The Spanish nurse who became the first person to contract Ebola in Europe has said she followed all protocols and does not know how she became infected with the virus.

Teresa Romero Ramos, who helped treat two Spanish missionaries who died after returning from Africa with Ebola, tested positive for the disease on Monday.

In a brief interview with Spanish newspaper El Mundo, the nurse was asked how she may have fallen ill, to which she replied: "I really can't say, I haven't the slightest idea."

Asked whether she followed the safety protocol, Mrs Romero Ramos said: "Yes, I did."

Dozens of doctors and nurses yesterday demonstrated outside La Paz Hospital, in Madrid, demanding more information about how Mrs Romero Ramos caught Ebola.

The disease is not airborne but transmitted through direct contact with the body fluids of a person who, experts say, must already be showing symptoms.

See the Ebola outbreak mapped Show all 7 1 /7 See the Ebola outbreak mapped See the Ebola outbreak mapped 25 March 2014 This outbreak of the Ebola virus first emerged in the Guéckédou region of Guinea, at a crossroads with both Liberia and Sierra Leone See the Ebola outbreak mapped 31 March On 31 March the WHO confirmed the outbreak was now international, spreading first into Liberia's northern-most Lofa region See the Ebola outbreak mapped 27 May The virus spread to Sierra Leone at the end of May - just as agencies were hoping the worst was over See the Ebola outbreak mapped 27 July In Sierra Leone the virus boomed, and then it spread to Nigeria when the Liberian diplomat Patrick Sawyer flew from Monrovia to Lagos See the Ebola outbreak mapped 9 August The Nigeria cases sparked fears around the world, and there have now been deaths in Spain and Saudi Arabia involving people who had travelled to West Africa. The numbers of cases continue to rise See the Ebola outbreak mapped 17-20 September In mid-September, Senegal confirmed its first case linked to the Ebola outbreak, a development the WHO described as a top priority emergency. Numbers of cases continued to grow exponentially in Guinea, Sierra Leone and Liberia, as experts warned they could number one million by January if not contained See the Ebola outbreak mapped 8 October Two cases of Ebola have now been reported in the US and Europe - the first times the virus has been contracted among health workers outside Africa

In a statement, the Madrid College of Doctors said: "Given that both the transmission methods and the methods of prevention are well known, it is clear that some mistake was made."

Rafael Perez-Santamaria, head of the Carlos III Hospital in Madrid, where a team including Mrs Romero Ramos treated the two missionaries, said medical staff were "revising our protocols".

Four people including the nurse's husband have been admitted to hospital for observation. One of the four, another nurse, who had diarrhoea but no fever, tested negative for the virus, a Spanish health source said.

The nurse's husband, Javier Limon Romero, has started a campaign to save his dog after Madrid's regional government ordered for the pet to be put down.

Animal welfare groups have shared a note from Mr Romero online in which he argues the dog could be placed in quarantine if authorities are worried it may spread Ebola.

Mrs Romero Ramos had gone on holiday after the second of her Ebola patients died on September 25, although authorities have said she did not leave the city.

She started to feel ill on 30 September. Her trade union said she had then asked three times to be tested for Ebola before the infection was finally confirmed on Monday.