India leads world in number of AIDS cases

Source
The data released by UNAIDS shows that India now has the largest number of people living with HIV/AIDS. With an estimated 5.7 million infections, it has surpassed South Africa's 5.5 million.

But the epidemic still remains at its worst in sub-Saharan Africa, where per capita rates continue to climb in several countries. A third of adults were infected in Swaziland in 2005. By comparison, India's per capita rate is low, at 0.9 percent of its 1.02 billion people.

Here is the complete UNAIDS report.
In this report, China, the most populous country in the world, has about 650,000 HIV infections.