Health officials have said the nurse became infected while treating a missionary, Manuel García Viejo, who died in the Carlos III Hospital in Madrid on Sept. 25, after being repatriated from Sierra Leone. The officials said the nurse went on vacation the day after he died, then told a medical center that she had a fever of about 100 degrees on Sept. 30. She was hospitalized only on Monday, initially in another establishment without a unit specifically set up for handling diseases like Ebola.

The nurse’s husband has shown no signs of having the disease but was isolated as a precaution, said Dr. Francisco Arnalich, head of internal medicine at the hospital.

Reached by phone in his hospital ward, the nurse’s husband told the newspaper El Mundo that the couple had canceled vacation plans after he had an accident at work, and that his wife had decided to spend a few days at her mother’s instead. He did not specify where her mother lives. He said in the interview that he felt fine. But he said he was angered to hear that the medical authorities were recommending, as a precaution, that their dog be euthanized.

The husband, identified by the newspaper as Javier, said his wife, identified as Teresa, had told him that she followed all the safety instructions set by the hospital and did not know how she could have become infected. The case is worrisome because Spain is a developed country that is expected to have the rigorous infection controls needed to fight the spread of Ebola.