AFP/Washington

US President Barack Obama urged against "hysteria or fear" on Saturday in the face of a growing Ebola crisis, as the United Nations spoke of an "encouraging" response to its funding appeal.

The worst-ever outbreak of the deadly virus has so far killed more than 4,500 people, mainly in three West African nations at the epicentre of the outbreak: Guinea, Liberia and Sierra Leone.

Obama's warning came a day after the World Bank warned the battle against the disease was being lost and as the US president named an "Ebola czar" to coordinate Washington's response.

A UN appeal for nearly $1 billion to fight the spread of the disease has so far fallen short, but a spokesman told AFP more money was coming in daily.

Out of $988 million requested a month ago, the UN said Saturday $385.9 million had already been given by a slew of governments and agencies, with a further $225.8 million promised.

"It has been encouraging to see the amount and the speed with which these amounts have been committed," said Jens Laerke, spokesman for the UN's humanitarian office (OCHA).

"To be honest, I don't recall during my time at OCHA that we have had such a response within a month for a billion-dollar appeal."

Nevertheless, Laerke said, this wasn't a sign the need for donations had passed.

"Nobody's smiling in this crisis, so I'm not going to go out and clap my hands and say everything is going fine, because it's not," he told AFP.

 

- Panic growing -

Meanwhile, as panic grows even far from the outbreak's epicentre, Obama counselled patience and perspective.

"This is a serious disease, but we can't give in to hysteria or fear -- because that only makes it harder to get people the accurate information they need. We have to be guided by the science," Obama said in his weekly address to the nation.

Friday saw a number of false alarms in the United States as fears grow, including at the Pentagon, where an entrance was closed after a woman vomited in a parking lot. US authorities later found no evidence that she had contracted Ebola.

"We have to remember the basic facts," Obama said Saturday.

The United States -- where a Liberian man died from Ebola on October 8 and two American nurses who treated him have tested positive -- was not seeing an "outbreak" or "epidemic," Obama stressed.

More "isolated" cases in the country were possible, he conceded. "But we know how to wage this fight."

The US president played down the idea of a travel ban from West Africa.

"Trying to seal off an entire region of the world -- if that were even possible -- could actually make the situation worse."

Travellers from affected regions would simply change their travel plans to evade screening, he said, making Ebola even harder to track.

 

- 'Losing the battle' -

Obama's call for calm was in stark contrast to World Bank chief Jim Yong Kim, who warned Friday: "We are losing the battle."

He blamed a lack of international solidarity in efforts to stem the epidemic.

"Certain countries are only worried about their own borders," he told reporters in Paris, as leaders in Washington and beyond grapple for a coordinated response to the outbreak.

Airports in several countries, including in the United States, have launched enhanced health checks in a bid to stop the spread of Ebola, although health experts -- including in the US -- have expressed doubts about their effectiveness.

France on Saturday started carrying out health checks on Air France passengers arriving from Guinea, where the epidemic began in December, while a union of the airline's flight attendants called for a halt in flights from Conakry altogether.

The United States, Britain and Canada have already launched screenings at airports for passengers from Ebola-ravaged zones. The EU is reviewing the matter.

As of October 14, 4,555 people have died from Ebola out of a total of 9,216 cases registered in seven countries, the World Health Organization says.

Symptoms of Ebola include fever, headache, diarrhea, vomiting and in some cases bleeding.

Even if a person is infected, the virus can only be passed on once symptoms appear and only through direct contact with their bodily fluids, such as mucus, semen, saliva, vomit, stool or blood.

There is no licensed treatment or vaccine for the contagious disease, but several countries are trying to develop an effective vaccine.