'The WHO's criteria for elimination is as a public health problem rather than total eradication in the way smallpox has disappeared,' Mr Soutar said. Lepra fears funds will dry up and the disease will slip from the world's radar if too much is made of reaching the UN's targets. Government interest could wane.

'We don't want to see the WHO announcing in 20 years' time that leprosy is a re-emerging disease,' Mr Soutar said.

Dr D. C. Agrawal, general secretary of the Indian Leprosy Association, is also worried about complacency. 'Unless we develop a vaccine and defeat the ignorance attached to the disease it will never be totally eradicated.'

All agree, however, that remarkable progress has been achieved.

India may still have three times as many leprosy patients as the next most affected country, Brazil, and be home to more than half of the world's sufferers, but the shadow cast by a uniquely cruel disease is at last lifting in what many consider to be its home.

Indian writings from 600BC describe a disease that most experts agree was leprosy. It doesn't appear in the records of ancient Greece until the army of Alexander the Great came back from India in 326BC. In Rome, the first mention coincides with the return of Pompey's troops from Asia Minor in 62BC. Roman soldiers took the disease into northern Europe, where it infected possibly a quarter of the population.

The Black Death killed hundreds of thousands of people already weakened by leprosy.

The shame attached to those suffering from the disease is legendary. Even the New Testament sets lepers apart: Jesus healed the blind and deaf, but cleansed the lepers, implying a moral stigma.

By the Middle Ages, European religious leaders were condemning lepers as sinners burning with carnal desire and intent on evil.

In India, the stigma and myth live on, with many regarding it as a highly contagious and incurable affliction. Leprosy sufferers and their families are ostracised, banned from temples and pushed out of their homes and on to the streets of big cities, where they have to beg for a living, their wounds considered divine retribution for sins committed in this or a past life.

In fact, a far more humble agent, Mycobacterium leprae - a rod-shaped bacterium similar to that which causes tuberculosis - is to blame. It attacks the skin, nerves, respiratory system and eyes, and can spread to internal organs if not treated. Hair loss is common. Left untreated, wounds fester, and hands and feet swell and are left deformed. The disease spreads only after close and prolonged contact with people infected with M. leprae.

When Norwegian scientist Dr Armauer Hansen discovered M. leprae in 1873 (leprosy is also known as Hansen's disease), it was the first bacterium to be identified as causing disease in man. An effective treatment, however, appeared only in the late 1940s, with the introduction of the drug dapsone.

Leprosy bacilli resistant to dapsone gradually appeared from the 1960s and became widespread, reducing hopes of a total defeat for the disease.

In 1981, the outlook brightened as scientists came up with a multi-drug therapy that combined dapsone with two other compounds, rifampicin and clofazimine. The success was stunning. The new approach slashed treatment times from years to months, and was so safe it could be given to pregnant women. Patients lost their infectiousness within a month.

The disease was soon in rapid retreat across much of the world. Vietnam, which had communities where the infection rate was a staggering 30 per cent, Thailand, and Sri Lanka reached the WHO's elimination target in 1995. Outside Asia, badly affected Venezuela followed suit.

Last year, the number of new cases detected in all these previously endemic countries was in the hundreds rather than thousands.

The multiple drug treatment is credited with curing 12 million people and reducing the leprosy burden by 87 per cent. Relapse is rare. In the late 90s, India launched a major campaign to increase awareness, break down the pariah status the disease carried, and get people to come forward and be treated. Local health staff were retrained and told to be more pro-active, and from January 2000, TV, radio, cinemas, buses and rickshaws carried the anti-leprosy, anti-discrimination message. In one state, house-to-house examination reached 29 million people. The WHO provided drugs free of charge.

Simple procedures such as testing areas of suspected infection for sensory loss - one of the earliest symptoms - have revolutionised detection for isolated villagers.

'The big change came with the integration of leprosy treatments into the general health care system in India,' said Serge Manoncourt, a Delhi-based WHO official. 'The stigma has been reduced. More people now understand that leprosy is a disease like many others, and that it's treatable.'

'A lot more needs to be done to rehabilitate sufferers. India must continue to chip away at still deeply entrenched ignorance and prejudice,' said Dr Agrawal. 'It will be at least a generation before society stops victimising leprosy sufferers.'