The Ebola outbreak in West Africa is accelerating, and is "completely out of control," according to a US National Institute of Health official.

Anthony Fauci, director of NIH's National Institute of Allergy and Infectious Diseases, told Newsweek that 42% of the total reported cases occurred in the last month, indicating an exponential rate of infection in Africa.

This meant the virus is beyond the interventions in place.

He stressed on the need for better health care infrastructure and personal protective medical gear for which there will need to be a "sea change" in the amount of assistance being sent to aid groups.

Fauci's view had been mirrored by Thomas Kenyon, director of the Centers of Disease Control and Prevention's Center for Global Health, who told Reuters that the outbreak, which had been partially under control, is "back on the increase now".

This week the UN has announced further funds totalling $600 million to check the outbreak.

As of August 31, Guinea, Liberia and Sierra Leone had reported 1,841 confirmed, suspected, and probable deaths from Ebola, according to the World Health Organisation. Nigeria has reported seven deaths. There has also been one confirmed case in Senegal (though no recorded casualties).

Meanwhile, an American doctor Dr Rick Sacra, 51, who was infected with Ebola while working in Liberia, is being flown to a Nebraska hospital for treatment.