HIV/AIDS is a relatively recent but growing problem in many parts of Asia. With 60% of the world’s population and widespread evidence of behaviour and situations that expose people to HIV, there is no room for complacency.

• In comparison with the rates of HIV infection in Africa, those in the general population of Asia are still low. The prevalence among 15-49-year-olds exceeds 1% in only three countries ?Cambodia, Myanmar and Thailand. In other countries, it is often far lower. In Indonesia, the world’s fourth most populous country, fewer than 5 people in 10,000 are living with HIV. In the Philippines, the rate of HIV infection is 7 per 10,000.

• Currently there are tremendous variations in the dynamics and trends of the epidemic within Asia. There are also significant variations within countries, especially within huge and populous nations such as China and India. For example, while some states of India show almost no HIV infection, others have reached adult prevalence rates of 2% and above.

• Despite this diversity, there are broadly recognizable patterns. In some countries, the virus has already spread considerably in the heterosexual population. In others, the epidemic is concentrated among injecting drug users and their sex partners, and HIV rates in the general population are low. In the latter countries, it is misleading to take the national HIV rate among adults as a yardstick of the severity of the epidemic or its scope for expansion.

• Epidemics driven by unsafe drug-injecting practices dominate in some provinces of China, Malaysia, Nepal and Viet Nam. Recent reports suggest that a similar situation is emerging in Indonesia, specifically in the capital, Jakarta.

• In parts of north-east India, too, widespread injecting drug use provided an early entry point for HIV. In Manipur, the prevalence of HIV infection among injecting drug users shot up from virtually nothing in 1988 to over 65% just four years later. It has remained at these high levels ever since. Most cases of infection among women appear to have been acquired from husbands who had been infected in turn by sex workers, themselves part of a longer chain of transmission. In other parts of the country, there is evidence that unsafe sex is spreading HIV within the general population.

• At present, China’s epidemic is mostly concentrated among injecting drug users in a few provinces in the south and west. There is huge potential for deterioration, however, not only through drug use but through unsafe sex. Against a backdrop of far-reaching social and economic change over the past decade, China has seen a dramatic rise in the classic sexually transmitted diseases such as syphilis and gonorrhoea ?evidence of widespread sexual risk behaviour.

• China and India between them account for around 36% of the world’s population. With such huge populations, even low HIV prevalence rates translate into huge numbers of infections. In India, where only 7 adults in 1000 are infected, 3.7 million people were living with HIV/AIDS at the beginning of the millennium ?more than in any other country in the world except South Africa.
• Countries where HIV has spread significantly through unsafe sex include Cambodia, Myanmar and Thailand.

• Thailand’s well-publicized success in curbing a rampant heterosexual epidemic has brought to light other routes of transmission against which HIV prevention programmes have been far less successful. HIV continues to spread virtually unchecked through the sharing of drug-injecting equipment and through unprotected sex between men.

• Myanmar is already in the throes of a major epidemic while Cambodia has the highest HIV prevalence rates in the region, fuelled by sexual transmission against a background of social and economic fragility.

• Viet Nam’s HIV epidemic, until now largely confined to the south and the central provinces, has expanded to the northern provinces as well. There, as in the rest of the country, the virus is spread through injecting drug use and there is ample evidence of steadily increasing sexual transmission.

• A number of factors have played a significant role in the spread of HIV in Asia and are likely to continue having an impact: injecting drug use, commercial sex, and migration and population mobility.