Dar es Salaam, Feb. 4 -- KAMPALA, UGANDA: Ugandan authorities on Monday began a clinical trial of a vaccine against the Sudan strain of Ebola that has killed one person in the outbreak declared last week.

Health workers and others exposed to the Ebola strain are being targeted in the study, which began four days after Uganda announced the death of a nurse in the capital, Kampala. Two more cases were confirmed on Monday in relatives of the first victim.

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Officials are investigating the source of the outbreak. Ebola is spread by contact with bodily fluids of an infected person or contaminated materials. Symptoms include fever, vomiting, diarrhea, muscle pain ...