France, May 18 -- The outbreak, caused by the Bundibugyo strain of Ebola, has already spread into neighbouring Uganda and prompted the World Health Organization to declare a "public health emergency of international concern" on Sunday.

Health officials say there is no approved vaccine or specific treatment for the strain, while aid agencies warn that conflict, displacement and weak infrastructure are making it harder to trace contacts and isolate cases.

The Africa Centres for Disease Control and Prevention reported 336 suspected cases and 88 deaths over the weekend, although only a small number of cases have so far been confirmed through laboratory testing. 'Uncertainties'

The WHO has warned there are still "significant uncertainties" ...