Influence of Climate Variables on Vector and Prevalence of Bovine Trypanosomosis in Tselemti District, North West Tigray, Ethiopia

Abstract

The present cross sectional study was conducted from December 2013 to September 2014 to assess the influence of climatic variables on the vector and prevalence of bovine trypanosomosis in three sites of Tselemti district, Northwestern Tigray, Ethiopia. A total of 500 cattle were considered to know the prevalence of the disease using parasitological approaches, and a total of 15 traps were deployed in the study area to assess biting flies and their distribution. Impact of climatic variables on vector population dynamics and distribution as well as the prediction of the disease incidence for the three terms (2013–2099) with respect to the climatic variables was done with climatic models. Arc GIS software (version 9.3) was used for spatial disease and vector distribution analysis. The future time series was constructed by the statistical downscaling technique using predictor variables of HadCM3A2a and HadCM3B2a. The overall prevalence of trypanosomosis in cattle was 8% and a significant variation (p < 0.05) was observed between agro-ecology classes. Out of 6211 biting flies caught in the study area, 2824 (45.5%), 163 (2.6%) and 3224 (51.9%) were of the genus stomoxis, tabanus and other biting flies, respectively. The biting fly population was higher in ‘moist-kolla’ (lowland) than ‘moist-weynadega’ (midland) and ‘moist-dega’ (highland). The result of the statistical downscaling model (SDSM) indicates in future three term periods; there will be an increase in temperature within a range of 0.51–1.49 °C and rainfall change within the range of 0.62–30.52% which affects the biology of the biting flies thereby influencing the incidence and distribution of trypanosomosis. Moreover, the focus group discussion indicated for a change in temperature and rainfall in the district. Particular attention should be given to T. vivax and fly population in relation to climatic variables and agro-climatic classes. Moreover, there should be controlled movement of animals from endemic to trypanosomosis free areas in the region to minimize the spread of the disease from lowland to highland areas.