This book examines the formation of scientific knowledge about the AIDS epidemic in the 1980s and shows the broader cultural assumptions which grounded this knowledge. Alex Preda highlights the metaphors, narratives, and classifications which framed scientific hypotheses about the nature of the infectious agent and its transmission ways and compares these arguments with those used in the scientific knowledge about SARS. Through detailed rhetorical analysis of biomedical publications, the author shows how knowledge about epidemics is shaped by cultural narratives and categories of social thought. Preda situates his analysis in the broader frame of the world risk society, where scientific knowledge is called upon to support and shape public policies about prevention and health maintenance, among others. But can these policies avoid the influence of cultural narratives and of social classifications? The book shows how culture matters for prevention and health policies, as well as with respect to how scientific research is organized and funded.