HIV has proved adept at foiling drugs
There have been significant gains in preventing new HIV infections in a number of heavily-affected countries, a United Nations programme report says.
However, UNAids warns the Aids epidemic is not over in any part of the world.
The report says prevention programmes have seen changes in sexual behaviour, and a drop in infection rates in countries such as Rwanda and Zimbabwe.
Condom use is also increasing among young people with multiple partners in many countries.
HIV INFECTIONS 2007
Sub-Saharan Africa: Total infections: 22m New infections: 1.9m Deaths: 1.5m
South and Southeast Asia: Total infections: 4.2m New infections: 330,000 Deaths: 340,000
Latin America: Total infections: 1.7m New infections: 140,000 Deaths: 63,000
Eastern Europe and Central Asia: Total infections:1.5m New infections: 110,000 Deaths: 58,000
North America: Total infections: 1.2m New infections: 54,000 Deaths: 23,000
East Asia: Total infections: 740,000 New infections: 52,000 Deaths: 40,000
Western and Central Europe: Total infections: 730,000 New infections: 27,000 Deaths: 8,000
North Africa and Middle East: Total infections: 380,000 New infections: 40,000 Deaths: 27,000
Caribbean: Total infections: 230,000 New infections: 20,000 Deaths: 14,000
Oceania: Total infections: 74,000 New infections: 13,000 Deaths: 1,000
This has been seen in seven of the most affected countries: Burkina Faso, Cameroon, Ethiopia, Ghana, Malawi, Uganda and Zambia.
In Cameroon the percentage of young people having sex before the age of 15 has decreased from 35% to 14%.
UNAids reports that since 2005 there has been a tripling of HIV prevention efforts, with a focus on sex workers, men who have sex with men, and injecting drug users.
The report also reveals that the percentage of HIV-positive pregnant women receiving antiretroviral drugs to prevent transmission of the virus to their child rose from 14% in 2005 to 33% in 2007.
In the same period the numbers of new infections among children fell from 410,000 to 370,000.
Dr Peter Piot, UNAIDS executive director, welcomed the progress.
But he said: "Gains in saving lives by preventing new infections and providing treatment to people living with HIV must be sustained over the long term.
"Short-term gains should serve as a platform for reinvigorating combination HIV prevention and treatment efforts and not spur complacency."
Globally, the number of new HIV infections has declined from 3 million in 2001 to 2.7 million in 2007. However, rates of infection are rising in many countries.
The BBC's Peter Biles reports from an HIV care centre in Johannesburg
There are now an estimated 33 million people living with HIV worldwide, with two million estimated to have died from Aids last year.
RISING RATES OF HIV
Papua New Guinea
The number of deaths was down for the second consecutive year - 200,000 less than the 2005 figure.
Aids continues to be the leading cause of death in Africa, which accounts for 67% of the total number of people living with HIV.
Six out of ten of those living with HIV in Africa are women.
The UNAids report stresses that the fight against HIV requires sustained long-term financing.
It warns that as more people go on treatment and live longer, budgets for HIV will have to increase over the next few decades.