NEW YORK — In a case underscoring the perils of caring for Ebola patients, a nurse in Spain has come down with the disease — the first time the virus has spread outside West Africa during the current epidemic.

The nurse’s illness illustrates the danger that health care workers face not only in poorly equipped West African clinics, but also in the more sophisticated medical centers of Europe and the United States, said Dr. William Schaffner, an infectious disease expert at Vanderbilt University.

“At greatest risk in all Ebola outbreaks are health care workers,” he said.

The development came Monday as another American sick with the disease arrived back in the U.S. for treatment and President Barack Obama said the government was considering ordering more careful screening of airline passengers traveling from the outbreak region.

The unprecedented Ebola outbreak this year has killed more than 3,400 people in West Africa, and become an escalating concern to the rest of the world. It has taken an especially devastating toll on health care workers, sickening or killing more than 370 in the hardest-hit countries of Liberia, Guinea and Sierra Leone — places that already were short on doctors and nurses.

Ebola’s now in Europe: http://t.co/1TNEEknbwP pic.twitter.com/RWtCBhNlfB

— RYOT NEWS (@RYOTnews) October 7, 2014

The Spanish nurse was part of the medical team that treated a 69-year-old Spanish priest — Manuel Garcia Viejo — who died in a Madrid hospital late last month, Spain’s health minister said Monday.

The sick priest had been flown home from his post in Sierra Leone; the nurse is believed to have contracted the virus from him. She went to a Madrid hospital with a fever on Sunday, 10 days after the priest died, and was placed in isolation. She was transferred early Tuesday to Madrid’s Carlos III hospital, where the priest — and a second missionary priest sick with Ebola — were cared for until they died.

The World Health Organization confirmed there has not been a previous transmission outside West Africa in the current outbreak.

In the U.S., video journalist Ashoka Mukpo, who became infected while working in Liberia, arrived at the Nebraska Medical Center in Omaha, where another Ebola patient had been treated. It’s not clear how he was infected. It may have happened when he helped clean a vehicle someone died in, said his father, Dr. Mitchell Levy. On Monday, his symptoms of fever and nausea still appeared mild, Levy said.

“It was really wonderful to see his face,” said Levy, who talked to his son over a video chat system.

Mukpo is the fifth American sick with Ebola brought back from West Africa for medical care. The others were aid workers — three have recovered and one remains hospitalized.

VIDEO A nurse in Spain has contracted Ebola, the 1st known transmission outside of West Africa http://t.co/RfdrOfNTDw pic.twitter.com/QBXbVq17wT

— The National (@CBCTheNational) October 7, 2014

There are no approved drugs for Ebola, so doctors have tried experimental treatments in a few cases.

The critically ill Liberian man hospitalized in Dallas is also getting an experimental treatment, Texas Health Presbyterian Hospital said Monday. Thomas Eric Duncan is the first person to be diagnosed with Ebola in the U.S.; he was admitted to the hospital on Sept. 28, about a week after arriving in Texas.

The hospital said Duncan was receiving an experimental medication called brincidofovir, which was developed to treat other types of viruses. Laboratory tests suggested it may also work against Ebola.

Two other experimental drugs developed specifically for Ebola have been used, though it’s unclear whether they had any effect. The small supply of ZMapp was exhausted after being used on a few patients — though government officials say more should be available in the next two months. A second drug, TKM-Ebola from Tekmira Pharmaceuticals, has been used in at least one patient and is said to be in limited supply.

Schaffner noted there are many questions about the experimental medications, but their use is understandable — especially in a patient like Duncan who may be deteriorating.

“They’re trying to do anything they can to benefit the patient,” he said.

Meanwhile, Texas Gov. Rick Perry urged the U.S. government to begin screening air passengers arriving from Ebola-affected nations, including taking their temperatures. Perry stopped short of joining some conservatives who have backed bans on travel from those countries.

Federal health officials say a travel ban could make the desperate situation worse in those countries, and White House spokesman Josh Earnest said it was not currently under consideration.

Passengers leaving the outbreak zone are checked for fevers at the airport. Duncan was screened in Liberia, but he had no symptoms then, health officials have said. He also apparently had no symptoms when he arrived the next day, so a screening in the United States would not have detected his infection.

Health officials have said he didn’t get sick until four or five days later. The disease’s incubation period is 21 days

Airline crews and border agents already watch for sick passengers, and in a high-level meeting Monday at the White House, officials discussed potential options for screening passengers when they arrive in the U.S. as well.

Obama said the U.S. will be “working on protocols to do additional passenger screening both at the source and here in the United States.” He did not outline any details or offer a timeline.

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