In our Mesoamerican context and the global tropic in general, Dengue is a common disease during the rainy season. Knowing where the greatest number of incidents are occurring is surely an exercise in which GIS applications offer valuable results.
I remember that when I was a child, dengue was not mortal like now; just a week of rest with fevers, muscle pain, a lot of fluids and the regret of not being able to play a good game of football in the mud with the friends of the neighborhood. Today is deadly, if someone does not attend the doctor can die in two days in a despondent fall of platelets.
But the problem of dengue in urban areas of Mesoamerica is not easy to solve. The damn insect (Aedes aegypti) lives in clean, stagnant waters, so it can be either on a tire of a vacant lot or in the pot of a plant. Finally, the way to combat it is the destruction of hatcheries combined with fumigation. Without spatial information, this work can be endless and unproductive.
An interesting exercise in the application of Geographic Information Systems to research in health aspects is the case of Taiwan. The objective is to analyze how infected mosquitoes are transferred between habitats and, in this way, to detect the main transmission corridors between each period of time. Therefore, spatial and temporal dimensions are considered simultaneously.
By establishing an ecological network, researchers can identify the habitat of infected mosquitoes and calculate possible routes of their movement and prevent them from moving through these corridors.
According to the results of this research, which undermines the intensity of the connection of ecological networks by restricting transmission corridors of infected mosquitoes, the spread of dengue fever can be effectively controlled. The three research objectives are:
- Using ecological network analysis to detect suspected key transmission corridors for the movement of infected mosquitoes during and between each period of time.
- Make the recommendation related to different key transmission corridors to curb the spread of infected mosquitoes.
- Adopt a GIS software to integrate the analysis data and results and to show the information on the map.
As a result, the following aspects can be obtained:
Space-time diffusion of dengue fever.
When it comes to the diffusion of space-time of the dengue epidemic, the human movement and the movement of infected mosquitoes is binding. Remember that the radius of flight of a mosquito is not higher than the 100 meters, with which the foci of infection are punctual; therefore its gradual propagation. If the route can be detected, it is possible to restrict it by means of external forces. Therefore, the key transmission corridors of infected mosquitoes can be detected and displayed with the GIS software, and the areas in which the corridors are recommended to be removed are also displayed on the GIS platform to control the spread of the epidemic of dengue
Relevant data from the Centers for Disease Control of Taiwan were captured, analyzed and displayed on a GIS platform for the search of the main transmission corridors of infected mosquitoes. Subsequently, the recommendation was made for the elimination of these key corridors to endanger the relationship between the intensity of each habitat and to achieve the objective of preventing the spread.
The Space-time Network for Habitats and the Movement of Infected Mosquitoes.
The space-time network consists mainly of layers of nodes and lines, which belong to different periods of time. Each node identifies the habitat where the mosquito eggs are found, is created in the center of the corresponding plot in the layer. And each line that connects two nodes represents the corridor of the two habitats in the range of motion of the mosquitoes. In addition, the lines can be divided into two types of link connecting two nodes in the same period layer time or different time period layers. A continuous line represents the possible transmission corridor in the same period, as long as the two endpoints are in the same period layer. Meanwhile, a dotted line represents the possible transmission corridor through two periods, provided that the two end points are in layers of different time. The ecological network of infected dengue mosquitoes is built according to the previous principle.
Calculation of the importance of each link
The analyzes are used within the ecological network and definition of space-time analysis to define the meaning of each link. In addition, the identification of neighboring topologies will allow to define the mutation relation of the vector.
Link types and attributes
According to the temporary characteristics of the links in the same or in different periods of time, and the results of the analyzes that include global link and local link. The link is considered the most important of all. An isolated element is synonymous with the possible and key corridor of movement transmission of infected mosquitoes. In addition, the link in the same or different periods reveal different transmission risk intensities. The superposition of layers of different types of links with the GIS Software, allows to visualize the main transmission corridor built in both the same and different periods.
In this case, the exercise was performed using SuperGIS Desktop
This is not new. We remember Dr. Snow's maps for the detection of dengue. In this case, the access we have to technologies differs and instead of being wastewater as in those times, it is a vector
For more information, you can see the Supergeo Technologies page.