But the seeds were planted about a decade earlier when Thailand made AIDS prevention a top priority. It introduced initiatives such as the 100-percent Condom Program, which promoted usage among sex workers.

This and other programs, combined with a wide network of district level hospitals and rural health clinics, have enabled it to control infection levels and allowed it to implement the NAPHA program, the bank said.

Without the prevention campaigns, Thailand would have had 7.7 million HIV cases and 850,000 AIDS cases in 2005, about 14 times more than today, the bank estimated in a report during the 16th International AIDS conference in Toronto.

"What we figured is that for every dollar they spent on prevention, they saved about $43 in treatment costs. That makes a benefit-cost ratio of 43-to-1, which is unheard of," Mead Over, a World Bank economist and co-author of the report, told Reuters.

The bank estimates Thailand has avoided the need to spend an extra $18.6 billion on treatment over the decade through 2012.

It says countries such as China and India, where the epidemic is at an earlier stage, could take lessons from the Thai programs.

"Thailand's past success with prevention is the most important reason the country can afford universal access to (AIDS treatments) today. Furthermore it is an essential condition of its continued ability to afford treatment in the future," said Over.

UP TO 6 MILLION COULD BENEFIT

Under the NAPHA program, a patient can walk into a hospital or rural clinic and pay 30 baht (80 U.S. cents) for treatment.

In the report, the bank says that 5 million or 6 million people worldwide could immediately benefit from similar treatment, but only 700,000 are receiving the therapy.

However, the bank warns that Thailand's costs will rise as an increasing number of surviving patients -- the bank estimates 572,500 Thais were living with HIV/AIDS in 2004 -- turn to so-called second-line drugs, which are seven to 28 times more expensive than those given as the first course of treatment.

Many of these drugs are patented and sold by large pharmaceutical firms. This means Thailand will have to decide whether to pay their prices, negotiate more favorable terms or exercise its rights under World Trade Organization rules to issue compulsory licenses, which allow other makers to produce a patented drug without permission from a foreign patent owner.

The bank says by exercising compulsory licensing, Thailand could save about $3.2 billion in health costs through 2015.

But by doing so, the government would run afoul of U.S. policy, which is a serious concern, Over said, noting that $3.2 billion represents just a fraction of the value of Thai exports to the United States in the past year.

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