ATLANTA (CNN) - A second American suffering from Ebola is expected to arrive in Atlanta on Tuesday from Liberia, where she contracted the deadly virus.
Missionary Nancy Writebol will travel aboard an air ambulance equipped with an isolation unit. It will land at Dobbins Air Reserve Base, and from there she'll be rushed to Atlanta's Emory University Hospital about 20 miles away.
Writebol is one of two Americans stricken with the disease while aiding Ebola victims in the latest outbreak in West Africa. Ebola has killed more than 700 people in three nations: Guinea, Liberia and Sierra Leone.
Their evacuation to Atlanta marks the first time anyone infected with the virus has been known to get treatment in the United States.
Both patients will be treated at an isolation unit where precautions are in place to prevent it from spreading, unit supervisor Dr. Bruce Ribner said.
The first American evacuee, Dr. Kent Brantly, was making progress since he arrived in Atlanta from Liberia on Saturday, a U.S. official said.
"It's encouraging that he seems to be improving," Thomas Frieden, director of the Centers for Disease Control and Prevention, told CBS' "Face the Nation."
"That is really important, and we are hoping he will continue to improve."
Brantly, 33, is the first known patient with the deadly virus to be treated on U.S. soil. He landed at Dobbins and was quickly rushed to Atlanta's Emory University Hospital.
Ebola doesn't spread through airborne or waterborne methods. It spreads through contact with organs and bodily fluids such as blood, saliva, urine and other secretions of infected people.
There is no FDA-approved treatment for Ebola, and Emory will use what Ribner calls "supportive care." That means carefully tracking a patient's symptoms, vital signs and organ function and taking measures, such as blood transfusions and dialysis, to keep patients stable.
Elsewhere, a patient at Mount Sinai Hospital in New York City was being tested after being admitted to the facility with a high fever and gastrointestinal symptoms, according to a statement from the hospital on Monday.
He had recently traveled to a country in West Africa where Ebola has been reported. The patient was placed in strict isolation, and doctors are working to determine the cause of his symptoms. They expect to get test results back in a day or so.
"(The) likelihood is pretty low" the patient has Ebola, said CNN's Dr. Sanjay Gupta. About half a dozen people have recently returned from West Africa and gotten tested because of symptoms consistent with the disease. None of those cases has been confirmed as Ebola, Gupta said.
The Ebola virus causes viral hemorrhagic fever, which refers to a group of viruses that affect multiple organ systems in the body and are often accompanied by bleeding.
Early symptoms include sudden onset of fever, weakness, muscle pain, headaches and a sore throat. They later progress to vomiting, diarrhea, impaired kidney and liver function -- and sometimes internal and external bleeding.
Emory's isolation unit aims to optimize care for those with highly infectious diseases and is one of four U.S. institutions capable of providing such treatment.
CNN's Jason Carroll contributed to this report.
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