A British military healthcare worker was being treated for Ebola in hospital tonight after being flown back to the UK from Sierra Leone.
Two of her colleagues who were transported back in the RAF plane are also at the Royal Free Hospital (RFH) in Hampstead, north west London, where they will be monitored for the disease as a precaution.
Their arrival back in the UK comes as the World Heath Organisation (WHO) said the death toll from the Ebola epidemic has surpassed 10,000.
Two other military workers are due to arrive back in the UK tomorrow.
Health officials said rapid tracing was undertaken in Sierra Leone to identify anyone who had been in recent close contact with the worker as soon as she was known to be infected.
A total of four military healthcare workers were identified and the two that remain in Sierra Leone will be brought back to the UK tomorrow on separate EU Medevac flights to Newcastle.
They will then be taken to the city's Royal Victoria Infirmary for monitoring in line with Ebola response plans.
Public Health England (PHE) announced yesterday that the female worker had tested positive after being exposed to the virus while treating patients in Sierra Leone.
Up to 700 British military personnel are currently deployed in the West African country to aid the Ebola effort.
Nurses Pauline Cafferkey and Will Pooley - the only other Britons to have tested positive for the disease - were also treated at the RFH and both made full recoveries.
Dr Ben Neuman, virologist at the University of Reading, said the UK's highly-skilled medical teams and state-of-the-art equipment and technology offer the infected worker the best chance of recovery.
He said a new batch of ZMapp, which was used to treat Mr Pooley, is not available so Japanese antiviral drug Favipiravir, which he said has shown some "early promising results" in west African Ebola clinics, might be used.
"She may also be given antibody-rich serum from Ebola survivors to knock down the amount of virus in her blood while her immune system is learning to fight Ebola," he said.
"The Royal Free Hospital has a 100% record in treating Ebola cases so far. Let's hope that doesn't change."
Professor Andrew Easton, virologist at the University of Warwick, said the infected worker will be kept in a high-level isolation unit where she will be subjected to assessments before she can be treated.
"The first phase will be to assess the patient to determine what level of the disease they are experiencing," he said.
"That information will determine how things will progress.
"At the moment the only conventional treatment is supportive to improve their physical state and ability to fight the infection."
He said drugs such as ZMapp have not been used on many people yet, but even though they have not been clinically trialled they were worth trying out under such exceptional circumstances.
"They can fast-track treatment in situations like this, much like they did with HIV drugs," he said.
"Although they are untested, if they do end up having a positive effect it makes them worth it."
The Ebola outbreak has been raging for more than a year, with Sierra Leone, Guinea and Liberia the worst-affected countries.
But the epidemic has shown signs of slowing down in recent months and Liberia released its last Ebola patient from a treatment centre last week.
Mr Pooley, from Eyke in Suffolk, tested positive for the virus last August and was flown back to the UK by the RAF.
He has since returned to Sierra Leone to resume his work.
Mrs Cafferkey, from Cambuslang in South Lanarkshire, had volunteered with Save The Children at a treatment centre in Kerry Town and was not diagnosed with Ebola until after she returned to the UK in December.
She was discharged from the RFH in January.