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Learning from Epidemics

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In 2003 an unknown virus suddenly emerged in Guangdong China and proceeded to spread rapidly around the world. The SARS coronavirus disseminated around the world via the global air transportation network with stunning efficiency, highlighting one of the unintended consequences of the globe’s vast airline system. After the SARS outbreak, a group at St. Michael’s Hospital in Toronto, took it upon themselves to study the SARS outbreak in detail. The end goal to develop effective strategies to deal with future epidemics. Their project dubbed Bio.Diaspora took a multidisciplinary approach in analyzing air traffic patterns and the distribution of infectious diseases. Their self proclaimed mission:

Understand global patterns of human travel via commercial airlines as a way to predict how emerging infectious diseases are most likely to spread around the world – and consequently apply this knowledge to help the world’s cities and countries better prepare for and respond to global infectious disease threats of tomorrow.

The Bio.Diaspora team believed that not only more applied research into the impacts of global population mobility on public health and security is necessary, but access to quality data on global air transportation and traffic patterns is needed as well. They sought to fulfill this need by:

[D]eveloping a data warehouse for the sole purpose of conducting methodological and applied research on commercial air travel and emerging infectious disease threats. This report embodies rigorous analysis of these data from multiple scientific perspectives – medicine, infectious diseases, public health, health policy, biostatistics, geographic sciences, network analysis, computer sciences, and mathematical modeling.

Their thorough analysis accounted for numerous factors and yielded a report just prior to the emergence of the H1N1 influenza (Swine Flu) pandemic. One of the really interesting parts of the Bio.Diaspora report was the numerous simulations done on potential H5N1 avian influenza transmission from emergence in numerous potential cities around the world.

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Click through for interactive version.

The above graphic illustrates the likelihood of importation of H5N1 avian influenza into various areas of the world with an epidemic beginning in São Paulo, Brazil. This caught my eye as it seemingly foreshadowed the H1N1 epidemic. After the emergence of H1N1, the Bio.Diaspora team went back to study the air traffic patterns of the initial stages of the spread (March and April 2009) from Mexico. Running simulations like those from the Bio.Diaspora project’s report they were able to produce predictions based on the flight itineraries (data shown below) that correlated highly with the observed transmission pattern. Their complete analysis is published in the New England Journal of Medicine.

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Destination Cities and Corresponding Volumes of International Passengers Arriving from Mexico between March 1 and April 30, 2008.

The Bio.Diaspora project team’s work on both the SARS epidemic and now the H1N1 pandemic illustrate that there’s still much to learn about managing public health crises on a global scale thanks to the highly interconnected nature of today’s cities. It’s a much smaller world now and new tools and ideas will be necessary to deal with future emerging diseases.

(Bio.Diaspora)(Spread of a Novel Influenza A (H1N1) Virus via Global Airline Transportation)

Written by Anthony

July 9th, 2009 at 12:00 am