In the sections about vectors, parasite and hosts it is possible to appraise how GIS and RS are able to assess and analyse environmental parameters and phenomena that influence the T&T problem. Spatial analysis and satellite or aerial images have also a great potential for monitoring the extent of environmental impact of control strategies.

It is possible to separate the environmental impacts of controlling Trypanosomosis into two distinct types: direct and indirect. The former relates to the effects of insecticides on non-target organisms, water chemistry, nutrient cycle and people; the latter includes decreased morbidity and mortality of cattle and other animal species, increased grazing and agricultural expansion. While direct impacts have been largely studied, indirect ones have received much less attention, in part because they are more difficult to determine but also because they are far more difficult to regulate. Two main questions are important to understand the indirect environmental impacts of Trypanosomosis control:

• How does controlling the disease affect the pattern (change) and rate of land use/land cover?

• If these changes occur, how do they affect ecosystem function?`

Remote Sensing has already been used widely to map land use changes as a consequence of multiple socio-economic and eco-climatic factors, including tsetse control measures and local fly elimination campaigns. Some of the changes resulted in excessive land clearing that led to the over-exploitation of the natural resources and the degradation of the soil. The shift in land use was quite often followed by a loss of biodiversity, particularly in riverine forests that generally harbour rich animal niches and biotopes.

The decline in bio-diversity is only one of the negative impacts on the ecosystems. Therefore, this phenomenon, together with the proper land and natural resource management, requires great attention for planning sustainable agricultural development. A comprehensive study of the ecosystem goods and services which may be indirectly affected by tsetse control measures is yet to be done and it will certainly require a substantial effort and a multidisciplinary approach. Among the many ecological goods and services provided by wildlands that might be under threat we can mention water recycling, soil erosion protection and soil fertility, natural genetic diversity, access to fuelwood and timber.

GIS has been also used to forecast the impact of population expansion on tsetse distribution. Fine-grained human density maps have been modelled to derive future scenarios and the relevant contraction of tsetse habitat. The study managed to depict the areas where the fly presence is forecast to decline and concluded that none of the species will be under threat of extinction in the near future.