ATLANTA — A plane carrying an American doctor stricken with Ebola after treating patients in Liberia landed briefly in Bangor on Saturday morning to refuel, Bangor International Airport Director Tony Caruso confirmed early Saturday afternoon.

The small Gulfstream jet landed around 7:30 a.m., taxied to the customs clearance area, refueled and took off for Atlanta about 45 minutes later, Caruso said.

City officials were notified of the scheduled refueling stop Friday, to put them on alert in case anything unexpected happened, according to City Council Chairman Ben Sprague.

Caruso called the refueling stop a “standard technical operation” and said no airport staff came in contact with passengers on the flight.

Officials announced Friday that two American aid workers, both seriously ill after being infected with the deadly Ebola virus in Liberia, would be flown to the United States and treated in isolation at an Atlanta hospital.

Shortly before noon Saturday, the chartered medical aircraft carrying Dr. Kent Brantly touched down at Dobbins Air Reserve in Marietta, Georgia, a base spokesman said.

Dr. Thomas Frieden, director of the U.S. Centers for Disease Control in Atlanta, said the federal agency would help ensure there is no risk of the virus spreading as the workers are transported and emphasized Ebola was not transmissible through casual contact. He also expressed hope on CNN that “irrational fears do not trump our compassion.”

“Ebola is a huge risk in Africa,” Frieden told CNN. “It’s not going to be a huge risk in the U.S.”

Dr. Brantly improving

Frieden said Sunday that Brantly was improving. He was able to walk, with help, from an ambulance after he was flown on Saturday to Atlanta, where he is being treated by infectious disease specialists at Emory University Hospital.

“It’s encouraging that he seems to be improving — that’s really important — and we’re hoping he’ll continue to improve,” said Frieden.

Frieden told CBS’s “Face the Nation” it was too soon to predict whether Brantly would survive, and a hospital spokesman said later that Emory did not expect to provide any updates on the doctor’s condition on Sunday.

Brantly is a 33-year-old father of two young children who works for the North Carolina-based Christian organization Samaritan’s Purse. He was in Liberia responding to the worst Ebola outbreak on record when he contracted the disease.

Since February, more than 700 people in West Africa have died from Ebola, a hemorrhagic virus with a death rate of up to 90 percent of those infected. The fatality rate in the current epidemic is about 60 percent.

A second U.S. aid worker who contracted Ebola alongside Brantly, missionary Nancy Writebol, will be brought to the United States on a later flight as the medical aircraft is equipped to carry only one patient at a time.

Standard treatment for the disease is to provide supportive care. In Atlanta, doctors will try to maintain blood pressure and support breathing, with a respirator if needed, or provide dialysis if patients experience kidney failure, as some Ebola sufferers do.

Writebol, a 59-year-old mother of two who worked to decontaminate those entering and leaving an Ebola isolation unit in Liberia, was due to depart for the United States overnight on Monday, Liberia’s information minister said.

Writebol’s husband, David, who had been living and working in Liberia with his wife, was expected to travel home separately in the next few days, their missionary organization, SIM USA, said in a statement.

Despite public concern over bringing in Ebola patients, the CDC’s Frieden said the United States may see a few isolated cases in people who have been traveling but did not expect widespread Ebola in the country.

The facility at Emory chosen to treat the two infected Americans was set up with the CDC and is one of four in the country with the ability to handle such cases.

The Americans will be treated primarily by four infectious disease physicians, and will be able to see relatives through a plate-glass window and speak to them by phone or intercom.

Frieden said it was unlikely that Brantly’s wife and children, who left Liberia before he began showing symptoms, had contracted the disease because people who are exposed to Ebola but not yet sick cannot infect others.

The CDC has said it is not aware of any Ebola patient having been treated in the United States previously. Five people entered the country in the past decade with either Lassa Fever or Marburg, both hemorrhagic fevers similar to Ebola.

President Barack Obama said last week some participants at an Africa summit in Washington this week would be screened for Ebola exposure. Frieden said on Sunday there was no reason to cancel the event.

“There are 50 million travelers from around the world that come to the U.S. each year that are essential to our economy, to our families, to our communities. We’re not going to hermetically seal this country,” he told Fox News Sunday.

BDN reporter Nick McCrea contributed to this story.