Three health care workers were also among 19 deaths, the WHO said in a statement.
As of Friday, 34 Ebola cases have been reported in the area in the past five weeks, including two confirmed, 18 probable (deceased) and 14 suspected cases.
"This will be tough and it will be costly". It can be transmitted by close contact with infected animals or people, usually through blood or other bodily fluids.
A cordon ribbon is seen around the isolation ward at Bikoro hospital in the Democratic Republic of Congo.
The worst-ever Ebola outbreak started in December 2013 in southern Guinea before spreading to two neighbouring west African countries, Liberia and Sierra Leone, killing more than 11 300 people out of almost 29,000 registered cases.
EVD, formerly known as Ebola hemorrhagic fever, is a severe, often fatal illness in humans.
Director-General Dr Tedros Adhanom Ghebreyesus, who is scheduled to travel to DRC soon, will be taking stock of the situation.
WHO's Africa director, Matshidiso Moeti, told Reuters on Sunday: "We're working on the deployment of these materials, especially readying the cold chain". But he said any country facing such a threat may require worldwide assistance.
There have been 24 recorded outbreaks in west and central Africa, including in DRC, Uganda, Sudan and Gabon, the BBC report added. Its early flu-like symptoms are not always easy to detect.
When an outbreak is detected, World Health Organization responds by supporting surveillance, community engagement, case management, laboratory services, contact tracing, infection control, logistical support and training and assistance with safe burial practices.