By Chris Hogg
BBC News, Tokyo
Asia faces a 150% increase in HIV/Aids infections over the next five years unless more is done, a report warns.
The disease has spread quickly among China's migrant workers
The UNAIDS study says that those most likely to contract HIV - drug users, homosexuals and sex workers - must be the focus of prevention efforts.
The report was published as a conference began in Japan looking at what is needed to try to halt the regional spread of the disease .
In much of Asia people do not think Aids is a big issue, the report said.
It is true that in many countries in this region, the proportion of people infected is low.
In India, for example, less than 1% of the population is infected, much lower than in South Africa, where 20% have HIV.
But because of the large populations of many Asian countries, those figures disguise the huge numbers of infections.
So in India, the number of people with HIV is exactly the same as South Africa, around five million cases.
And in Japan, where the number of infections is relatively small, the disease is spreading as fast as it is in the worst affected countries in the world.
UNAIDS says the priorities in Asia must be cheap medicine and prevention.
As always, the funding available for the fight is inadequate, UNAIDS says.
Asia has a chance to get ahead of this infection; with the right approach, the number of new infections could be halved.