Paris (AFP) - For nearly four decades, mention of the Ebola virus has evoked death and terror, yet a simple factor -- money -- has stood in the way of erasing the curse, experts say.

Despite its evil reputation, Ebola breaks out only rarely in brief if murderous spurts in impoverished African countries.

That tiny -- and poor -- market means the disease has been a very low priority for Big Pharma, given the hundreds of millions of dollars it can take to devise a new drug or vaccine.

Today, after years of low-key progress with the Pentagon as main funder, the search for vaccines and drugs for Ebola has been thrown into higher gear and, for now, the profit factor has been put to one side.

"Until this west African epidemic, Ebola was not a public health problem and (was) a really rare disease," says Professor Peter Piot, director of the London School of Hygiene and Tropical Medicine, who co-discovered the Ebola virus in 1976.

"There was very little interest in all quarters, not just pharma," Piot said in an email to AFP.

"Things have changed now, and two major companies are investing in a vaccine -- GSK (GlaxoSmithKline) and (Johnson & Johnson subsidiary) Janssen."

- Deaths in Africa -

Sylvain Baize, in charge of the Viral Haemorrhagic Fevers Reference Centre at France's Pasteur Institute, said Ebola had claimed fewer than 2,000 lives in almost 40 years, a minute toll compared with other diseases.

"If these 2,000 deaths had occurred in industrialised countries, things may have been different, but it was 2,000 dead in the middle of Africa, so nobody cared very much," Baize said sardonically.

Ebola's extraordinary lethality was another reason why it never became a top target for research, he said.

"It has to be confined in a top-security P4 laboratory, of which there are very few in the world, so there are not many people who in fact can work on it," Baize said.

The recent shakeup has been spurred by an epidemic in four west African countries -- Guinea, Liberia, Nigeria and Sierra Leone -- that has killed more than 2,400 people, about half of the confirmed infections.

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The outbreak has caused social dislocation and economic disruption, and bred fears in neighbouring countries and Europe that the deathly disease could spread there too.

The two treatments and two vaccines furthest advanced in the research pipeline are still at the very earliest testing stages to see if they are safe -- and if they work.

On August 12, the UN's World Health Organisation (WHO) gave the green light to using experimental drugs, saying it would be ethical given the extent of the Ebola crisis and the fact that no cure or vaccine so far exists.

Human trials typically take several years under an exhaustive, three-phase vetting procedure.

On September 5, the WHO voiced hopes a vaccine would be available in November for frontline health workers.

If this fast-tracking process yields results, it raises the next question: Who will pay to manufacture the drug and distribute it?

"Ebola is a classic orphan disease," said Annette Rid, a doctor of bioethics at King's College London, adding that public funds, charities and institutional donors would have to stump up the seed money.

"Once it is established that a therapy or vaccine is effective, stockpiles need to be established in those African countries where Ebola is likely to re-emerge," said Piot.

"This can be funded by the international community, and done under the aegis of the WHO."

Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases (NIAID), said he was increasingly optimistic that Big Pharma would play a role, given the scale of the crisis.

"I think there was previously no incentive, but now that everyone sees that it is a big problem, we are getting more and more companies involved," he told AFP.

- Carrots for Pharma -

Seth Berkley, head of the GAVI Alliance, a public-private partnership designed to bring vaccines to poor countries, said a panoply of tools existed for harnessing the profit motive.

"You can directly finance the vaccine technology transfer, you can incentivise companies by funding them directly, you can create an advanced market commitment with supplemental funds to try to make it a good deal for business, you can create a long-term plan for buying the vaccines as an incentive," he said.

"There is a range of mechanisms there and it could be done rather quickly."