Historians from Thucydides to William McNeill have pointed to the connections between disease and civil society. Political scientists have investigated the relationship of public health to governance, introducing the concept of health security. In Contagion and Chaos, Andrew Price-Smith offers the most comprehensive examination yet of disease through the lens of national security. Extending the analysis presented in his earlier book The Health of Nations, Price-Smith argues that epidemic disease represents a direct threat to the power of a state, eroding prosperity and destabilizing both its internal politics and its relationships with other states. He contends that the danger of an infectious pathogen to national security depends on lethality, transmissability, fear, and economic damage. Moreover, warfare and ecological change contribute to the spread of disease and act as "disease amplifiers." Price-Smith presents a series of case studies to illustrate his argument: the Spanish influenza pandemic of 1918-19 (about which he advances the controversial claim that the epidemic contributed to the defeat of Germany and Austria); HIV/AIDS in sub-Saharan Africa (he contrasts the worst-case scenario of Zimbabwe with the more stable Botswana); bovine spongiform encephalopathy (also known as mad cow disease); and the SARS contagion of 2002-03. Emerging infectious disease continues to present a threat to national and international security, Price-Smith argues, and globalization and ecological change only accelerate the danger.