Since the 1980s the world has witnessed the global emergence of new epidemic infections (HIV/AIDS being the most dramatic so far), and the reappearance of known infectious diseases, such as tuberculosis, malaria, and syphilis, that had seemed for some time to be under control. In the field of public health, these events have led to the designation of a new nosological category: emerging and re-emerging infectious diseases. Such diseases pose a growing threat to the hegemony of biomedicine, raising many questions about the adequacy of biomedical discourse and practices to meet the global challenge of infectious diseases. This chapter analyzes the construction of this new nosological category and examines the implications of (re)emerging diseases for public health, food security, and human development on a worldwide scale.