Web-based GIS: the vector-borne disease airline importation risk (VBD-AIR) tool

Abstract

Background: Over the past century, the size and complexity of the air travel network has increased dramatically. Nowadays, there are 29.6 million scheduled flights per year and around 2.7 billion passengers are transported annually. The rapid expansion of the network increasingly connects regions of endemic vector-borne disease with the rest of the world, resulting in challenges to health systems worldwide in terms of vector-borne pathogen importation and disease vector invasion events. Here we describe the development of a user-friendly Web-based GIS tool: the Vector-Borne Disease Airline Importation Risk Tool (VBD-AIR), to help better define the roles of airports and airlines in the transmission and spread of vector-borne diseases.

Methods: Spatial datasets on modeled global disease and vector distributions, as well as climatic and air network traffic data were assembled. These were combined to derive relative risk metrics via air travel for imported infections, imported vectors and onward transmission, and incorporated into a three-tier server architecture in a Model-View-Controller framework with distributed GIS components. A user-friendly web-portal was built that enables dynamic querying of the spatial databases to provide relevant information.

Results: The VBD-AIR tool constructed enables the user to explore the interrelationships among modeled global distributions of vector-borne infectious diseases (malaria. dengue, yellow fever and chikungunya) and international air service routes to quantify seasonally changing risks of vector and vector-borne disease importation and spread by air travel, forming an evidence base to help plan mitigation strategies. The VBD-AIR tool is available at http://www.vbd-air.com.

Conclusions: VBD-AIR supports a data flow that generates analytical results from disparate but complementary datasets into an organized cartographical presentation on a web map for the assessment of vector-borne disease movements on the air travel network. The framework built provides a flexible and robust informatics infrastructure by separating the modules of functionality through an ontological model for vector-borne disease. The VBD‒AIR tool is designed as an evidence base for visualizing the risks of vector-borne disease by air travel for a wide range of users, including planners and decisions makers based in state and local government, and in particular, those at international and domestic airports tasked with planning for health risks and allocating limited resources.

Figure 1

2011 Air network data used in VBD-AIR. (a) The location of the 3,632 airports across the world; (b) the flight routes for 2011 captured within the VBD-AIR tool.

Figure 2

Example disease and vector distribution maps from the VBD-AIR tool. The predicted distribution of (a) chikungunya outbreak risk based on geolocated data on recorded outbreaks since 2008 combined with satellite-derived environmental covariates within a boosted regression tree species distribution prediction model. The color scale shows predicted unsuitable to suitable conditions for outbreaks as a continuous scale from yellow to dark blue. (b) climatic and environmental suitability for Aedes albopictus presence based on field survey data combined with satellite-derived environmental covariates within a boosted regression tree species distribution prediction model. The colour scale shows predicted unsuitable to suitable conditions as a continuous scale from yellow to dark blue.

Figure 3

The architecture of the VBD-AIR tool. VBD-AIR adopts a three tier design: Web Server Tier, Data Server Tier and a Map Service Tier. The web interface follows AJAX standards. The web server implements a Model-View-Controller (MVC) framework. The data server is an SQL database, employed in a snow-flake structure and interpolated in the web server as data entities. The Web Mapping Services hosts the coverage file for predicted disease and vector distributions on a GeoServer. The base map service retrieves maps from Google and OpenStreetMap.

Figure 4

Flow of user input for the VBD-AIR tool. Risk assessment functions for the VBD-AIR tool. “Imported disease risks”, “onward transmission risks” and “imported vector risks” are provided for the direct flight route scenario and the possible routes from endemic area via one transfer are provided for the indirect flight scenario.

Figure 5

User input example for the VBD-AIR tool. A sample user input for the VBD-AIR tool for a user interested in imported dengue infection risks to Miami in January. a) The user selects their airport, disease and month of interest; b) The result shows the direct flight routes from dengue suitable areas to Miami, and the user can select risk assessments that include imported disease risk and onward transmission risks; c) The result shows the direct and one-transfer flight routes from dengue suitable areas to Miami, and the user can navigate through all the results for more detailed information.