The developing world is disproportionately affected by the HIV pandemic. In many countries in sub-Saharan Africa, HIV infection is established in the general population: in southern Africa, which is particularly severely affected, HIV prevalence among pregnant women reached around 40% by 2003 in some areas. Local epidemiology depends on the relative contribution of the three major routes of HIV transmission: sexual contact (heterosexual and homosexual); mother to child; and exposure to blood or blood products. The main route of transmission is sex between men and women....

The developing world is disproportionately affected by the HIV pandemic. In many countries in sub-Saharan Africa, HIV infection is established in the general population: in southern Africa, which is particularly severely affected, HIV prevalence among pregnant women reached around 40% by 2003 in some areas. Local epidemiology depends on the relative contribution of the three major routes of HIV transmission: sexual contact (heterosexual and homosexual); mother to child; and exposure to blood or blood products. The main route of transmission is sex between men and women....