The deadly Ebola virus could be mutating to become even more contagious, a leading U.S scientist has warned.

The disease has killed nearly 4,000 people, infecting in excess of 8,000 - the majority in the West African nations of Guinea, Sierra Leone and Liberia.

Communities lie in ruins, thousands of children have been orphaned, millions face starvation but the virus continues its unprecedented pace, invading and destroying vast swathes of these countries.

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A Liberian Red Cross burial team out on suits as they go to collect a suspected Ebola victim in Monrovia. A scientists has now warned that the virus could be getting even more contagious

The team make their way through the streets of Monrovia. The majority of Ebola victims have been in West Africa in countries such as Liberia, Sierra Leone and Guinea

A health worker escorts a mother and her baby from a holding centre in Monrovia into an ambulance for transport to a treatment centre

Meanwhile three nurses, two in the U.S. and one in Spain have caught the infection while treating Ebola patients, despite wearing protective suits.

Now U.S. scientist Peter Jahrling of the National Institute of Allergy and Infectious Disease believes the current Ebola outbreak may be caused by an infection that spreads more easily than it did before.

Dr Jahrling explained that his team, who are working in the epicentre of the crisis in the Liberian capital of Monrovia, are seeing that the viral loads in Ebola patients are much higher than they are used to seeing.

He told Vox.com: 'We are using tests now that weren't using in the past, but there seems to be a belief that the virus load is higher in these patients [today] than what we have seen before. If true, that's a very different bug.

'I have a field team in Monrovia. They are running [tests]. They are telling me that viral loads are coming up very quickly and really high, higher than they are used to seeing.

'It may be that the virus burns hotter and quicker.'

Two-month-old baby Benson, who is feared to be suffering from Ebola. Dr Peter Jahrling believes the virus load in Ebola patients is much higher than they are used to seeing

Jessica Sompon, 17, has her temperature checked after she complained of suffering from a fever. Dr Jahrling believes that the bug causing the current outbreak may burn hotter and faster

Dr Jahrling's warning comes amid calls for the international community to step up their efforts to tackle the Ebola epidemic.

Yesterday the World Health Organisation admitted it blundered in its efforts to halt the outbreak of the virus in Africa, blaming incompetent staff and a lack of information for the failure.

Now British Prime Minister David Cameron has urged the EU to stump up £800millon (1billion euros) to pay for 2,000 health workers to fly out to the affected West African countries, to help stem the spread of the disease.

He has insisted that the UK is 'leading the way' in providing assistance to West Africa as he backed a call by United Nations secretary-general Ban Ki-moon for other countries to deliver more in the way of funding and resources.

Prime Minister David Cameron at the Asia-Europe meeting yesterday urged the EU to put £800million towards trying to stem the spread of Ebola in west Africa

Ebola screening has already begun at Heathrow Airport for passengers coming from West Africa. It has been revealed that checks are also being extended to Manchester and Birmingham airports as well as Gatwick and Eurostar terminals

Mr Cameron, who was in Milan for a meeting of European and Asian nations, said: 'This is the biggest health problem facing our world in a generation. It is very likely to affect a number of the countries here today.

'Britain, in my view, has been leading the way. The action we are taking in Sierra Leone where we are committing well over £100 million, 750 troops, training 800 members of health staff, providing 700 beds - we are doing a huge amount.

'I think it is time for other countries to look at their responsibilities and their resources and act in a similar way to what Britain is doing in Sierra Leone, America is doing in Liberia, France is doing in Guinea.'

Meanwhile, Public Health England (PHE) said screening for travellers arriving in Britain from the affected areas in West Africa is to be introduced at Manchester and Birmingham airports.

Duncan Selbie of PHE said that once the existing measures covering Heathrow, Gatwick and the Eurostar terminal at St Pancras had 'settled', they would be rolled out to other ports of entry.

Passengers were pictured wearing face masks at JFK International airport in New York. Ebola screening is also underway at the airport but American health experts say banning passengers from West Africa would be a bad idea

'Next week the focus will be on Gatwick and St Pancras and, once settled there, we will then move to include Manchester and Birmingham,' he said.

'I appreciate very much that we are taking people away from their normal work, and please be assured that we are thinking hard and listening carefully to those on the ground to see how we can make this more sustainable.

'What I am certain of is that we have the people who know how to keep the country safe and that is exactly what we will do.'

Meanwhile health experts in America have said it would be a bad idea to impose a travel ban on passengers entering the U.S. from West Africa.

The experts' key objection is that a ban could prevent needed medical supplies, food and health care workers from reaching Liberia, Sierra Leone and Guinea, the nations where the epidemic is at its worst.

Without that aid, the deadly virus might spread to wider areas of Africa, making it even more of a threat to the U.S. and the world, experts say.