Ailan Li and Takeshi Kasai on behalf of Emerging Diseases Surveillance and Response, Division of Health Security and Emergencies, World Health Organization Regional Ofﬁ ce for the Western PaciﬁcAbstract: Health security in the Asia Pacific Region is continuously threatened by emerging diseases and public health emergencies. In recent years, the Region has been an epicentre for many emerging diseases, resulting in substantial negative impacts on health, social and economic development. As the Region is home to more than 50% of the world population, true global public health security depends to a large degree upon how successful this Region is in developing and sustaining functional national and regional systems and capacities for managing emerging diseases and acute public health events and emergencies. Tremendous efforts have been made by individual countries and the international community to confront emerging disease threats in recent years, but the need for a common regional strategic framework has been recognized by countries and areas in the Asia Pacific, the World Health Organization, donors and partner agencies. To address this need, an updated Asia Pacific Strategy for Emerging Diseases, or APSED (2010), has been developed, aiming to strategically build sustainable national and regional capacities and partnerships to ensure public health security through preparedness planning, prevention, early detection and rapid response to emerging diseases and other public health emergencies. The Strategy calls for collective responsibility and actions to address the shared regional health security threat with a greater emphasis on preparedness-driven investments in health security. APSED (2010) serves as a road map to guide all countries and areas in the region towards meeting their core capacity requirements under the International Health Regulations (2005) to ensure regional and global health security. A Continuing Threat to Health SecurityEmerging diseases pose a continuing threat to health security. In recent years, the Asia Pacific Region has been an epicentre for many emerging diseases (including re-emerging and epidemic-prone diseases) resulting in substantial negative impacts on health, social and economic development. Some of these diseases are severe acute respiratory syndrome (SARS); avian influenza A(H5N1); dengue; Nipah and Hendra viral diseases; leptospirosis; hand, food and mouth disease and pandemic influenza A(H1N1) 2009.Although it is impossible to predict what, where, when and how new infectious diseases will emerge, we can be confident that emerging diseases and public health emergencies will continue to occur. Factors driving disease emergence may include microbial adaption and evolution, increased international travel and trade, rapid urbanization, population growth, changes in human demographics and behaviour, climate change, continuous degradation of ecosystems, breakdown of public health measures and deficiencies in public health infrastructure (including inadequate sanitation).Need for a Common Strategic FrameworkAttempts to develop a global strategy for confronting emerging infectious disease threats were made more than a decade ago. However, due to significant emerging disease outbreaks in recent years, more serious efforts have been made by countries and the international community to confront these threats. Many countries have invested in enhancing their fundamental public health surveillance and response systems. Various new programmes, projects and networks related to emerging diseases have also been initiated with the involvement of national governments, international organizations, development agencies, donors and partners (including the private sector) and academic or educational institutions. These efforts have helped improve the overall preparedness for emerging diseases in the Region and globally.The experiences and lessons learned from implementation of the original Asia Pacific Strategy for Emerging Diseases, or APSED (2005), and pandemic (H1N1) 2009 showed a clear need for harmonization, prioritization, coordination, collaboration and efficiency in addressing the common threats. Such a collective approach required an up-to-date, agreed upon strategic framework that is relevant to all countries, regions and international stakeholders. The World Health Organization (WHO), as the directing and coordinating agency for international health within the United Nations system, has played an essential role in developing such global and regional public health policies and strategies in consultation and collaboration with countries and areas, technical experts and partners. Global and regional strategies can be tailored for national use based on country and area needs and context.