The first Ebola transmission case outside of Africa, involving a Spanish nurse who was treating an infected priest, has renewed concerns over the repatriation of those who become stricken with the deadly virus in West Africa.

Major questions remain as to how, exactly, the nurse contracted the disease after the Spanish priest was brought home from Sierra Leone for treatment. Health workers protested Tuesday as reports emerged that nurses in the unit had used tape to seal their latex gloves and that their protective suits weren't impermeable.

In the absence of answers, the case in Spain underscores the dangers of caring for Ebola patients, even in developed countries.

"We are taking this as an alert that we need to redouble our efforts to ensure U.S. healthcare facilities are ready to safely manage patients with Ebola," Abbigail Tumpey, spokeswoman for the Centers for Disease Control and Prevention, said via e-mail on Tuesday.

The CDC, she noted, will host training sessions in Alabama this week to teach West Africa-bound health-care providers how to work safely in Ebola treatment wards.

So far, five Ebola-infected Americans have been brought back to the United States from West Africa in specially equipped "air ambulances." Two remain hospitalized: One, who has not been identified, has been treated in an isolation unit at Emory University Hospital since Sept. 9, and another, an NBC News freelance cameraman, arrived at Nebraska Medical Center on Monday.

A Norwegian doctor who became stricken with Ebola while working in Sierra Leone was medevaced to Norway on Tuesday, and a French nurse who contracted Ebola while volunteering with Doctors Without Borders was released from a French hospital over the weekend.

As opposed to the case in Dallas, where Thomas Eric Duncan was diagnosed after traveling from Liberia to the United States through Brussels, the repatriated patients are not people who showed up at U.S. or European emergency rooms unannounced, testing the ability of those facilities to identify a potential Ebola case.

In these cases, hospital officials and health-care workers were expecting Ebola patients, and, in theory, have been prepared to minimize the risk of transmission while caring for them.

Shelly Schwedhelm, nursing director of Nebraska Medical Center's bio-containment unit, said on Tuesday that she doesn't believe it’s possible for a fate similar to the Spanish nurse's to befall one of her staff members or colleagues. “There are always things that can happen, but I feel very comfortable and confident with the personnel and the procedures in the unit,” she said.

But similar situations to the Spanish case are "unavoidable" and "will happen also in the future, most likely," the World Health Organization’s European regional director Zsuzsanna Jakab told Reuters.

"The unfortunate news that's going on in Spain, it can't help but increase some of that anxiety that's going on right now," David Lakey, commissioner of the Texas Department of State Health Services, said on a conference call with reporters Tuesday. Lakey emphasized that Texas medical personnel are being extremely careful in treating Duncan.

At the Nebraska facility, someone constantly monitors caregivers as they're putting on and removing protective gear, to ensure it’s done properly and in the right order. Gear includes head covers, respirators, gowns, boots, "triple gloves" and visors. All waste from the bio-containment unit is run through a large medical sterilizer called an autoclave.

The Spanish case was briefly discussed in the Nebraska team’s morning huddle Tuesday. But, Schwedhelm said: "Honestly, they’re eager to know what happened, but there are absolutely no concerns for themselves at the moment."

Those working with the repatriated patients in Nebraska -- there are more than 40 of them on the team, Schwedhelm said  -- volunteered for Ebola detail and went through an application process. Many staff members were “eager to get back in the unit” Monday when the center received its newest patient, NBC News cameraman Ashoka Mukpo. The facility's first Ebola patient, missionary doctor Richard Sacra, was discharged late last month.

There are far more West African medical and aid workers than foreign nationals treating Ebola patients on the front lines of the outbreak; Doctors Without Borders alone has about 3,000 in the region, compared to about 250 foreign nationals.

But, public health officials say, allowing for the possibility of repatriation in the event of an infection is a critical recruitment tool as global aid organizations struggle to enlist foreign health-care workers and volunteers.

“We still need to continue the measures for evacuation of staff because we recognize that there's an extraordinary burden carried by health workers and doctors working on Ebola,” WHO spokesman Daniel Epstein said. “They're at the forefront of fighting [the disease].”

The United States could see more American patients brought back home; if any U.S. service members contract Ebola during the military's operation in West Africa, they will be brought back to the United States for treatment, Gen. David Rodriguez, the chief of U.S. Africa Command, said Tuesday.

A few voices have come out against bringing Ebola-infected Americans back for treatment. Among those critical of the repatriation of infected aid workers: Donald Trump and Ben Carson. But the public outcry here has been limited.

In contrast, there was widespread controversy in Spain when that nation repatriated a priest from West Africa to the Carlos III Hospital in Madrid, with health-care workers saying the country was ill-equipped to treat him.

Daniel Bernabéu, the president of Spain’s doctors’ trade union, called the move "political rather than health-related," the Guardian reported at the time. He also pointed out that Spain had just one hospital with adequate bio-safety measures -- and that even there, the safety measures lagged behind those found in numerous U.S. hospitals.

In August, after the first repatriated American Ebola patients were discharged in Atlanta, Bruce Ribner, medical director of Emory’s Infectious Disease Unit, said: "We were very hopeful that with the level of support we can deliver in our facility, that we would have a substantially better outcome than our colleagues practicing with lesser developed health care systems."

Ribner, who led the team that treated doctor Kent Brantly and missionary worker Nancy Writebol, noted that the lessons learned in caring for those two patients would "help advance the world's understanding of how to treat Ebola virus infections, and hopefully to improve survival in parts of the world where patients with this infection are treated."

And, he declared: "It was the right decision to bring these patients back to Emory for treatment."

On Tuesday, in Omaha, Nebraska Medical Center's Schwedhelm said she felt similarly about treating Sacra and, now, Mukpo.

"These are Americans and we want to be able to provide them with the best care possible," she said. "I feel very confident, and in doing that, we're fulfilling our role and responsibility. That's what I trained for."​

Mark Berman contributed to this report.

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