Assessment of Human African Trypanosomiasis Foci using Change Detection Algorithms

Abstract

Environ-climatic change influences the occurrence and propagation of Human African Trypanosomiasis (HAT), focusing on two foci; Delta State and Jigawa State Nigeria where HAT has been reported. Geospatial and temporal based ground truthing exercise carried out to harvest HAT vector in Jigawa state did not yield any results; this indicates that the disease might have been phased out in the state.  In the same vein, resurging of HAT disease in the Delta State has been reported of recent. Thus, a change detection analysis was conducted in a geographic information systems (GIS) environment, to investigate the foci landscape. Using normalised difference vegetation index (NDVI), normalised difference water index (NDWI) and tasseled cap transformation (TCT), changes with a lag time of two decades was assessed for the two foci.  The analysis suggested that the landscape has changed considerably over the years that show Delta State as the potential active HAT foci as explained from the regression analysis of 0.9868 (99%) ahead of Jigawa state 0.0000 (0%) that can be regarded as non-active foci.  However, on-going programs, such as afforestation, forestation, irrigation farming and water reservoir projects may result in re-introduction of favourable landscape, thus, re-invasion of the area by the HAT vector. Therefore strategies that will maintain the present HAT-free status of the non-active foci, without adverse effect on the environment should be a government priority. To effectively reduce or control HAT propagation, integrated prevention schemes should be developed and executed.  The two HAT foci are of great economic importance; Delta State landscape is rich in hydrocarbons while Jigawa State is known for its extensive grazing and arable landscape.

Keywords: Trypanosomiasis, Afforestation, Foci, HAT, Landscape, Environ-climatic, Spatial, Irrigation