ATLANTA - The second American aid worker who contracted the Ebola virus in West Africa was expected to arrive in Atlanta on Tuesday in serious condition, while a New York hospital was testing a man with symptoms of the deadly disease.

New York's Mount Sinai Hospital on Manhattan's Upper East Side said on Monday it was testing a man who traveled to a West African nation where Ebola has been reported. The man, who had a high fever and gastrointestinal symptoms, had been placed in strict isolation and was being screened to determine the cause of his symptoms.

The New York patient added to concerns about the often fatal disease after two American healthcare workers contracted it in West Africa, where they had traveled to help fight the disease that has killed nearly 900 people since February.

Missionary Nancy Writebol, 59, will fly on a medical aircraft from Liberia to be treated by infectious disease specialists in a special isolation ward at Emory University Hospital in Atlanta, according to Christian mission group SIM USA.

Emory's specialists on Saturday began treating 33-year-old U.S. doctor Kent Brantly, who also returned home after being stricken with Ebola during the emergency response to the worst outbreak on record of the hemorrhagic virus.

Writebol and Brantly are believed to be the first Ebola patients ever treated in the United States. They served in Monrovia on a joint team run by Christian aid groups SIM USA and Samaritan's Purse and are returning separately because the plane equipped to transport them can carry only one patient at a time.

Writebol was in serious condition, SIM USA said on Monday.

"Her husband 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.

Meanwhile, Brantly's wife, who had returned home to Texas before he became ill, said in a statement late on Sunday that she had seen her husband and that he was in good spirits.

"He thanked everyone for their prayers and asked for continued prayer for Nancy Writebol's safe return and full recovery," Amber Brantly said.

SIM said a missionary group of two adults and six children it evacuated from Liberia due to the outbreak arrived on Sunday in Charlotte, North Carolina, where they will be housed temporarily on the organization's campus. None have shown symptoms of infection, the group said.

EXPERIMENTAL DRUG

Both Brantly and Writebol saw their conditions improve by varying degrees in Liberia after they received an experimental drug previously tested only on monkeys, said a representative for Samaritan's Purse.

The drug was developed by San Diego-based private biotech firm Mapp Biopharmaceutical Inc. Shares for another company, Canada-based Tekmira Pharmaceuticals Corp, one of a few to have developed Ebola treatments advanced enough to be tested on people, slumped after media reports about the Mapp drug.

There is no proven cure for Ebola, and the death rate in the current epidemic is about 60 percent, experts say.

Standard treatment for the disease is to provide supportive care. Doctors at Emory will try to maintain blood pressure and support breathing of the workers, with a respirator if needed, or provide dialysis if they experience kidney failure, as some Ebola sufferers do.

White House spokesman Josh Earnest said there were no plans to stop flights to the United States from countries grappling with Ebola. Screening is being done to watch for travelers exhibiting symptoms, including some participants at a U.S.-hosted Africa summit in Washington.

Brantly and Writebol each had lived in Liberia since last year with their spouses and, in Brantly's case, two young children.

Brantly joined the Samaritan's Purse post-residency program after completing his residency in family medicine at John Peter Smith Hospital in Fort Worth, Texas, and then became part of the organization's medical team helping to fight Ebola.

Writebol, a mother of two from Charlotte, is a longtime missionary who had been working for SIM USA as a hygienist who decontaminated the protective suits worn by medical workers inside the isolation ward at a treatment center in Monrovia.