New York's JFK airport has started screening to try to stem the Ebola outbreak that has killed more than 4,000 people.

Passengers from Liberia, Sierra Leone and Guinea - the worst-hit countries - will have their temperatures taken and have to answer a series of questions.

Checks at O'Hare in Chicago, Newark, Washington's Dulles and Atlanta's airport will begin in the coming days.

This comes after the first person died of Ebola in Texas on Wednesday.

Thomas Duncan had travelled to the US from Liberia, and was only diagnosed with the disease once he arrived in Dallas.

The latest figures released by the World Health Organization show the number of deaths attributed to the the haemorrhagic fever has risen to 4,033.

The vast majority of the fatalities - 4,024 - were in the West African nations of Liberia, Sierra Leone and Guinea.

In other developments:

• Passengers at some British airports will be screened for Ebola
• The Moroccan government asks for next year's Africa Cup of Nations football tournament to be postponed because of the Ebola outbreak
• Liberia's senate elections due next week have been postponed to help reduce the risk of voters spreading the virus
• The Ebola crisis has resulted in the activation for the first time of the International Charter on Space and Major Disasters. Its normal role is to provide satellite imagery to make damage hazard-assessment maps
• The UN special envoy on Ebola, Dr David Nabarro, has warned that the world might have to live with the disease forever unless almost every country is mobilised to fight it

The screening measures at JFK started earlier today. Border agents will check passengers for signs of illness such as high temperatures.

Passengers from the three African nations will also be asked about their travel history prior to coming to the US and also if they have been in contact with anyone suffering from Ebola.

If they answer "Yes" to any questions or are running a fever, a representative of the Centers for Disease Control and Prevention (CDC) will intervene and provide a public health assessment.

There are currently no scheduled direct flights from the three countries to the US, with most passengers from Africa travelling via Europe.

All passengers travelling from airports in Sierra Leone, Guinea and Liberia are already being screened for symptoms when they depart.

Even if screening had already been in place in the US, Mr Duncan's case would not have been picked up as he only developed symptoms a week after he was back on US soil.

Experts have warned that a person can carry the virus for up to three weeks before showing symptoms.