Ebola treatment facilities in Monrovia, the Liberian capital, are now so overwhelmed they are turning away up to 30 infected people every day according the medical charity Medecins sans Frontieres.

Given the rate at which the virus is spreading, it says the virus will soon be having an “apocalyptic” impact on the country and its neighbours unless there is a dramatic increase in international assistance.

“It could get very bad indeed,” said Prof John Edmunds, an epidemiologist at the London School of Hygiene and Tropical Medicine. “And I mean you can’t rule out some sort of nightmare doomsday scenario.”

“But the quicker we react and put interventions in place, the better chance we’ve got of avoiding something really, really serious.”

The leading epidemiologist is studying the spread of the virus in Monrovia, where the outbreak is now most intense. He has told Channel 4 News that based on the current rate of spread and lack of power to control it, it has the potential to infect the majority of the population of the country.

Getting a real handle on how fast the virus us spreading is becoming impossible. Official statistics are largely based on admissions and deaths in Ebola treatment facilities, from which people are now being turned away.

But based on data from recent weeks, researchers estimate each case in the community could be giving rise to about 1.5 more cases. “That means each case that is turned away generates more than one new case,” said Edmunds. And then you’re looking at an ongoing epidemic that could permeate right through society unless we do something to stop it right now.”

“The doubling time of this epidemic is about two weeks, so if we are overwhelmed with our resources right now, it’s going to be twice as bad in two weeks’ time.”

Last night the Bill and Melinda Gates Foundation pledged $50m to support the emergency response to Ebola. In recent days the US government has committed an additional $185m towards equipment and 100 medical personnel.

The British government also announced this week that it would build a 62-bed field hospital to help with the outbreak in Sierra Leone. The US says its commitment has added an additional 1,000 beds. However the World Health Organisation has estimated an additional 1,000 Ebola treatment beds are needed in Monrovia alone.

Follow @TomClarkeC4 on Twitter