A US expert says events are unfolding in ways reminiscent of Guinea in 2014.
A WHO spokesman said ring vaccination would be the recommended approach "if pertinent."
The likely index patient has died, as has the person who drove him to a healthcare facility.
Epidemiologists and responders are en route to the DRC to assist, and Doctors without Borders is sending an emergency team.
Yesterday Brazil's Ministry of Health lifted the state of emergency caused by the Zika virus, due to the country's dwindling case counts of the mosquito-borne disease.
Health officials in Liberia have reported a second death in Monrovia linked to an unexplained illness cluster in people who attended the funeral of a religious leader in Greenville, located about 4 hours' drive south of the country's capital in Sinoe County, according to local media reports.
Analysis of 3 urine specimens finds no common pattern.
A WHO official said the hospital cluster involves 17 illnesses, 9 of them fatal, and specimens from 6 people who died tested negative for Ebola.
Saudi Arabia's Ministry of Health (MOH) today announced a new MERS-CoV case, involving a 55-year-old expat man from Wadi Aldwasir who is hospitalized in critical condition. It's not clear if his illness is part of a recent hospital cluster reported from Wadi Aldwasir; he is not a healthcare worker and his infection source is listed as primary, meaning he didn't likely contract the virus from another person.
About 4% of patients traveled, a potential target for curbing disease spread.
