Working at breakneck speed, the nurses rush between departments at Guinea's largest hospital, wearing gloves they have bought at their own expense to protect themselves against the Ebola virus.

The often chronically under-resourced staff of Donka hospital in the capital Conakry -- like health workers across west Africa -- sacrifice everything in the battle against a deadly epidemic, often their own lives.

The World Health Organization said last week that more than 120 health workers across the region had died during the "unprecedented" outbreak which began early this year, and more than 240 had been infected.

"The outbreak of Ebola virus disease in west Africa is unprecedented in many ways, including the high proportion of doctors, nurses, and other healthcare workers who have been infected," the agency said in a statement.

The toll on health workers is all the more the more devastating in the three worst-hit nations -- Guinea, Liberia and Sierra Leone -- where more than 1,500 people have died and where there are just one or two doctors for every 100,000 people.

Sierra Leone, which had already lost its only virologist and other senior medics, reported the death of a third physician last week.

A Senegalese WHO expert was also infected in Sierra Leone and was admitted on Wednesday to a hospital in the German city of Hamburg.

- 'If God lets me live' -

"One day, if God lets me live, when Ebola becomes a distant memory, I will explain to my grandchildren or great-grandchildren that this disease called Ebola shook the world in 2014," says Marie Fikhe, a nurse in charge of a department at Donka hospital.

She is interrupted by ambulance sirens announcing the admission of a new case of Ebola, a fever which has killed more than half the people it has infected in the west African outbreak and is passed on via contact with bodily fluids.

"After every task, you have to change gloves and wash your hands, yet we are only given one pack a week, which is clearly insufficient," says Fikhe.

"Everybody knows that sponsors donate loads of them, so they should be used to treat patients... (yet) very often, after a few days, they can be found being sold on the local market."

She recalls a colleague who died in the hospital's isolation centre because she had unwittingly contracted Ebola while nursing a woman everyone assumed had typhoid.

"It was right at the beginning, before the laboratory in Lyon discovered that the disease raging in the south was Ebola virus disease," Fikhe says.

- Honour and responsibility -

Among the reasons for the heavy price paid by the medical profession, WHO cites the similarity between the early symptoms of Ebola and those of several infectious diseases endemic to the region, such as malaria, typhoid fever and Lassa fever.

The agency also blames a "lack or misuse of personal protective equipment and the small numbers of medical personnel".

In Donka hospital, a nurse who asks to be identified as "Dr Mara" underlines the problem.

"Look at my outfit. I had to buy it at my own expense... Mostly, I'll source decent white fabrics from the market and get them sewn by my tailor."

"Even the gloves on the table there, it was me who bought them," insists the nurse, in between dashes to casualty, the pharmacy, the laboratory and the Ebola isolation unit, claiming to have to work without surgical spirit, soap or even water.

One of her colleagues, Jacqueline Thea, a frail figure in overalls which are too big, says she remains in the job "because I do not want to escape my responsibilities, because I was sworn in, because I want to honour my children".

"Otherwise I would have given up everything to go far away from here, away from Guinea," she says.