HIV, the virus that causes AIDS, "Acquired Immunodeficiency Syndrome," has become one of the world's most serious health and development challenges, since the first cases were reported in 1981: At the end of 2010, an estimated 34 million people were living with HIV globally, including 3.4 million children less than 15 years. The number of people newly infected in 2010 was 2.7 million. Almost all of those living with HIV (97%) reside in low and middle income countries, particularly in sub-Saharan Africa. Sub-Saharan Africa remained the most affected region in the global AIDS epidemic. This regions accounts more than two third (68%) of people living with HIV. Most children with HIV live in this region. Globally, the annual numbers of people newly infected with HIV continues to decline (Global HIV/AIDS Response progress report, 2011).