The BBC's Andrew Burroughs on the impact of AIDS drugs

Tens of thousands of people have found that the virus is resisting the new drugs. In the USA, researchers estimate that the virus has become resistant to around 50% of the new drugs.

In the UK, the figure is not as high, but there is concern that the gains may be being turned back. Resistance was first noticed to AZT, the main drug associated with AIDS.

Resistance has also been noted even when the drug is used in combination with other strong treatments.

Not a cure

Combination therapy is not a cure for AIDS, but it has reduced HIV - the virus which causes AIDS - to almost non-existant levels in many patients.

Gus Cairns faces an uncertain future

However, it does not work for everyone and those for whom it does work are forced to follow a strict regime, which involves taking the drugs several times a day. The drugs also have side effects.

But when it does work, combination therapy has brought big changes.

People who were given months to live have found that the disease has been brought under control and they can even return to work.

Journalist Gus Cairns was told he had only three months to live. He planned his own funeral and had even written his own obituary.

Then along came combination therapy and his health has improved to such an extent that he can now return to work full-time.

But he says the new lease of life has brought uncertainty. "I do not know whether the drugs will carry on working or will stop working. I really do not know what the future holds," he said.

Cutbacks

Nevertheless, health authorities and councils around Britain have been cutting back on services while money has been poured into funding the new drugs, which cost around £10,000 a patient per year.

An All-Party Parliamentary Group is looking into the future of AIDS treatment

The London Lighthouse, one of the best known centres for people with HIV and AIDS, is facing closure because the local authority has withdrawn funding.

Other AIDS charities have been adapting to the new funding climate by merging some of their services.

People with AIDS are also having some of their disability grants cut. Kensington and Chelsea council, for example, recently reviewed travel grants for people with AIDS.

They tested people on grants on their ability to walk to the nearest bus stop or underground station. Many lost their right to subsidised travel as a result.