Description of the study area
The field study was conducted alongside the Birbir River and its principal tributaries with a purpose of promoting and developing strategic tsetse control and disease management in the study and its surrounding areas. There are about five randomly selected districts Bure, Darimu, Lalo kile, Dale sadi, and Seyo located alongside of the Birbir River basin which is lengthways of west wards drains into Abbay River (Blue Nile) which crossing the Ethiopian/Sudanese border finally drains into Egypt. The Birbir River of southwestern Ethiopia is a tributary of the Baro River, which it creates when it joins the Gebba at the latitude and longitude 8°14′28″N 34°57′39″E. It is politically important because its course defines part of the boundary between the West Welega and Illubabor Zones of the Oromia Region . The study area has got sub-humid lowland climate to the southwest of the country that occurs between 1200 and 3020 meters above sea level at the escarpment of the valley with annual temperature ranging from 160C to 37 °C. It receives high and reliable annual rainfall with an average of 1050 mm precipitation per annum. The main rainy season lasts from mid-June to late September and the shorter one from April to May. The predominant farming system of the area is characterized by mixed livestock and crop production, with livestock playing a vital role in agricultural activities, nutritional values and income generation. An East African Zebu type breed of cattle, which are also known as Abyssinian short-horned zebu, found in the study areas. This type of cattle breed is characterized by a pronounced susceptibility to trypanosomosis; as high prevalence rate, high drug resistance and a high number of treatments. Cattle in the study area kept are under traditional extensive husbandry system with communal herding, [21, and 22].
Sampling Method And Sample Size Determination
Since there was an insufficient human or material resource to survey the whole area in detail and the area was heterogeneous in all respects (vegetation, climate, altitude, land use, distribution of human habitation, etc.) to isolate certain homogeneous, or similar, subareas, and to obtain a representative sample area a stratified sampling method was applied. The target populations were all local breed cattle of all age groups and sex found in each randomly selected study site. The sample size was determined by using Thrusfield formula (1995) with the expected prevalence of the disease in respective of the area was 50%, since there was no officially reported prevalence previously minimum of 384 heads of cattle. However, the conducted study was longitudinal and involves the maximum number of sample size .
Study Design And Methodologies
A longitudinal study was carried out from September 2016 to February 2018 with the primary objective of systematic evaluation of implemented strategic trypanosomosis and vector control activities based on the study parameters of the epidemiological association between Bovine trypanosomosis, vector challenge and anemia in upper Birbir valley.
Initially, during the late September 2016 baseline data were collected by conducting entomological, parasitological, and hematological surveys to estimate the epidemiological association between Bovine Trypanosomosis, vector challenge and anemia in upper Birbir valley which was considered as baseline study parameters before the strategic trypanosomosis and vector control activities were started.
Implemented strategic trypanosomosis and vector control activities were based on the use of Stationary attractive devices (targets), Ground sprays and Live bait techniques  which composes deployment of about 6,400 Deltamethrin 20% based chemical impregnated cloth targets baited with 3-week old cow urine between 150-meter distance along sides with Birbir river and tributaries, estimated area coverage of more than 1500 km2 Deltamethrin 20% based diluted to 0.02% ground spry along sides with Birbir river and tributaries, and impregnation of more than 85% of cattle population with Deltamethrin 1% pour-on application using T- bar spryer, with in all selected districts of Birbir valley for continuative three years between two periodic intervals per annum.
Finally, to evaluate the success of implemented control activities again entomological, parasitological and hematological surveys were conducted during early February 2018 and the epidemiological association between Bovine Trypanosomosis, vector challenge and anemia in upper Birbir valley were compared with baseline study parameters.
Entomological Survey Or Study
Before commencement of the study, a total of 375 monoconical standard traps baited with octenol (1-oct-3-nel), acetone (C8H16O); and 3 weeks old treated cattle urine were deployed in the main Birbir River and its principal tributaries sited in five randomly selected districts of Bure, Darimu, Lalo kile, Dale sadi and Seyo located alongside the Birbir River basin which is lengthways of westwards drains into Abbay River (Blue Nile). Traps were placed approximately 45 cm from the ground baited with the aforementioned odours placed in three different bait dispensers. The poles of traps were greased to prevent the possible fly predators, mainly ants. The traps were positioned for two consecutive days with a mean interval between traps of 250 meters, in most likely areas for finding tsetse, based on the presence of gallery forests, and the location of rivers and streams after clearing up to 2–3 meters’ radius of the trap site to enhance the visibility of the traps and to prevent from the possible fire damage. The traps were deployed in georeferenced locations to map and easily display the distribution of tsetse flies on the GIS map. The apparent density (arithmetic mean catches per trap per day) of flies was calculated by dividing the total number of tsetse flies captured (ΣF) by the product of the number of functioning traps used to catch them (T) and the number of days for which the traps were operational (D); FTD = ΣF /T × D. The identity of tsetse species present in the area was done using conventional identification keys of, Buxton1955 , Mulligan 1970 , FAO 1982a , Meharenet et al., 2020. Sex of all collected flies was identified by observing the posterior end of the ventral aspect of the abdomen by hand lens in which male flies were identified by enlarged hypopygium in the posterior ventral part of the abdomen which is absent in female flies.
Hematological Survey Or Study
Paired blood samples were collected from the auricular vein (marginal ear vein) of each animal using two haematocrit capillary tubes. The tubes were filled with blood ¾ of its height and sealed with crystal sealant. Packed cell volume (PCV) value for each collected blood sample was estimated, recorded and analyzed for the determination of anemia and comparison of infected animals with non-infected animals and only cattle with PCV ≤ 24% were considered as anemic .
Parasitological Survey Or Study
After the PCV value of each collected blood sample was determined the capillary tubes were cut 1 mm below the Buffy coat to include the top layer of RBCs. The content of the capillary tube was expressed on to a clean microscopic slid, mixed and covered with a coverslip. Then the slides were examined for trypanosomes based on the type of movement in the microscopic field. Confirmation of trypanosome species by morphological characteristics was done after staining with Giemsa and examination with oil immersion microscopy under × 100 power of magnification .
Finally, during sample collection; age, sex, Peasant Association, altitude and body condition of each animal were recorded. On subjective basis body condition of examined animals were evaluated during sample collection. They were classified as poor, medium and good relative to the average body condition of local animals (zebu) .
Data on entomological studies, collected from each deployed trap, were coded into appropriate variables and inserted into MS Excel Spread Sheet Program, 2010 (Microsoft Corp.) to create a database and transferred to STATA- 12 software of the computer program. The data processing was carried out based on both qualitative and quantitative data analyzing methods. For the qualitative test statistical analytic methods, table, frequency distribution, mean, standard deviation, were some of the methods employed. On the other hand, for the quantitative test statistical analytic methods, the prevalence rate including point prevalence, the difference in mean tsetse density based on their respective sex ratio was analyzed using independent t-test; Chi-square (c2) test statistics was employed whether the results obtained were arose due to chance or not for the entomological data. The test statistics were used to test the overall disease prevalence with an absolute desired precession of 5% at the level of 95% confidence interval.