Εισαγωγή

Human immunodeficiency virus (HIV) is a retrovirus that destroys CD4 T cells and is the aetiological agent of acquired immunodeficiency syndrome (AIDS). [1] HIV is divided into 2 types, both of which cause AIDS: HIV 1, responsible for the global epidemic; and HIV 2, less pathogenic and restricted mostly to West Africa. [2] AIDS, which usually occurs after approximately 6 to 9 years of HIV infection, is a constellation of opportunistic and other infections, conditions, or malignancies. These occur as a result of increasing immune depletion over time. [3]

There are 33.3 million people infected with HIV worldwide, 22.5 million of whom are in sub-Saharan Africa, and the Caribbean is the second most heavily affected region of the world. [4] [5] AIDS was first identified in the US in 1981, and the US has the most severe HIV epidemic in the developed world. In the US, 49% of all newly diagnosed HIV infections in 2006 were among men who have sex with men. [6] In contrast, the sub-Saharan epidemic is predominantly heterosexual, with women comprising 60% to 70% of those infected with HIV. Overall, globally, the HIV incidence rate is believed to have peaked in the late 1990s and subsequently stabilised, notwithstanding increasing incidence in a number of countries.