In West Africa, a second American who contracted Ebola while helping patients was expected in Atlanta, while a New York hospital was testing a man with symptoms of the virus.
The medical evacuation plane carrying missionary Nancy Writebol from Liberia to Dobbins Air Reserve Base is equipped with a special containment unit, her charity SIM said.
It brought Kent Brantly of Samaritan's Purse, who had worked on a joint team with Writebol, to Emory University Hospital on Saturday.
After the plane lands, Writebol will be transported to Emory University Hospital by ambulance and placed in a special isolation unit set up in collaboration with the Centers for Disease Control and Prevention where Brantly is also receiving treatment.
Both patients are receiving an experimental serum but SIM USA president Bruce Johnson said it was having less of an effect on Writebol, who is 60 years old.
"Nancy received her second dose today. The indication is that it did not have quite the impact on Nancy as it did Kent," he said.
"This disease really can weaken the body and Kent is much younger than Nancy. And so, we're just grateful and very cautiously optimistic about how she's doing right now."
The United States had never before recorded cases of Ebola on US soil.
Writebol and Brantly had both been working to help those affected by an epidemic that has now killed nearly 900 people so far this year, according to the World Health Organization.
Upon his arrival in Atlanta, Brantly had stepped off an ambulance gingerly but walking. But Johnson said he didn't expect the same from Writebol, who is in more serious condition.
"Medical doctors there on site caring for her is that she's in a more weakened condition," Johnson told CNN on Monday.
"However, today has been a good day. Matter of fact, her husband, David, told me that her appetite is returning and she asked for her favorite Liberian meal, potato soup, which is a great sign."
He expressed hope that bringing the two patients to the United States and treating them there would help advance research into Ebola to address a crisis in countries like Liberia, where there are only about 50 doctors for four million people.
- New York patient -
The New York patient was admitted to hospital with high fever and grastrointestinal symptoms similar to those of Ebola, but doctors said it was likely not the deadly disease this time.
The man had recently traveled to West Africa.
"Odds are this is not Ebola. It's much more likely it's a much more common condition," said Mount Sinai Hospital president David Reich, noting that testing and confirmation with the Centers for Disease Control in Atlanta would take 48-72 hours.
He said the patient was "promptly isolated and placed in a strict isolation facility.
The World Bank has pledged up to $200 million to Guinea, Liberia and Sierra Leone to help the West African nations contain the deadly outbreak.