Doctors at the isolation unit — the largest of four nationwide — will evaluate Mukpo before determining how to treat him. They said they will apply the lessons learned while treating American aid worker Rick Sacra in September. Sacra was successfully treated in the Nebraska unit and was allowed to return to his home in Massachusetts after three weeks, on Sept. 25.

Mukpo's father, Dr. Mitchell Levy, told NBC Sunday that his son was "counting the minutes" until he could leave Liberia, but that he was not feeling that ill Sunday. Levy said the family was traveling from Rhode Island to Nebraska.

"We are ready, willing and able to care for this patient," Smith said. "We consider it our duty to give these American citizens the best possible care we can."

The Nebraska hospital's biocontainment unit was created in 2005 specifically to handle this kind of illness, Dr. Phil Smith, who oversees the unit, said in a news release Friday.

He is the fifth American to return to the United States for treatment since the start of the latest Ebola outbreak , which the World Health Organization estimates has killed more than 3,400 people. Meanwhile, a Liberian man with Ebola who started showing symptoms while visiting the U.S. is in critical condition at a Dallas hospital.

Mukpo was working in Liberia as a freelance cameraman for NBC News when he became ill last week. Mukpo has written for Al Jazeera on the epidemic .

The specially equipped plane carrying Ashoka Mukpo landed at Eppley Airfield in Omaha at around 7:30 a.m. on Monday, where an ambulance was waiting to take him to the Nebraska Medical Center's specialized isolation unit.

A plane carrying an American journalist who contracted Ebola while working in Liberia landed Monday in Nebraska, where he will undergo treatment for the deadly disease.

Sacra received an experimental Tekmira Pharmaceuticals drug called TKM-Ebola, as well as two blood transfusions from another American aid worker who recovered from Ebola at an Atlanta hospital. The transfusions are believed to help a patient fight off the virus, because the survivor's blood carries antibodies for the disease. Sacra also received supportive care, including IV fluids and aggressive electrolyte management.

In Dallas, another man who recently traveled to the U.S. from Liberia was in critical condition Sunday. Thomas Eric Duncan has been hospitalized at Texas Health Presbyterian Hospital since Sept. 28. Dr. Tom Frieden, director of the federal Centers for Disease Control and Prevention, said he was aware that Duncan's health had "taken a turn for the worse," but he declined to describe Duncan's condition further.

The virus that causes Ebola is not airborne and can only be spread through direct contact with the bodily fluids — blood, sweat, vomit, feces, urine, saliva or semen — of an infected person who is showing symptoms.

Duncan arrived in Dallas on Sept. 20 and fell ill a few days later. His case has highlighted problems that American public health officials are trying frantically to address: The Dallas hospital that admitted him did not recognize the deadly disease at first and sent him home with antibiotics, only to have him return two days later in an ambulance.

"The issue of the missed diagnosis initially is concerning," Frieden said, adding that public health officials had redoubled their efforts to raise awareness of the disease.

Frieden said he was confident the disease would not spread widely within the U.S. Washington is also scaling up the U.S.'s response to the disease in West Africa, where Ebola presents an enormous challenge, he added.

Asked if the U.S. should suspend flights to and from affected countries or impose a visa ban on travelers from those areas, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said "absolutely not."

"When you start closing off countries like that, there is a real danger of making things worse," he told "Fox News Sunday."

In Spain, a nurse who had been part of a team that treated two missionaries flown home to Madrid after becoming infected with Ebola in West Africa, was diagnosed with the disease. The nurse's only symptom was a fever, but the infection was confirmed by two tests, Spanish health officials said. She was being treated in isolation, while authorities drew up a list of people she had had contact with.

She is the first person known to catch Ebola outside the outbreak zone in West Africa.

Wire services