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.

Confirmation of Ebola Sudan in Uganda poses a high risk of further spread owing to the index patient's movements across multiple districts and healthcare facilities, the WHO said. It added that rapid containment is critical, because of Kampala's dense population and Mbale's location near the border with Kenya.

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.