About 3 million people worldwide had received the drug cocktails by the end of 2007, far short of the estimated 6.7 million infected people still in need of treatment, the researchers added.

There are, of course, drawbacks which the researchers and other scientists pointed out. One is how health systems in poor countries can cope with widespread testing, and whether people can stick to the drugs they must take for life.

"At its best, the strategy would prevent morbidity and mortality for the population, both through better treatment of the individual and reduced spread of HIV," Geoffrey Garnett, a researcher at Imperial College London, wrote in a commentary in The Lancet.

"At its worst, the strategy will involve over-testing, over-treatment, side effects, resistance, and potentially reduced autonomy of the individual in their choices of care."