However, the scale of those efforts is far short of what is needed to contain the epidemic.
AIDS has killed more than 25 million people since it was first recognised in 1981, making it one of the most destructive epidemics in history.
An estimated 3.1 million people died from the virus last year and another 4.9 million people became infected, according to this year's AIDS epidemic update report.
For the first time though, there is solid evidence that the increased efforts to combat the disease over the last five years are starting to result in drops in new infections, said UNAIDS chief Peter Piot.
Previously, improvements had been seen in places such as Senegal, Uganda and Thailand, but those were rare exceptions.
"Now we have Kenya, several of the Caribbean countries and Zimbabwe with a decline," Mr Piot said, adding that Zimbabwe is the first place in Southern Africa to show improvement.
"It's in young people. If you see a decrease in prevalence in young people, that reflects a decrease in recent infections."
Sex safer
Sexual behaviour also seems to be getting safer in those areas, Mr Piot said.
"People are starting later with their first sexual intercourse, they are having fewer partners, there's more condom use. It's pretty boring, because you see the same thing over and over, but it's a consistency now that's a really good sign," Mr Piot said.
"I'm actually convinced that there are more countries. We see similar trends in countries in East Africa, but the evidence was not good enough to put in the report," he said.
The most dramatic drops in prevalence have been among pregnant women in urban Kenya, where in some areas the proportion of women infected plummeted from approximately 28 per cent in 1999 to nine per cent in 2003.
Infections in pregnant women are considered a good indicator of what is going on in the rest of the population, experts say.
In the Caribbean, declines are evident in Barbados, the Bahamas and Bermuda, Piot said.
Urban Haiti is showing a drop in the number of people with the virus.
But in that case the figures may be due to more infected people dying rather than fewer becoming infected in the first place, Mr Piot said.
Zimbabwe improves
There have also been improvements in Zimbabwe, where HIV prevalence among pregnant women in the capital Harare has declined from 35 per cent in 1999 to 21 per cent in 2004.
Mr Piot says it marks the second time in more than two decades that a sustained decline in national HIV infection levels has been seen in a sub-Saharan African country.
That country was hit by the virus earlier than others in the region and started intensive programs earlier, he said.
"I absolutely believe we are on a roll," added Dr Jim Kim, HIV chief at the World Health Organisation.
"Everyone is sort of jumping on the bandwagon. I think there's been a fundamental change, even in the past one year, in all the efforts in HIV."
There's a new energy, Mr Kim said, and much of that comes from the recent availability of HIV treatment in the developing world.
About one million HIV patients in the developing world now are on treatment.
That's far short of what is needed, but the availability of drugs has meant that people see a point in getting tested for the virus, which is crucial for prevention efforts.
About 300,000 deaths were avoided last year because of treatment, the report said.
"As much as possible, we've got to get that energy into prevention as well," Mr Kim said.
In 2005, slightly more than A$10.93 billion was spent on tackling HIV in the developing world.
That compares with A$8.2 billion last year, but was still far short of what's needed to get on top of the problem.
UNAIDS estimates that A$12.3 billion will be spent next year, but that $A20.5 billion will be needed.
Epidemics shift
The epidemics continue to intensify in southern Africa.
Growing epidemics are underway in Eastern Europe and in Central and East Asia.
Five years ago, one in 10 new infections were in Asia. Today it is one in four or one in five.
China, Papua New Guinea and Vietnam are facing significant increases.
There are also alarming signs that Pakistan and Indonesia could be on the verge of serious epidemics, the report said.
Across Asia, the epidemics are propelled by combinations of injecting drug use and commercial sex.
Only a handful of countries are making serious enough efforts to introduce programs focusing on these risky behaviours on the scale required, the report warned.
Worldwide, less than one in five people at risk of becoming infected with HIV have access to basic prevention services.
Of people living with HIV only one in ten has been tested and knows that he or she is infected.