Tilahun, Geetachew PhD.Msangi, Shandalas2021-10-082023-11-082021-10-082023-11-081999-12http://etd.aau.edu.et/handle/123456789/28083A tsetse survey to assess the risk of trypanosomosis to livestock was conducted in the south wesern Rift Valley of Ethiopia. The Challenge was estimated at the Product of tsetse relative density. Infection rate and the Proportion of bloodmeal taken by tsetse flies from Livestock. A total of 2900 km2 of the study area was divided into 100 km2 Monitoriag grids and Stratified in three strata according to altitude as lowland (0-1600 m alitiude) mid-altitude (1601-2000 m altitude) and highland (above 2000 m altitude.) The survey was done twice according to this stratification first during the dry spell (April-mid May) and second in late June-July 1999 (wet). Twentyfive NG2U-traps were deployed in each grid. Few biconical traps were deloyed along the rivers to monitor riverine species. Traps were removed after three days.and the flies were counted. Identified and sexed.Relative densiy was calculated as the number of flies caught per trap per day. Tsetse infection rates were determined by dissection method. Aging of flies was done mainly by wingfray method. Bloodmeal identification was based on enzyme-linked immunosorbent assay (ELISA) using host specific antisera. Two tsetse species were detected,Glossina Pallidipes as the Predominant Species which was detected up to 1931 m above sea level and Glossina fussipes. Detected up to 1710 m altitude During the dry spell.the relative density of G pallidipes was 0.6 flies/trap/day and 0.06 flies/trap /day for G fuscipes. During the wet spell.these figures rose to 2.4 and 0.1 for G.Pallidipes and G.fuscipes respectively.The lowland areas recorded the highest density for both species. There were no flies caught in the highland area. About 915 G.pallidipes and 652 G.fuscipes were dissected for infection rate estimation. All flies were from lowland areas. For G.pallidipes. The overall infection rate was found to be 7.9%. There was a significaiontly higher infection rate in females (9.4%) than in males (4.1%) (x2=6.42.P < 0.05).The infection rate was also significantly higher in the wet (9.5%) than it was in the dry months (5.6%).(x2=4.57,P<0.05).All the three important pathogenic trypanosome types were detected.with an infection rate of 5.4%.2.2% and 0.2% for Vivax. Congolense and Brucet types respectively. As regard to G.fuscipes. the overall infecaion rate was found to be 7.6%.only Vivux and Congolense infection types were detecete Females also showed significantly higher infection rates (9.4%) than males (5.8%). (x2=4.68. P<0.05) There was no significant difference in the wet (7.8%) and dry period (7.7%0) (x2=0,p >0.05). The infecaion rate was 7.5% and 0.03% for Vivax and Congolense type infection respectively. During the dry spell.cattle were identified as the main source of bloodmeals for both G.pallidipes (45%) and with G.fuscipes (40%) in the wet spell cattle Providing only 66.7% of the bloodmeals for G. pallidipes while G.fuscipes changed their main host to man (69.2%) with cattle providing only 7.7% of their meals.Implication of this change are discussed. The trypanosomosis risk index (challenge) for individual tsetste species in dry months was estimated to be 152.5 for G.pullidipes and 18.6 for G.fuscipes. While in the wet spell.these index in dry months was 171 and in the wet months it was estimated to be 1527. It is concluded that the risk is higher in the wet than in the drier months of the year this finding corresponded well with tryanosome prevalence in animals According to the strtification of the altitude in this particular study the lowland was categorised as having medium to high tsetse challenge. mid-altitude as having low to medium challenge. while there was no challengi in the highlands. Fuscipes contributed very low to the overall challenge in the study area as compared to G.PallidipesenThe challenge was estimated at the Product of tsetse relative density.Thesis