases into Kenya", the CS said.
The Ebola virus is highly contagious and causes a range of symptoms including fever, vomiting, diarrhea, generalized pain or malaise and in many cases internal and external bleeding.