Nearly one in five patients with HIV in Britain may be resistant to at least one life-prolonging drug before they even begin treatment, raising fears that many are having unsafe sex with people already infected and on treatment programmes.
A study by government scientists and clinics over seven years to 2003 suggests an overall figure of 14% resistance, but rates in the final year were 19%. This compares with 7% resistance among chronically infected patients in the US, 6% in France and 10% elsewhere in Europe. Researchers believe the rate is still increasing and say the "epidemic of drug-resistant HIV represents a major clinical and public health problem".
They fear that the trend will limit options for treatment as doctors juggle drugs to find combinations that retain the most potency. The spread of resistance may eventually negate huge reductions in illnesses and deaths brought about by the standard triple therapy of antiretroviral drugs. They have slowed progression of the disease to Aids and death by 86%, recent research has suggested.
People are usually given a drug from each of three classes, which tackle the virus in different ways. Patients are often diagnosed long after they become infected and many do not start treatment for some time because they feel well.
The new data, published in the British Medical Journal's Online First, reports on tests of 2,357 people. Of these 335 showed some resistance, 257 to drugs in one class only, 44 to drugs in two classes and 34 in all three. In the early years the resistance rate was about 10% but it climbed later. Most of those in the study were men probably infected through sex with other men, but rates of resistance were higher in those infected through heterosexual sex. The 22% drug resistance rate among patients with recent HIV infection was higher than the 14% among those presumed to have been infected some time before.
Dr Deenan Pillay, of the Health Protection Agency's centre of infections, said it could be inferred that people in the study had been infected by someone who was already on treatment and knew they had the virus."For some reason among that group within the UK there is normally a lot of unsafe sex going on."
