With the global population approaching seven billion and international access to commercial air travel expanding, the number, frequency and scale of human congregations has increased dramatically during the past half century. Today, mass gatherings of hundreds of thousands to millions of people from all corners of the globe have become common. Such gatherings are held for a multitude of reasons: religious (e.g., the Hajj), political (e.g., Group of 20 [G-20] summits), socio-cultural (e.g., World Pride) and sports-related (e.g., Olympic Games), to name a few.1 Despite their importance, mass gatherings carry the risk of locally amplifying and subsequently disseminating infectious disease threats around the world.2 When travellers attend a mass gathering, they may unknowingly introduce infectious agents acquired in their home environments. In settings conducive to the spread of infection, epidemics among attendees and their contacts may ensue.3,4 Those who are exposed may subsequently transport the infectious agents internationally, spawning new epidemics in other parts of the world.5
Current efforts to prepare for infectious disease threats at mass gatherings are generally led by the host country, often in collaboration with international public health agencies.2 Such efforts employ strategies that are directed, for the most part, at the site of the gathering. These may include enhanced surveillance, infection control measures to minimize the transmission of disease and ensuring the availability of resources to enable rapid response to an epidemic, should one arise. However, these efforts do not typically take into account a broader understanding of the populations attending the mass gathering and the risks associated with infectious disease threats at their points of departure. We propose a conceptual model that could complement existing preparedness efforts by expanding the geographic perspective of public health surveillance worldwide at a time when large numbers of people from around the globe are travelling to attend a mass gathering. Using this model would provide public health experts with the opportunity to identify and deal with an infectious disease threat at its source and, failing that, at the site of the mass gathering. This approach could potentially prevent importation of infection by persons travelling to the site of the mass gathering and/or exportation of infection as attendees at the gathering return home.
Recent innovations in public health surveillance, such as the Canadian-based Global Public Health Intelligence Network, permit real-time global situational awareness (by leveraging media reports on the Internet) that typically outperforms traditional surveillance efforts and that exists outside politically influenced communication channels. By integrating knowledge of worldwide patterns of commercial air traffic6–8 with global surveillance of infectious diseases via Web-based intelligence-gathering tools,9,10 the conceptual model presented here seeks to identify locations in the world from where large numbers of people are expected to travel to attend a mass gathering and where infectious disease threats of public health significance are reported. This integrated knowledge could be used to notify officials at the site of the gathering of an emerging international threat and could foster a culture of greater international cooperation by motivating cities and countries that share common risks of infectious disease threats to work collaboratively. Herein, we apply our conceptual model to the Vancouver 2010 Olympic and Paralympic Winter Games.