Mali's first Ebola victim, a two-year-old girl, has died of the disease amid an alert she travelled across the country by bus while contagious.
The World Health Organisation on Friday said the two-year-old girl was bleeding from her nose during her journey on public transport and may have infected many people.
The girl was travelling from Guinea with her grandmother and passed through several towns in Mali, including two hours in the Malian capital of Bamako before ending their journey in the western city of Kayes.
Her death was confirmed on Friday by health officials speaking to news agencies. Her infection makes Mali the sixth West African country to record a case of the disease.
WHO said 43 people who came into contact with the child, including 10 health workers, were being monitored for symptoms and held in isolation.
"The child's symptomatic state during the bus journey is especially concerning, as it presented multiple opportunities for exposures - including high-risk exposures - involving many people."
WHO also said on Friday that mass trials of an experimental Ebola vaccine could start in West Africa in December and several hundred thousand doses could be available by the first half of next year.
The agency's assistant director general Marie-Paule Kieny said two potential vaccines were undergoing clinical trials. Larger trials in West Africa could begin in December if those tests proved effective.
"All is being put in place to start efficacy tests in the affected countries as early as December," she said at the agency's headquarters in Geneva.
"Before the end of first half of 2015 we could have available a few hundred thousand doses. That could be 200,000 - it could be less or could be more.
More than 4,800 people have died in West Africa of Ebola. Guinea, Liberia and Sierra Leone are the worst affected countries. Nigeria and Senegal were declared Ebola-free last week after no new cases were reported for 42 days.
WHO said on Saturday the number of people believed to be infected by Ebola has risen above 10,000.
The UN health agency said that the number of confirmed, probable and suspected cases has risen to 10,141. Of those, 4,922 people have died.
WHO has said repeatedly that even those very high figures are likely an underestimate as many people in the hardest hit countries have been unable or too frightened to seek medical care.
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