The California researchers subjected 141 newly-diagnosed patients to genetic testing. More than a quarter of strains studied were between two and a half and 10 times more resistant to one or more drugs. The researchers call for greater monitoring of the phenomenon. In an accompanying editorial, Dr Roger Pomerantz of Jefferson Medical College in Philadelphia says the results may warrant genetic testing of anyone found to be resistant to anti-retroviral drugs. Genetic testing costs thousands of dollars, but he said that, with time, cheaper and simpler tests would be developed.
Doctors believe immediate action is needed to tackle drug-resistant strains to prevent their spread.
Dr Pomerantz added that safer sex messages also needed to be emphasised. Aids experts say drug resistance has been noted in the UK, but monitoring is not as good as in other Western countries. They also called for greater efforts to develop new drugs to fight HIV so that the medical world can keep ahead of the virus. Mandela takes on Mbeki Row over Aids vaccine Links to top Aids stories are at the foot of the page.