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Missionary Nancy Writebol, one of two known Americans stricken with Ebola, wasn't looking to abandon her overseas work. But Jeremy Writebol believes his 59-year-old mother can yield a greater good from her impending return to the United States amid West Africa's worst-ever outbreak of the often-deadly virus.

The attention focused on her case "might help develop a cure and resources to help those who are suffering," the younger Writebol said. "I am sure hopeful for that."

A Liberian government official has confirmed that a medical evacuation team is scheduled to fly Nancy Writebol back to the United States early Tuesday. She will receive treatment at Atlanta's Emory University Hospital alongside one of her mission partners, Dr. Kent Brantly, who was admitted Saturday.

The American cases make headlines as dozens of African heads of state converge on Washington for the Monday opening of the U.S.-Africa Leaders Summit, a three-day gathering hosted by President Barack Obama. Among the stated purposes: discussing how to help African nations overcome systemic challenges, including disease.

Brantly and Writebol contracted Ebola after working on the same medical mission team treating victims of the virus around Monrovia, Liberia. More than 1,300 people have been stricken, killing at least 729 of them in Liberia, Guinea and Sierra Leone.

Ebola has no vaccine or antidote. However, both Brantly and Writebol were given an experimental treatment last week, according to international relief group Samaritan's Purse. Brantly is a physician with the group, and the group originally said that only Writebol got the treatment. Brantly also received a unit of blood from a 14-year-old boy, an Ebola survivor, who had been under his care, according to the organization.

Emory, where Brantly already is quarantined, boasts one of the nation's most sophisticated infectious disease units. Patients are sealed off from anyone not in protective gear. Lab tests are conducted inside the unit, ensuring that viruses don't leave the quarantined area. Family members see and communicate with patients through barriers.

Writebol and her husband, David, had been in Liberia since August 2013, sent there by the Christian organization SIM USA and sponsored by their home congregation at Calvary Church in Charlotte, North Carolina.

At the hospital where Brantly treated patients, Nancy Writebol worked as a hygienist whose role included decontaminating those entering or leaving the Ebola treatment area. Their pastor, the Rev. John Munro, said David Writebol fulfilled administrative and technical duties.

A few weeks before she was diagnosed, Jeremy Writebol said, a doctor visited the Monrovia hospital where she worked and praised the decontamination procedures as the best he'd seen. Jeremy Writebol said she was "really pleased by knowing that" and never thought she would be infected, despite her proximity to the virus.

David and Nancy Writebol have engaged in foreign missions for 15 years, spending five years in Ecuador and nine years in Zambia, where Munro said they worked in a home for widows and orphans.

After talking with his father Sunday, the younger Writebol said it's clear his mother "is still suffering," but said the family remains optimistic.

Writebol has now received two doses of an experimental treatment and is showing marked improvement, said Palmer Holt, a spokesman for SIM, the aid organization for which she works.

On Sunday, she was in stable but serious condition. On Monday, she was walking with assistance, Holt said.

"Her husband, David, told me Sunday her appetite has improved and she requested one of her favorite dishes - Liberian potato soup - and coffee," Bruce Johnson, president of SIM USA, said in a statement Monday.

Officials at the U.S. Centers for Disease Controls and Prevention, also in Atlanta, say they've gotten some blowback for bringing Ebola cases to an American hospital. But Dr. Tom Frieden, CDC director, emphasized again Sunday that there is no threat to the public in the United States.

Some airlines that serve those nations have suspended flights, while international groups, including the Peace Corps, have evacuated some or all representatives in the region.

But the Writebols, their pastor predicted, won't be away from the stricken land for any longer than they have to be.

"They knew that Liberia was a tough assignment," he said, comparing their vocation to the Bible's stories of leper colonies.

"Followers of Christ went into those colonies, knowing they would die," Munro said. "I certainly wouldn't judge them if they didn't go back, but I don't think this will deter them."