In the past two decades, many novel´ viral diseases have struck the world. The latest is avian influenza, which has triggered major epidemiological and surveillance studies worldwide, as well as research into the molecular and physiological characteristics of the virus responsible, H5N1. Previously, a novel coronavirus was identified as the aetiological agent oft he severe acute respiratory syndrome (SARS), a new respiratory viral disease that emerged at the end of 2002 and caused profound disturbances in over 30 countries in 2003. Although this epidemic has been controlled by isolation, much about the virus remains unknown, particularly its origins and potential reservoir(s). This book critically evaluates the scientific evidence on these viruses, including molecular biology, diagnostics, animal models of viral infection, plus the development of vaccines and anti-viral agents. Virologists from different countries summarize the latest advances in epidemiology, virus identification and public health measures for protection and prevention. Representatives from Canada, China, Hong Kong, Taiwan and Singapore, which had the most cases of infection and the most severe social and economic disturbances, provide critical reviews of problems and solutions encountered during the SARS epidemic. The book also evaluates what was learned from previous flu outbreaks. Representatives from South-East Asian countries review recent bird-to-human avian influenza virus transmissions in their countries and share their experiences in the implementation of effective disease surveillance and control strategies.