But experts say a focus on treatment led to prevention campaigns being scaled back just as transmission modes began to change in Thailand.
Now young people are the largest component of new HIV infections and too many feel the disease is no threat to them.
"I thought I had done my job and I became an ordinary citizen, but nobody continued the momentum as strong as I had hoped," Mechai said.
Thailand, like most countries, faces an uphill battle against the stigma attached to the disease. Last month, a Bangkok hotel made headlines after it segregated HIV-positive guests.
"This is a clear indication that if you stop public education or reduce it too rapidly, ignorance comes to the fore," said Mechai, who fired off letters to hotels warning of boycotts if they discriminated against conference delegates.
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