Prime Minister Mariano Rajoy appealed for calm over Spain’s Ebola outbreak and pledged to step up efforts to contain the virus as more health staff were isolated for monitoring.

“Let the professionals do their work, let’s trust our professionals,” Rajoy said in Congress today. “What we have to do right now is be alert but stay calm -- this is the government’s position.”

A nursing assistant who helped care for two missionaries repatriated to Madrid for Ebola treatment was diagnosed with the disease two days ago, raising concerns about Spain’s hospital procedures. The health worker’s case, the first known instance of Ebola contracted outside Africa, shows that medical staff must exercise every caution when treating Ebola, said Peter Piot, a co-discoverer of the virus in 1976 who is now the director of the London School of Hygiene & Tropical Medicine.

Two more nursing workers have been admitted to hospital for isolated monitoring after complaining of low fevers, a spokeswoman for the La Paz-Carlos III hospital complex in Madrid said today by phone. They join the nursing assistant, her husband, who is being monitored but has no symptoms, and another nurse whose initial tests for Ebola were negative.

About 52 people are being tracked because they interacted with the infected nursing assistant or cared for Ebola patients, hospital officials said yesterday. A traveler who arrived from Nigeria is also being monitored after a first negative test.

Minister’s Defense

Health Minister Ana Mato defended the government’s actions today in Congress, saying she would keep working to protect the Spanish public. A doctors’ union has called for her resignation.

“Without doubt we’re dealing with an issue that correctly worries public opinion,” Rajoy said. The government’s priorities are to treat patients, monitor all people in contact with the sick health worker and find out how her infection occurred.

The Ebola outbreak in Sierra Leone, Guinea and Liberia has killed more than 3,400 people, among them doctors and nurses caring for the sick. About 382 health-care workers have been infected in West Africa and 216 of them have died, the World Health Organization said Oct. 3.

The virus is spread by direct contact with a sick person’s blood or other bodily fluids, suggesting that infection control procedures weren’t strictly followed at Carlos III in Madrid. While sporadic cases of Ebola in Europe are unavoidable, the risk of the disease spreading on the continent is extremely low, the World Health Organization said in an e-mailed statement today.

Hospital Training

“The investigation will have to look into how prepared the hospital was since dealing with Ebola patients requires the best conditions of equipment, planning and training,” said Christophe Rapp, head of infectious and tropical diseases at the Begin military hospital in Saint-Mande, on the outskirts of Paris, which treated a volunteer nurse and discharged her last week.

The hospital will monitor employees who cared for her until Oct. 25, Rapp said. Those in contact with the Ebola patient wore special protection, dressing and undressing in pairs in front of mirrors to prevent mistakes, as a small quantity of virus is enough to trigger a secondary infection, he said. Other techniques to avoid contagion include human waste solidification as liquids are more dangerous to handle.

Nurses Vulnerable

“Nurse assistants are among the most exposed people in an Ebola case because they’re the ones in contact with human fluids when they change sheets or clean patients,” Rapp said. “Not any hospital can deal with Ebola patients, it’s a heavy, costly and complicated process, and if there had been no secondary infection until now, it’s also because there are so few cases.”

It’s still unclear how the nursing assistant became infected in Madrid, Rafael Perez-Santamarina, head of La Paz hospital, a university facility with which Carlos III hospital is affiliated, said yesterday. Spanish authorities didn’t identify her or her husband, though their names were published on social media and news websites.

Reporters gathered outside their home in Alcorcon on the outskirts of the Spanish capital last night, and two police cars were parked in front of the seven-story building. Television images today showed health officials arriving to do disinfection work at the building.

“It’s scary -- I would not have imagined having this so close to my house,” said Monica de Marcos, 44, while walking her dog nearby last night. “We have to pray and hope that nothing happens to her.”

Animal Roots

The Ebola virus jumps to humans from infected animals including chimpanzees, gorillas and bats. Aid workers who have fallen ill in Africa have been evacuated to Spain, France, Germany, the U.S. and Norway for treatment, raising concern that secondary infections will occur in those countries.

Manuel Garcia, a missionary doctor from the Hospital Order of Saint John of God, died Sept. 25 at Carlos III hospital after being repatriated from Sierra Leone. Miguel Pajares, a priest who contracted the illness in Liberia, died at the hospital in August.

In the U.S., a visitor from Liberia became the first case of Ebola diagnosed in that country and is being treated in Dallas, where he has been isolated since Sept. 28. He developed symptoms four days after he arrived. President Barack Obama has pledged to increase screening for Ebola-infected airline passengers.

Emory University Hospital in Atlanta and Nebraska Medical Center in Omaha have also treated Ebola patients, three of whom have been released after recovering. A fourth patient is under care in Omaha and a fifth in Atlanta.