A nurse in Spain has become the first health worker to be infected with the Ebola virus outside of West Africa, raising serious concerns about how prepared Western nations are to safely treat people with the deadly illness, New York Times reported.

The nurse contracted the illness while treating a Spanish missionary who was infected in Sierra Leone and flown to Madrid’s Carlos III hospital, where he died on Sept. 25, Spain’s Health Ministry said. The priest, Manuel García Viejo, died three days after being flown back to Spain, and the nurse entered his room only twice, including once after his death, according to Antonio Alemany, a health official from the regional government of Madrid.

Situated close to the highway that circles the Spanish capital, the Carlos III hospital is tied to the much larger La Paz hospital in Madrid, but it was selected because it has long specialized in researching H.I.V. and other infectious as well as tropical diseases. In August, an entire floor of the hospital was sealed off and turned into an isolation unit, initially to treat Miguel Pajares, another Spanish priest who had been working in Africa and was the first European to be repatriated after being infected with Ebola. Father Pajares died on Aug. 12, five days after entering the special unit.

Antonio Alemany, a health official from the regional government of Madrid, told the news conference that the nurse went on vacation a day after Father García Viejo died. She got in touch with a medical center on Sept. 30 after feeling feverish, but had been leading “a normal life” while on vacation, he added, without giving details on her whereabouts during that period.

She has been kept in isolation in a hospital in Alcorcón, on the outskirts of Madrid, but not in a unit specialized to treat infections like Ebola. She was transferred to the Carlos III hospital late Monday.