Risk of Dengue Spread from the Philippines through International Air Travel

Epidemics of dengue fever occur every 3 to 4 years in the Philippines. The risk of a dengue fever outbreak in the Philippines has been heightened since Typhoon Haiyan struck the region in November 2013 because recovery efforts have been slow to progress. The structural damage caused by the typhoon resulted in an abundance of standing water, which can serve as mosquito breeding grounds. Should an outbreak of dengue occur, infected travelers departing the Philippines pose a risk because they may introduce the dengue virus into local vector populations (of Aedes aegypti and Aedes albopictus ) at their destinations. This study quantifies the risk posed by potentially infected travelers departing the Philippines by using a network model that incorporates predictive species distribution models, demographic features of destination areas, and air traffic volumes. The analysis reveals that a majority of travelers departing Philippine airports deplane in regions suitable for harboring Aedes aegypti or Aedes albopictus ; this factor increases the likelihood of further spread of the disease if an outbreak were to occur. Because it is impractical to implement all possible monitoring and control measures at all locations connected to the Philippines, this analysis ranks the set of candidates and thus allows surveillance resources to be optimally deployed.