Spanish officials said they do not know what went wrong and are investigating.
"We are working to verify the exact source of contact to see if all strict protocols were followed," Spanish Health Minister Ana Mato said at a news conference on Monday, according to NBC News.
European Union officials have issued a letter to Mato asking for clarification about how the nurse became infected even though all EU member states were required to take measures to avoid transmission.
Health workers at the Carlos III Hospital protested on Tuesday, and others have raised concerns that the protective suits used by workers treating Ebola patients at the facility are not adequate. According to the Spanish newspaper El Pais, hospital staff provided photos of protective suits that use latex gloves attached using tape. Hospital staff members told the paper that the protective equipment should have been completely impermeable, but that it was not. The workers also said that the suits did not allow for autonomous breathing.
Hospital officials denied that World Health Organization recommendations were not followed in the treatment of both Garcia Viejo and another Spanish priest, 75-year-old Miguel Pajares, who died of Ebola after being flown from West Africa to Spain, where he received the experimental drug ZMapp.
“The suits used perfectly meet protocol, as well as the mandatory protection requirements for this disease," said Yolanda Fuentes, the deputy director of Carlos III hospital, according to El Pais.
The WHO recommendations detail, in general terms, the types of equipment that are appropriate for treating a patient with hemorrhagic fevers, including Ebola. The WHO also outlines procedures for entering and exiting an infected patient's room, removing protective equipment and decontaminating surfaces inside and outside a patient's room. Failure to follow any of the steps in those procedures could potentially lead to infection.
Hospital staff also alleged that waste from the patient's room was removed using an elevator that was shared by all hospital personnel, according to the Guardian.
The nurse who contracted Ebola began experiencing symptoms on Sept. 30, five days after Garcia Viejo died. Tests confirmed on Monday that she had contracted Ebola.
After treating both Garcia Viejo and Pajares, the woman went on a vacation but remained in Madrid, officials said, according to Reuters.
On Tuesday, 22 people who came into contact with the nurse were being monitored, but not isolated, according to Rafael Perez-Santamaria, head of the Carlos III Hospital.
The nurse's husband, who is not showing symptoms, and another health worker who is experiencing diarrhea but not fever, have been hospitalized. Early signs of Ebola infection include fever, diarrhea and headaches.
Officials "even announced plans to euthanize the woman's pet dog" in an effort the contain the virus, the AP reported.
Madrid's regional government even got a court order to euthanize and incinerate their pet, "Excalibur," against the couple's objections. The government said available scientific knowledge suggests a risk that the mixed-breed dog could transmit the virus to humans, and promised to use "biosecurity" measures to prevent any such transmission.
The incident has raised fresh concerns that, despite assurances from global public health officials that Ebola cases can be safely managed in developed countries, sufficient precautions have not been taken.
"Such imported cases and similar events as have happened in Spain will happen also in the future, most likely," said Zsuzsanna Jakab. "It is quite unavoidable ... that such incidents will happen in the future because of the extensive travel both from Europe to the affected countries and the other way around."
[This post originally cited an AP report that said a Nigerian has been hospitalized in Spain. The AP has updated its reporting to say that the man is Spanish and had recently traveled to Nigeria. This post has been updated as well.]