The problem is worse in developing countries but the organisation says more effective prevention could halve the total of new infections this decade.
In a keynote speech to open the WHO Aids conference in Berlin today, Dr Michael Merson, director of its global programme on Aids, will chart the 'relentless advance of HIV'. Overall the total of known Aids cases stands at 2.5 million - 20 per cent higher than last year.
The WHO, in figures released today, estimates that 13 million people have been infected since the start of the pandemic in 1983. About half of infections have been in people aged 15-24. Three- quarters of infections were transmitted by unprotected sexual intercourse.
Dr Merson condemns the 'denial and complacency' surrounding Aids. He says in his speech: 'Africa staggers under the burden of Aids, and yet we hear the media claim that the African pandemic is a myth . . . denying the African pandemic is an outrage; it is an insult to the memory of the millions who died. 'Another form of denial is the so- called lifestyle theory of Aids. They were disproved years ago, but some individuals still confuse our youth by telling them that HIV is not the cause of Aids. And in one of the strangest denial theories ever to raise its head, heterosexuals in some countries are now claiming that they are not at any risk of HIV . . . if this is not magic thinking, what is?'
The largest number of infections is in sub-Saharan Africa - more than 8 million - but the biggest rise is in Latin and South America, and South-east Asia.
In Europe needle-sharing accounts for almost a third of recent Aids cases, 50 per cent more than in the mid-80s. Heterosexual transmission is rising, particularly in urban populations with high rates of sexually transmitted diseases or drug injecting. 'Up to a third of newly infected people in some cities in Scotland have acquired HIV from heterosexual intercourse,' Dr Merson says.
Despite millions of pounds invested in research and prevention, the global response is 'inadequate and unrealistic'. Effective condom distribution and education could halve the total of new infections. 'This would mean over 4 million fewer infections in Africa, over 4 million fewer in Asia and a reduction of about 1 million infections in Latin America.'
WHO puts the cost at about dollars 2.5bn ( pounds 1.6bn) - 'a fraction of the cost of Operation Desert Storm, and it would hardly buy one can of coke for every person in the world'. He called on scientists to refocus research, to speed up development of a vaccine and investigate new drugs. A vaginal microbicide could revolutionise Aids prevention.
More than 15,000 delegates from 166 countries are at this week's conference.Reuse content