Book excerpt: Today AIDS dominates the headlines. A century ago it was fears of syphilis epidemics. This book looks at how the spread of syphilis was linked to socio-economic transformation land dispossession, migrancy and urbanisation disrupted social networks - factors similarly important in the AIDS crisis. Medical explanations of syphilis and state medical policy, however, were shaped by contemporary beliefs about race. Doctors drew on ideas from social Darwinism, eugenics, and social anthropology to explain the incidence of syphilis among poor whites and Africans, especially women, and to help define 'normal' and abnormal sexual behaviour for racial groups.