Alarm at spread of drug-resistant Aids

More than three-quarters of US patients with the Aids virus may be developing resistance to one or more of their drugs within three years of starting treatment, new research says.

The revelation that drug-resistant HIV is spreading even faster than was feared reinforces concern about the waning usefulness of treatments that have helped many patients lead normal lives.

Better drugs, a vaccine to control the virus, and more widespread testing of patients to see if they have been infected with a resistant form of HIV are all urgently needed, scientists believe.

Douglas Richman, of the Veteran's Administration hospital and University of California, San Diego, told a Chicago conference on Tuesday how his research team had extrapolated figures obtained from blood tests on 1,647 patients conducted in 1999, three years after they entered medical care.

The results suggested that 78% carried a virus which was resistant to at least one drug in the cocktail of medicines they took, and half were resistant to more than one class of drug. There are about 15 drugs in four classes, and most patients are on a three-drug regime.

Dr Richman said doctors would have to start testing patients right away to check for resistance.

"We have to use drugs more intelligently," he said. "We have to try to figure out ways to prevent transmission and we have to find drugs that work against resistant virus."

Researchers in Britain suggested that more than a quarter of patients newly infected last year may have virus resistant to at least one drug.