A US doctor infected with Ebola has insisted the only available dose of an experimental serum go to a fellow American patient in Liberia, as one of the countries worst hit by the disease declared a state of emergency.
Dr Kent Brantly and missionary Nancy Writebol are both in a "stable but grave condition", according to an aid organisation, although his condition deteriorated slightly overnight.
The North Carolina-based Samaritan's Purse charity said in a statement "Yesterday, an experimental serum arrived in the country, but there was only enough for one person. Dr Brantly asked that it be given to Nancy Writebol"
The charity also said Dr Brantly (33) had been given a unit of blood from a boy (14) who survived Ebola because of the American's medical care.
It is hoped the boy may have developed antibodies that could help Dr Brantly fight off the infection, which has no vaccine or specific treatment.
The Ebola outbreak is the worst in history - and has killed 729 people in West Africa, according to the World Health Organisation (WHO), which announced a US$100m (€74.4m) plan to tackle the disease.
In Sierra Leone, which accounts for around a third of all deaths from the disease, President Ernest Bai Koroma declared a state of emergency, saying ebola "poses as an extraordinary challenge".
Nancy Writebol, with her husband David | Image: Samaritan's Purse
Need to take response "to a new level"
Officials at Emory University Hospital in Atlanta, Georgia, said they expected one of the ill Americans to be transferred to its facility in the coming days, though they declined to say which one.
Dr Brantly's wife and two children returned to their home in Texas before he displayed symptoms of the disease in the Liberian capital Monrovia.
The husband and fellow missionary of Ms Writebol is only allowed to visit her through a window, or while wearing a protective suit.
US health authorities on Thursday recommended against non-essential travel to Guinea, Liberia and Sierra Leone, the three African nations worst affected by the outbreak.
WHO Director-General Margaret Chan plans to meet the presidents of the affected nations on Friday in Conakry, Guinea. She said they need to take the response "to a new level".
On Thursday, Sierra Leone declared a state of emergency and called in troops to quarantine ebola victims, a day after Liberia also introduced sweeping measures.
The Sierra Leone football squad has been barred from travelling to the Seychelles for an African Cup of Nations qualifier because of fears over the virus.
So far, one US citizen has died from Ebola, in Nigeria, after he took a flight from Liberia. That case is prompting the International Civil Aviation Organization to consider introducing passenger screenings for the disease.
Two other American volunteers remain in isolation in West Africa after coming into contact with an ebola sufferer, who later died. The pair - working for America's Peace Corps movement - have not displayed symptoms but are under observation.
The Peace Corps said on Wednesday it was evacuating 340 volunteers from Liberia, Guinea and Sierra Leone.