Sri Lanka, May 21 -- The World Health Organization (WHO) says it could take up to nine months before a vaccine against this particular species of Ebola is ready.

Two possible "candidate vaccines" against the Bundibugyo species are being developed, but neither had gone through clinical trials yet, WHO advisor Dr Vasee Moorthy said on Wednesday.

WHO chief Dr Tedros Adhanom Ghebreyesus said there have been 600 suspected cases of Ebola and 139 suspected deaths but numbers are expected to rise given the time taken to detect the virus.

Speaking to journalists in Geneva, he said 51 cases have been confirmed in the Democratic Republic of Congo - where the first case was reported - and two in neighbouring Uganda.

On Sunday, the WHO declared a ...