Ugandan authorities have begun a clinical trial of a vaccine against the Sudan strain of Ebola that has killed one person in the outbreak declared last week.

Test results on the sick people are pending, and a top WHO official said the outbreak response is proceeding rapidly.

Uganda has begun a trial vaccination programme for the strain of Ebola viral infection that is behind Sudan's latest outbreak, according to the World Health Organization (WHO), while the number of confirmed cases has risen to three.