The global AIDS pandemic furnishes a case study for many of the themes addressed throughout the course. While in the developed West the disease largely afflicts concentrated high-risk groups such as intravenous drug users and the sexually promiscuous, in Southern Africa it is much more a generalized disease of poverty. In countries such as Botswana and Swaziland, the economic and social consequences of the disease have created a vicious circle, whereby the devastation wrought by AIDS severely impedes public health efforts and prepares the way for further infection. One important lesson that has been drawn from the past decades of struggle against the epidemic is therefore to take account of the specific, local characteristics of each affected area, making provision for the social as well as purely biological factors of transmission.