migration of young adults to urban areas increase Sri Lanka's vulnerability.

"HIV and AIDS can pose a serious economic and social development risk to countries in South Asia unless prevention programmes, targeting vulnerable groups at high risk of infection, are scaled up," it said.

The report argues that, even if the overall prevalence rate is low (up to 0.5 percent), there is high and rising HIV prevalence among vulnerable groups at high risk for HIV infection.

The vulnerable groups include sex workers and their clients, and injecting drug users and their partners.

"Without increasing prevention interventions among those at highest risk, these concentrated epidemics can further escalate," the report warned.

Overall, the number of people living with HIV and AIDS in South Asia is about 2.6 million, of whom the lion's share is in India.

AIDS accounts for 1.5 percent of all deaths in South Asia and about two percent of all deaths in India.

These numbers of deaths are comparable to the numbers from diabetes, tuberculosis, and measles.

The report finds the impacts of HIV and AIDS in South Asia on the overall level of economic activity to be small.

However, the direct welfare costs of increased mortality and lower life expectancy are more substantial, accounting for 3 - 4 percent of GDP in India and Nepal, respectively.

"Even in the low HIV prevalence countries of South Asia, there cannot be any room for complacency," said Mariam Claeson, World Bank HIV and AIDS Coordinator for South Asia.

"While the impact of HIV and AIDS on economic growth is small in South Asia, the welfare cost on households is by no means negligible."

The economic impact on individual households affected by the disease is substantial, the report said.

In a household study on India, 36 percent of people living with HIV and AIDS who were able to retain their employment nevertheless reported an income loss, which averaged about nine percent.

Among those who lost their employment (about nine percent), the income loss was severe, at about 66 percent.

Access to prevention and treatment, the report said, is strongly linked to socioeconomic factors such as gender, education, and wealth.

And, people's ability to cope with the financial effects of HIV and AIDS differs strongly. For example, the report finds that HIV and AIDS have a disproportionate economic impact on HIV-positive widows who face the double burden of living with HIV and AIDS and the low socioeconomic status of women.