The global epidemiology of HIV

An estimated 33 million people were living with HIV worldwide at the end of 2007. Overall global declines in the rate of new HIV infections and AIDS deaths, notably in sub-Saharan Africa, indicate some successes in prevention and greater access to antiretroviral therapies. Nevertheless, a staggering 2.7 million people became infected with HIV in 2007. Moreover, the declines in some regions were partially offset by a rise in new infections in other parts of globe, in particular Asia and eastern Europe. New infections continue to disproportionately impact vulnerable populations, including young women and girls, men who have sex with men, sex trade workers, people who inject drugs and migrants. Prevalence rates of HIV infection among these populations, where data exist, are high. High-quality epidemiological information and robust statistical methods are vital in order to measure accurately the size of the epidemic, identify affected populations and track intervention efforts. Structural barriers, including social inequalities and the lack of prevention and intervention efforts aimed at vulnerable populations in many countries continue to hinder efforts to curb the global spread of HIV.