A second American missionary stricken with Ebola is expected to fly to a US isolation unit for treatment tomorrow.
Plans for Nancy Writebol to leave Liberia with a medical evacuation team follow the arrival of a colleague at Emory University Hospital's infectious disease unit in Atlanta, Georgia.
Mrs Writebol is in good spirits despite her diagnosis, said the pastor of Munro's Calvary Church in her home town of Charlotte, North Carolina.
"She is holding her own," the Rev John Munro said. The non-denominational evangelical congregation sponsors the nurse and her husband David as missionaries in Liberia, one of the West African nations grappling with the worst outbreak of Ebola recorded there.
Mrs Writebol's mission team partner, Dr Kent Brantly, is improving after being admitted to Emory's quarantine unit on Saturday, his wife Amber said.
"Our family is rejoicing over Kent's safe arrival and we are confident that he is receiving the very best care," Mrs Brantly said, adding that she was able to see her husband yesterday.
Dr Brantly and Mrs Writebol served on the same mission team treating Ebola victims when they contracted the virus themselves. Dr Brantly was a physician in the hospital compound near Monrovia when he became infected.
Mrs Writebol worked as a hygienist whose role included decontaminating those entering or leaving the Ebola treatment area at the hospital.
There is no cure for Ebola, which causes haemorrhagic fever that kills at least 60% of the people it infects in Africa. Ebola spreads through close contact with bodily fluids and blood, meaning it is not spread as easily as airborne influenza or the common cold.
Africa's under-developed health care system and inadequate infection controls make it easier for the Ebola virus to spread and harder to treat.
But any modern hospital using standard infection-control measures should be able to handle it, according to medical experts, and Emory's infectious disease unit is one of about four in the US that is specially equipped to test and treat people exposed to the most dangerous viruses.
Patients are quarantined, sealed off from anyone who is not in protective gear. Lab tests are conducted inside the unit, ensuring that viruses do not leave the quarantined area. Family members can see and communicate with patients only through barriers.
Dr Brantly arrived under stringent protocols, flying from West Africa to Dobbins Air Reserve base outside Atlanta in a small plane equipped to contain infectious diseases. A police escort followed his ambulance to Emory, where he emerged, dressed head to toe in white protective clothing, and walked into the hospital without help.
The Texas medic is a Samaritan's Purse missionary. The Writebols are working through SIM USA. The two Christian organisations have partnered to provide health care in West Africa.
Mr Munro said the Writebols were "quiet, unassuming people" who "felt called by God" to mission work overseas. They first went to Africa in the late 1990s, he said, working at a home for widows and orphans in Zambia.
"They take the Great Commission literally," Mr Munro said, referring to the scriptural instruction from Jesus to "make disciples of all nations".
He recalled speaking to the couple when the Ebola outbreak began. "We weren't telling them to come back; we were just willing to help them come back," he said. "They said, 'The work isn't finished, and it must continue'."
Mr Writebol spoke to his home church congregation last week through an internet audio connection, Mr Munro said. Mrs Writebol "couldn't join the call because of her condition", but the pastor said Mr Writebol told them his wife was able to walk a little on her own.
The outbreak comes as nearly 50 African heads of state come to Washington DC for the US-Africa Leaders Summit - billed as a tool for African nations to integrate more into the world economy and community.
With the outbreak, however, the presidents of Liberia and Sierra Leone have scrapped their plans to attend the three-day summit opening today.
Meanwhile, some airlines that serve West Africa have suspended flights, while international groups, including the Peace Corps, have evacuated some or all of their representatives in the region.
In the United States, health chiefs continue to emphasise that treating Dr Brantly and Mrs Writebol in the US poses no risks to the public.
"The plain truth is that we can stop Ebola," Dr Tom Frieden, director of the US Centres for Disease Control and Prevention, said on ABC's This Week.
"We know how to control it: hospital infection control and stopping it at the source in Africa."
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