The discovery, made last month, that a criminal posing as a medical doctor had run a thriving organ racket for nearly a decade horrified India and the world.

From his base in Gurgaon, a booming satellite city on the edge of Delhi, Amit Kumar - or 'Doctor Kidney' as Indian newspapers have dubbed him - is alleged to have paid or forced hundreds of poor labourers to donate their kidneys to wealthy donors.

Qualified as a practitioner of ayurveda - a traditional Indian medical practice that holds, among other things, that the tastes of foods and herbs have specific physiological effects - Mr Kumar was no doctor at all. 'He wasn't even qualified to write a prescription,' says Dr Narender Saini, honorary assistant of the Indian Medical Association. 'It's most irresponsible for the media to go on calling him a doctor when he was nothing of the sort.'

Indeed, argues Dr Saini, Mr Kumar's activities should have come as less of a shock in India. Though the country banned the trade in human organs in 1994, it has done little to crack down on quackery, as the practice of working unauthorised as a doctor is known here.

And yet, the work of quacks constitutes 'an unacceptable level of health care that is quite incredibly dangerous', according to Dr Sandeep Guleria, professor of medicine at Delhi's All India Institute of Medical Sciences, the country's biggest teaching hospital.

There are no estimates of the total number of quacks operating in India, but in Delhi alone, it is estimated there are some 40,000. Most operate in the teeming slums, in which up to a third of the capital's population of 14 million-plus live.

In any Delhi slum, inquiries for 'a doctor' will lead to one of many hole-in-the-wall clinic-shacks.

Some have red medical crosses painted on the door; others, like Mr Noor's, have no sign, but are well known by local people. During opening hours, long queues of skinny, barefoot patients often wait outside. Few leave without medicine of some sort.

Manoj's 'doctor', Noor Muhammed, a smartly dressed thirtysomething, sees up to 40 patients a day in a slum in central Delhi. After the most cursory of examinations - consisting of blood pressure and temperature checks - the kindly mannered man dispenses and prescribes medicines from antibiotics to injections for viral fever.

'The most common ailments here are dysentery and fever,' Mr Noor says, as he hands a bottle of cough mixture to the mother of two tiny children with heavy coughs.

The neighbourhood in which he operates is a typical Indian slum. Houses are one- or two-room shacks of corrugated iron, plywood and tarpaulin. Half-naked children play by open sewers. Stray dogs sniff through piles of stinking rubbish. Flies hover as women prepare food on the dirty pavement.

Bhagwan Deyi, a grandmother who says she's 'about 50' but looks much older, has only ever consulted 'Jhola chaaps' (a Hindu term meaning shoulder bag - or itinerant - medicine salesman) when she's been sick.

The tablets they have sold her have done nothing for the 10-year pain in her leg and hip, she adds with a grimace.

Doctors in government hospitals regularly see the effects of quacks' work.

'They take acute patients and make them chronic,' says Dr K.K. Kohli, chairman of the anti-quackery committee of the Delhi Medical Council, which regulates the work of doctors in the city.

Quacks' blunders range from misdiagnoses to the prescription of steroids as pick-me-ups and the sale of homemade remedies and cheap, expired antibiotics.

Their enthusiasm for antibiotics is a major cause of high levels of drug resistance in India, Dr Guleria says. Sometimes, their work is fatal. An ayurvedic practitioner was reported to have killed a small baby in Delhi on February 19 by trying to perform tongue surgery for which he was not qualified. The baby bled to death.

Last year, concerned by the preponderance of advertisements that promised miracle cures for everything from hair loss to HIV, Delhi's state government extended the power of the Drugs and Magic Remedies (Objectionable Advertisement) Act, 1954 to cover all forms of media, including television. Previously, it had covered only print.

But Dr Kohli says more powerful laws are required to curb the quacks. A decade ago, Delhi drafted an anti-quackery bill, directly outlawing the practice, but the bill quickly disappeared from sight.

In the wake of the Gurgaon kidney scandal, Dr Kohli is urging the government to make the bill law.

But the government is unlikely to do so any time soon. This is largely because in too many areas of India, if you are poor and sick, you either see a quack or you don't see anyone.

While India's private health sector booms, and 'five star' hospitals import flashy technology from overseas to serve a growing middle class and an increasing number of 'medical tourists', the government-funded health system remains skeletal. There are only 60 doctors for every 100,000 people, compared with 257 per 100,000 in the United States, and government spending on health is pitifully low.

'Health is simply not a priority sector in India,' Dr Kohli says.

'There is no political will to improve people's access to health care, even though this will at some point start to take its toll on the economy.'

Though the insurance sector was opened up to private domestic and foreign companies in 2000, health insurance remains beyond the reach of most Indians. Government-run clinics are too far away and the queues too long. In many rural areas, the clinics don't exist.

And private doctors, even those who charge only 100 rupees (HK$19.50) a consultation - many doctors in Delhi charge three times this - are unaffordable for many.

Quacks typically ask for between five and 20 rupees per consultation.

For Subosh, an impeccably mannered ragpicker who goes by one name, this does not even constitute a choice.

Earning about 50 rupees a day for sorting through piles of rubbish for anything of recyclable value, Mr Subosh says even the price of a quack and the medicines they prescribe can be crippling when any of his three children are sick.

'Medicine is very expensive but if your children are sick you have to buy it, of course,' he says.

Across the way, Govind Ram, who irons clothes for a living, is luckier. He can afford to go to a qualified doctor. 'He's a lot more expensive, around 150 rupees, but it is better,' says the white-haired 55-year-old, sitting cross-legged beside his ironing table.

'I don't think the tablets the jhola chaaps give out work. But it's all most people can afford.'

So, until India improves its health care provision, the poorest people will continue to rely on quacks.

Despite the problems they cause, it is also undoubtedly true that the antibiotics they prescribe and dispense may have saved many lives.

Indeed, so deeply embedded are fake doctors in the creaking health system that the National Aids Control Organisation has said it plans to include them in its Aids control programme. Naco will train a select number of quacks in basic care and counselling of people with sexually transmitted diseases, mindful of the role these can play in the spread of HIV infection.

Back in his clinic, Mr Noor says many quacks are perfectly responsible.

As evidence of this, he cites the fact that he refers all 'serious cases' to government hospitals. When asked how he diagnoses these serious cases, he shrugs.