THE EBOLA VIRUS: Examining link between deforestation and emergence of the virus using GIS analysis

G.I.S. ANALYSIS

Methodology for GIS Analysis

· Assumption

The main assumption is that the reservoir species could come into contact with humans because of the destruction of rainforest. If the forest had not been disturbed, it is very possible that the virus would have continued its life cycle within the deeper regions of the rainforest, as a part of normal ecosystem cycles.

· Digitising and conversion to ArcView files

In this section, the maps of forest covers for Zaire and Gabon have been downloaded from the World Conservation Monitoring Centre (WCMC) and have been digitised using AutoCad, using the World Co-ordinate System (WCS). The locations of outbreaks were identified from published material and from the internet and the locations of these places were fixed using AutoCad.

The Maps of forest cover were then converted to ArcView files using a Mercator Projection and the locations of outbreaks were overlaid as new themes, over the existing forest themes.

The locations of outbreaks selected were the major outbreaks in Zaire and Gabon. Unfortunately a forest cover map for Sudan could not be obtained, which was the location of another large outbreak. The location of the Sudan outbreak however has been overlaid on the map of Zaire, since the location was very close to the border of Zaire and also close to the region of the Zaire outbreak.

· Results of the Analysis

The actual work in GIS took a relatively long time, but the results of the analysis can be summed up in one sentence

‘From the results of the overlay, there seems to be a very strong and definite relationship between the areas of Ebola outbreaks and areas of destruction of tropical rainforest’.

The G.I.S analysis is just a tool to add emphasis and physical evidence to the claims and conjectures of this case study. It seems very unlikely that there is just a mere coincidence between the locations of Ebola outbreaks and vast tracts of destroyed forest.

Gabon
(Ref. Map 1)

The outbreaks in Gabon took place in Makokou, and near the capital, Libreville. The former outbreak area was 150 km north east of the provincial capital of Makokou along the river Ivindo. The region of the outbreak coincides with a huge tract of degraded forest in the proximity of the river. Since the river is easily navigable, the areas which are deforested first, usually follow river reaches. The outbreak near Libreville also coincides with an area of degraded tropical rainforest, as well as area adjacent to ecologically sensitive mangrove forests which have their own unique ecosystem.

Zaire
(Ref. Map 2)

The first outbreaks occurred in Sudan and Zaire. The map of Zaire shows the locations of the Bumba and Kikwit outbreaks (ref. Table 1) along with the Maridi outbreak in south western Sudan. The Kikwit outbreak was the first outbreak which was so well documented. The Kikwit outbreak took place on the borders of the rainforest, in a region close to areas where forest has been degraded along the river system. (Also refer to Fig 11)