Mapping the distribution of tsetse and animal trypanosomosis in selected districts of Uganda to facilitate targeting control measures

Abstract

Declining Government resources and donor aid for tsetse and trypanosomosis control have compelled countries to delegate control activities to farm-level veterinary extension personnel. While effective control measures such as chemotherapy, tsetse-trapping and restricted insecticide-treatment of livestock exist, implementation of such measures en masse has become increasingly impractical. Therefore mapping the distribution of tsetse and trypanosomosis hotspots was undertaken to ease targeting control measures by district administrative units in Amuria, Dokolo and Kaberamaido districts of Uganda. The districts were divided into grid sites using the program Arcview GIS 3.2. Villages representing the grid sites were physically identified through ground-truthing. Parasitological and tsetse surveys were then conducted in each village to establish the prevalence of trypanosomosis in cattle and apparent tsetse density. A total of 2430, 1304 and 1392 cattle were tested in Amuria, Dokolo and Kaberamaido districts, of which 230 (9.5%), 144 (11.0%) and 106 (7.6%) were detected positive, respectively. At village level, the prevalence of trypanosomosis ranged from 1-24%, 1-28% and 2-18% in Amuria, Dokolo and Kaberamaido districts, respectively. Tsetse surveys conducted concurrently in the respective villages revealed apparent tsetse densities ranging from 0.0-2.4, 0.6-13.2 and 0.6-9.0 flies/trap/day (F/T/D) in Amuria, Dokolo and Kaberamaido districts, respectively. Glossina fuscipes fuscipes was the sole tsetse species caught. Matching apparent tsetse densities at village level with their corresponding prevalences of trypanosomosis revealed that Amuria district had low tsetse densities with high corresponding prevalences of trypanosomosis, suggesting that cattle were encountering a high proportion of infected tsetse. In contrast, Dokolo district had high tsetse densities with low to medium corresponding prevalences of trypanosomosis, suggesting cattle were encountering a low proportion of infected tsetse. Kaberamaido district had low tsetse densities with corresponding low to medium prevalences of trypanosomosis, suggesting that cattle were equally encountering a low proportion of infected tsetse. Mapping to highlight hotspots was anticipated to facilitate planning and prioritization of resources for targeting tsetse and trypanosomosis control by district departments of veterinary services.

Keywords: Animal trypanosomosis; Control; mapping; prioritization of resources; Tsetse flies; Uganda