Brussels - The EU said Tuesday it has asked Spain to explain how a nurse treating Ebola patients in Madrid contracted the deadly disease, the first known case of transmission outside Africa.
The European Commission "sent a letter Monday to the Spanish health minister to obtain some clarification" of how this had happened, despite all the precautions taken, a spokesman said.
"There is obviously a problem somewhere," Commission spokesman Frederic Vincent said, at a time when all European Union member states are supposed to have taken measures to prevent an Ebola outbreak.
Tests confirmed that the nurse had been infected with the deadly virus that has killed more than 3,400 people in west Africa.
Spanish health officials are now trying to find out whom she may have come into contact with and are monitoring 30 people -- including her co-workers and husband -- closely for symptoms of the deadly disease.
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The woman was part of a medical team at Madrid's La Paz-Carlos III hospital that treated two elderly Spanish missionaries who died of Ebola shortly after they were repatriated from Africa.
Vincent said that despite the case, the Commission was not unduly concerned and believed that the spread of the virus in Europe "remains highly unlikely."
The Commission, however, hopes that Spain will provide details by Wednesday so that they can be discussed by European Union officials.
The case "may even in some way serve as a lesson for other member states," Vincent said, noting that the Madrid hospital involved had been designated as a special Ebola treatment centre.
The nurse, who is married without children, is now being treated in isolation at a hospital in Alcorcon, a southern Madrid suburb, where she is said to be in a stable condition although still running a fever.
Europe and the United States have been touched by the disease but until now all the cases stemmed from people who caught the virus in west Africa and who then returned home.