The United States and Canada announced stepped-up airport screening measures on Wednesday to look for passengers carrying Ebola, as the deadly virus killed a man in Texas and the worldwide toll neared 3,900.

The spillover of the virus - with the first diagnosis in US and the first case of infection in Spain - has raised fears of contagion in the West.

Speaking hours after the first US Ebola patient, Thomas Eric Duncan, was pronounced dead in a Dallas hospital, US President Barack Obama instructed local authorities to precisely follow federal guidelines to prepare for a potential case of Ebola. He said it was crucial to respond with "an appropriate sense of urgency."

On Thursday, health officials said two doctors who treated a Spanish nursing assistant diagnosed with Ebola have been admitted to a Madrid hospital for precautionary observation, bringing to six the number being monitored at the center.

In Australia, health authorities confirmed on Thursday that a 57-year-old woman was being assessed in a hospital in Queensland state for the deadly Ebola virus.

Queensland's chief health officer Jeanette Young told a news conference that the woman recently returned from Sierra Leone, where she has been working in a hospital treating Ebola victims.

The world's largest outbreak of Ebola has killed 3,865 people out of 8,033 infected so far this year, mainly in Liberia, Sierra Leone and Guinea, according to the World Health Organization's latest count.

But the WHO sought to contain concerns of a wider outbreak in Europe after a Spanish nurse was infected, with regional director Zsuzsanna Jakab saying sporadic cases in Europe were "unavoidable", but the risk of a full outbreak was "extremely low".

In Washington, officials announced increased screening at five major airports - New York City, Washington, Chicago, Atlanta and Newark, New Jersey.

And Canadian health minister Rona Ambrose said passengers arriving from West African countries affected by the epidemic must go through tightened controls, though she didn't specify where these would take place.

Meanwhile, two people were hospitalized in Los Angeles and Dallas, Texas, for possible exposure to Ebola.

The Los Angeles case, concerning a patient who had traveled to Liberia, turned out to be a false alarm.

In the Dallas case, US Centers for Disease Control and Prevention chief Tom Frieden said, "There is someone who does not have either definite contact with Ebola or definite symptoms of Ebola who is being assessed."

Ebola is transmitted by close contact with the bodily fluids of a person who is showing symptoms of infection such as fever, aches, vomiting and diarrhea, or who has recently died of the hemorrhagic virus, experts say.

The leaders of three Ebola-stricken West African nations are meeting with heads of the United Nations, the International Monetary Fund and the World Bank to discuss the outbreak and what help they need to fight it.

Alpha Conde of Guinea, Ellen Johnson Sirleaf of Liberia and Ernest Bai Koroma of Sierra Leone meet on Thursday with UN Secretary-General Ban Ki-moon, IMF Managing Director Christine Lagarde and World Bank President Jim Yong Kim.

The Ebola summit coincides with the fall meetings of the IMF and World Bank in Washington.

AP - AFP - Xinhua

(China Daily 10/10/2014 page12)