The UK is providing money to help two species of vulture in south Asia whose rapid decline has alarmed conservationists.

In some areas numbers have fallen by over 90% in under 10 years. Birds in Pakistan and Nepal are increasingly affected, and scientists fear others in Europe and Africa could also succumb.

And there is growing concern over the implications for human health.

Under the Darwin Initiative for the Survival of Species, the UK Government will pay �148,000 over three years to try to find what is affecting the two species, the white-backed and long-billed vultures.

The initiative seeks to safeguard the world's biodiversity by drawing on British expertise to help countries rich in biodiversity, but poor financially.

British organisations

Three British organisations and one in India will work together to spend the money.

It is getting progressively worse. There is no apparent recovery, and the problem is spreading Dr Debbie Pain RSPB

They are the Royal Society for the Protection of Birds (RSPB), the Institute of Zoology, the National Birds of Prey Centre, and Bombay Natural History Society (BNHS).

Scientists are almost certain the vultures are being affected by an unidentified viral disease, and the money will pay for three people to work at a permanent unit in India trying to pinpoint the disease's cause.

It will also fund monitoring in the wild and the establishment of a captive care centre.

This will allow scientists to study the disease and possible ways of helping the vultures to recover. It will also train workers who may be able to set up a captive breeding programme.

Characteristic sign

The RSPB's head of international research, Dr Debbie Pain, told BBC News Online: "The characteristic sign of an affected bird is one whose head is hanging almost down to its feet for long periods.

We've just heard from western Rajasthan, where there's a big dump that receives an average of 20 carcasses daily Dr Debbie Pain RSPB

"It's a syndrome that seems to be associated with this disease and we are 98% certain it is a disease that is killing the vultures, because other possible causes, like pesticides, are much more localised in their effects.

"We've just heard from western Rajasthan, where there's a big dump that receives an average of 20 animal carcasses daily.

"There are now large numbers of Eurasian and Himalayan griffin vultures there, and we think they've moved in because the white-backed and long-billed vultures have all died."

Worsening situation

An India-wide survey last year by the BNHS found that the two affected species had declined by 90% since the last survey in 1992/93, and that in many places they had disappeared altogether.

Most sick birds become lethargic and usually die within about a month of symptoms developing.

The BNHS said that some vultures in Pakistan and Nepal were also being affected, but the situation in all three countries appears to have deteriorated since then.

Dr Pain said: "It is getting progressively worse. There is no apparent recovery, and the problem is spreading.

"The number of sick birds in Pakistan and Nepal is highest close to the Indian frontier.

'Moving eastwards

"It looks as if it is moving westwards, and that it might reach Europe and even Africa.

Where you used to see tens of thousands of vultures at a carcase dump, now you might see half-a-dozen. Dr Andrew Cunningham, Institute of Zoology

"It affects vultures from the Gyps genus, and there are species of Gyps vultures in France, Spain, and contiguous populations all the way down to South Africa.

"And what's happening is not just a conservation problem. It has implications for human health too.

"The Parsees dispose of their dead by putting the bodies out on 'towers of silence' for the vultures to eat, so as to avoid polluting earth or water.

"So they face a major problem. At the carcass dump in Rajasthan there are now more than a 1,000 feral dogs where there used to be vultures. So there is a growing threat from rabies and other diseases."

Monitored sites

Dr Andrew Cunningham, of the Institute of Zoology, has just returned from India.

He told BBC News Online: "It's a huge problem. The feral dog population is exploding, and people are now having to protect themselves with sticks.

"The disease is worse than it was six months ago: at some of the nesting sites being monitored, there aren't any nests.

"Where you used to see tens of thousands of vultures at a carcass dump, now you might see half-a-dozen.

"They're all dying of enteritis and visceral gout, when their uric acid crystallises out into all the internal organs. That finally does them in.

"It's got to be an infectious agent: it's so selective, attacking the Gyps birds. Four of the eight vulture species found in India are apparently unaffected.

"It's a mystery, but slow progress is being made in India, and the Darwin Initiative grant should help immensely."