Waning interest in Ebola could jeopardise efforts to stamp out the world's worst recorded outbreak of the disease, the World Health Organization said on 11 March.

The year-old Ebola outbreak has killed 9,976 people and fears of its spread commanded headlines globally in the second half of last year.

"In terms of the risks, the single biggest one probably at this point is the risk that the world stops looking at this disease, stops looking at these countries," said WHO assistant director general Bruce Aylward.

"It's no longer in the press. It's no longer in front of people and in some ways, these countries are even more isolated right now at a time when they need international assistance more than ever to get the job finished," Aylward told reporters in Geneva.

Case numbers have dwindled to a range of 100-150 for almost the past eight weeks and the disease has been geographically concentrated around Freetown and Conakry, the capitals of Sierra Leone and Guinea respectively.

But the disease is "not waning" and it is much too early to assume the outbreak will end, said Aylward.

"We talk often about how steep the drop in cases has been. The only thing that has dropped more quickly and more steeply has been the new contributions and financing to the programme. David Nabarro, the special envoy of the secretary-general emphasised just yesterday again that $400m [£267m] in new financing is essential by June to keep this programme on track," he said.

Rates of new infections have come down swiftly in recent months, however, and Liberia last week released its last known Ebola patient from hospital.

Sierra Leone remains the country with the highest rate of transmission and, as of 10 March, still had 127 patients in Ebola treatment centres across the country, according to a government health ministry report.

Britain said on Wednesday a military healthcare worker had tested positive for Ebola while working in Sierra Leone and airport officials there said the patient would be flown home overnight.

It was not immediately clear why the patient would not be treated in the British Kerry Town Ebola facility near the capital Freetown which has a special section intended for infected healthcare workers and international staff.