Over the past two decades, increasing concern and attention have been directed at the potential problems and threats associated with new and emerging diseases. This has been driven by fears arising from the rapid emergence, spread and public health impact of several recent outbreaks, such as the international spread of severe acute respiratory syndrome coronavirus (SARS-CoV) (2003), the potential of avian influenza H5N1 to emerge as a highly lethal pandemic as increasing numbers of human cases are reported (2003 and continuing), and the very rapid global spread of pandemic H1N1 influenza in 2009–2010. The emergence of SARS-CoV, in particular, demonstrated the considerable economic, political and psychological effects–in addition to the impact on public health–of an unexpected epidemic of a highly infectious, previously unknown-agent in a highly connected and interdependent world. These examples clearly highlight the necessity and importance of global outbreak surveillance for the early detection and response to new potential threats. They also demonstrate clearly that these emergent diseases can move rapidly between countries and continents through infected travellers so that surveillance needs to be transparent and authorities made aware of international disease events elsewhere around the globe. Some of the specific threats to the Asian Pacific region have been reviewed elsewhere.

It is now 10 years since the world was faced with the first severe and readily transmissible new disease of the 21st century – severe acute respiratory syndrome (SARS). Unknown and unrecognized, it emerged in late 2002 as the probable cause of an outbreak of atypical pneumonia in Guangdong Province, southern China. It then spread to Hong Kong Special Administrative Region (China) via an infected traveller who arrived at his hotel on 21 February 2003 where he infected 15 other guests. They, in turn, travelled to other countries carrying the new disease and initiating outbreaks in Viet Nam, Singapore and Canada. Three weeks later, with increasing numbers of cases among hospital staff in Hong Kong Special Administrative Region (China) and Viet Nam, the World Health Organization (WHO) issued a global alert on 12 March 2003 about this new acute respiratory syndrome of unknown etiology. However, the disease was spreading rapidly along major air routes, prompting WHO to issue an emergency travel advisory on 15 March, as well as naming the new disease “severe acute respiratory syndrome” and providing the first surveillance case definition.