Health issues occasionally intersect security issues. Health security has been viewed as ail essential part of human security. Policy makers and health professionals, however, do not share a common definition of health security. This article aims to characterize the notions of health security in order to clarify what constitutes the nexus of health and security. The concept of health security has evolved over time so that it encompasses many entities. Analyzing the health reports of four multilateral organizations (the United Nations, World Health Organization, Asia-Pacific Economic Cooperation, and the European Union) produced eight categories of most significant relevance to contemporary health security, allowing comparison of the definitions. The four categories are: emerging diseases; global infectious disease; deliberate release of chemical and biological materials; violence, conflict, and humanitarian emergencies. Two other categories of common concern are natural disasters and environmental change, as well as chemical and radioactive accidents. The final two categories, food insecurity and poverty, are discussed less frequently. Nevertheless, food security is emerging as an increasingly important issue in public health. Health security is the first line of defence against health emergencies. As globalization brings more complexities, dealing with the increased scale and extent of health security will require greater international effort and political support.
