The authorities in Mali have confirmed the death of the country’s first Ebola patient, a two-year-old girl.
The World Health Organisation said the toddler had travelled hundreds of kilometres by bus from Guinea through Mali showing symptoms of the disease.
More than 40 people known to have come into contact with her have been quarantined.
The girl was being treated in the western town of Kayes, after arriving at a hospital on Wednesday.
The child had travelled more than 1,000 km (600 miles) from Guinea through the capital, Bamako, to Kayes.
“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,” the WHO said.
The girl’s mother died in Guinea a few weeks ago and the child was then brought by relatives to Mali.
Guinea, Liberia and Sierra Leone have seen most of the 4,800 Ebola deaths.
In the US, the governors of the states of New York and New Jersey have ordered a mandatory 21-day quarantine period for all doctors and other travellers who have had contact with Ebola victims in West Africa.
Anyone arriving from affected West African countries without having had confirmed contact with Ebola victims will be subject to monitoring by public health officials.
The moves go beyond anything so far announced at a national level by the Obama administration and come after a doctor, Craig Spencer, was diagnosed with Ebola following his return to New York from Guinea.
Mali has now become the sixth West African country to be affected by the outbreak, although Senegal and Nigeria have since been declared virus-free by the WHO.
The WHO has three experts in Mali evaluating its ability to cope with Ebola and will send at least four more over the next few days, spokeswoman Fadela Chaib said.
With porous borders, countries neighbouring Guinea, Sierra Leone and Liberia are on high alert for possible imported cases of the virus, says BBC Africa health correspondent Anne Soy.Vaccine boost
The World Health Organization (WHO) has meanwhile announced that hundreds of thousands of vaccine doses should be available in the first half of 2015.
WHO Assistant Director Dr Marie-Paule Kieny told a news conference in Geneva that five more vaccines would be in the clinical trial stage in January. Two are already being tested on humans.
“The pharmaceutical companies developing these vaccines, as well as the ones which are a little bit further along the development path, are committing to ramping up the production capacity to millions of doses to be available in 2015 with hundreds of thousands ready in the first half of next year,” she said.
Vaccine trials in the worst-affected countries could begin in December, Dr Kieny said.
In the US, two nurses infected with Ebola while caring for dying Dallas patient Thomas Duncan have been declared free of the virus.
One of them, Nina Pham, 26, had a meeting with President Barack Obama at the White House, hours after being discharged.
“I feel fortunate and blessed to be standing here today,” she said. “I am on my way back to recovery.”
The other nurse, Amber Vinson, has also been declared virus-free, but she will remain in treatment in Atlanta until further notice.
Thomas Duncan died earlier this month and it is still unclear how the nurses contracted the virus while wearing protective clothing.
The news of the two nurses’ recoveries comes a day after a new US infection, the first in New York.
Craig Spencer, 33, began to feel tired on Tuesday and developed a fever and diarrhoea on Thursday. He had recently returned from Guinea where he had been working for medical charity, Medecins Sans Frontieres.
Dr Spencer is being kept in isolation at New York’s Bellevue Hospital.