Some 25 million people across the globe have died in the quarter-century after the first documented cases, but Peter Piot of UNAIDS predicts a further globalization of the epidemic spreading to every corner of the world.
Among the areas where the disease is now spreading very fast are Russia, Ukraine, and Central Asia.
In an interview with RFE/RL, Piot said the Ukrainian and Russian governments have made progress in slowing the spread of the virus in their countries. But he says the two nations remain on the verge of a major AIDS pandemic that could hit the youngest members of their populations.
Piot described the response of these two countries -- and of post-Soviet states in Central Asia -- as "totally inadequate and insufficient."
However, he said that he now sees "very, very hope-giving signs in major increases in budget -- 10 to 12 times in Russia, also in Ukraine -- and more action on the ground."
The head of UNAIDS says the spread of HIV among injecting drug users is a fundamental issue that continues not to be addressed in the region.