DALLAS - The Ebola panic went up a notch yesterday as the first patient diagnosed on American soil died and it emerged that a mere touch on her face could have infected a Spanish nurse.

Mr Thomas Duncan, a Liberian man who had travelled to the United States while carrying the virus, died after several painful days of struggle at a Dallas hospital.

Mr Duncan had contracted the disease while helping a patient in his home country. He managed to pass through airport checks and it was only while he was in the US that his condition worsened.

Dozens of people that he came into contact with have since been placed under quarantine.

Meanwhile, in Spain, a nurse who has been identified as Ms Teresa Romero was possibly infected when she touched her face with a glove as she removed her protective suit after treating a missionary who had the deadly virus, a doctor treating her said yesterday.

The possible explanation of how the first case of Ebola was transmitted outside of West Africa came as the number of people now quarantined in Madrid reached six and a prominent World Health Organisation (WHO) official warned that more cases could be expected among health-care workers - even in developed countries with modern medical systems.

Ms Romero, in her 40s, had cared for two elderly Spanish missionaries who died from the virus following their return from West Africa.

Officials said they were monitoring as a precaution 52 other people - mostly health staff - who had been in contact with the infected nurse.

But yesterday, Dr German Ramirez, who is treating Ms Romero at Madrid's Carlos III hospital, said she recalled that she might have had contact with her face after leaving an Ebola patient's isolation room. "During the course of the morning we looked at actions taken when (Ms Romero) put on her protective suit," Dr Ramirez said. "She has told us of the possibility that her suit had contact with her face... It could have been an accident. It looks like it was the gloves."

Ms Romero became infected when she was treating Mr Manuel Garcia Viejo, a priest who contracted the virus in West Africa. She entered his room only twice, once to change his diaper, and a second time to remove his belongings after he died on Sept 25.

She began experiencing symptoms of Ebola on Sept 30, but was admitted to the hospital only on Sunday. Tests confirmed on Monday that she had Ebola.

Professor Peter Piot, a prominent WHO adviser and an Ebola specialist, said he was not surprised at Ms Romero's case even though experts had emphasised the poor health-care systems of the countries hardest hit by the virus in West Africa.

Modern hospitals with rigorous disease control measures would prevent infection, it was believed. But the case of Ms Romero proves that is far more difficult than many thought, the BBC said.

Ebola has killed 3,439 people in West Africa since the start of the year, according to the latest WHO toll, with health workers making up around 6 per cent of victims.

Meanwhile, the US authorities yesterday announced tougher Ebola screening at American airports, CNN reported. Travellers arriving from Ebola-stricken Liberia, Sierra Leone and Guinea will face mandatory screening measures for the deadly virus as soon as this weekend, it reported yesterday, citing the US government.

AGENCE FRANCE-PRESSE, REUTERS, WASHINGTON POST