Between 5.5 and 6 million people are infected with HIV in South Asia.
India has more than 60% of Asia's estimated HIV infections.
It is a highly concentrated epidemic - almost 70% of HIV/AIDS cases in India are in only 8 states: Tamil Nadu, Karnataka, Andhra Pradesh, Maharashtra, Goa, Manipur, Nagaland, and Mizoram.
HIV prevalence varies greatly between and within districts, and even across villages in the same areas.
High-risk behaviors - injecting drug use and unprotected commercial sex - drive the epidemic.
To date, generic approaches have failed to address the major epidemic factors in local contexts.
In Nepal, for example, only 6% of the budget of the National Centre for AIDS and STD Control has been spent on harm reduction programs for injecting drug users, although injecting drug use is a major driver of the HIV epidemic in Nepal.
In India, most NGOs have focused their HIV prevention work on migrant men rather than on the one million sex workers who are considered an extremely vulnerable group for HIV transmission.
Reaching people at risk is the greatest challenge.
Halting the spread of the epidemic will depend on a two-pronged approach:
Establishing effective prevention programs for groups at increased risk of HIV infection such as sex workers and their clients, injecting drug users, and men who have sex with men
Resolving the social and economic factors of the epidemic such as poverty, stigma, and sex trafficking of women.