Hagos Ashenafi (Prof), Dr. Workineh ShibeshiDr. Nigatu KebedeEfrem, Degineh2019-08-092023-11-302019-08-092023-11-302019-08http://etd.aau.edu.et/handle/123456789/18757PhD ThesisAfrican Animal Trypanosomosis remains one of the most important disease constraints to livestock and mixed crop-livestock farming in tropical Africa. Trypanosomosis is responsible for the death of 3 million heads of cattle yearly, with 50 million animals at risk in sub-Saharan Africa. The problem of trypanosomosis is still far from being solved due to the fact that trypanosomes affect multiple hosts, widespread trypanocidal drug resistance and antigenic variation displayed by the trypanosomes. Trypanocidal drugs: Isometamidium chloride (ISM) and Diminazene aceturate (DA) are the most widely used drugs for control of animal trypanosomosis in Ethiopia. In Kellem Wollega, trypanosomosis is one of the main livestock diseases. In the area, a number of brands of trypanocidal drugs from various sources are routinely used by veterinary professionals as well as farmers, which may result in rampant misuse and under-dosage of the medications, actions which might contribute for the emergence of trypanocidal drug resistance. However, study on trypanocidal drug resistance is not yet carried out despite of serious complains of drug failure from professionals and farmers. Therefore, the present study in Gidami and Sayo selected districts of Kellem Wollega Zone of Oromia Regional State; Ethiopia was designed to investigate the problem of bovine trypanosomosis with special emphasis on epidemiology of the disease and assessment of trypanocidal drug resistance. Accordingly, questionnaire survey, cross-sectional studies and field trypanocidal drug resistance trial on naturally infected cattle were used to assess the epidemiological picture of the disease and the utilization of trypanocidal drug practices and evaluate the current status of trypancidal drug resistance trypanosomes. In the questionnaire survey, a total of 100 farmers were interviewed, of which 50 from Gidami and 50 from Sayo districts to assess the knowledge, attitude and practices of farmers towards the control of bovine trypanosomosis. A cross-sectional vector survey was conducted in purposively selected eight villages of Gidami and Sayo districts from November, 2015 to June, 2017 in early dry and early rainy seasons. A total of 160 traps (80 per district) were deployed at approximate intervals of 100 to 200 meters for 48 hours at watering and grazing points of animals in two seasons. For cross-sectional study of bovine trypanosomosis a total of 1790 blood samples were collected from systematically selected cattle and examined by buffy coat blood examination technique during early dry and early rainy seasons in Gidami and Sayo districts. Based on the outcome of the cross-sectional study Kellem and Gry Sonka villages from Gidami district were selected for field trypanocidal drug resistance study. An abbreviated 28-day field prototudycol was used to estimate resistance to 1 mg/kg b.w ISM and 7.0 mg/kg b.w DA trypanosome-positive cattle. For this purpose a total of 100 parasitaemic cattle from Kellem and Giray Sonka villages were selected and treated with Isometamidium chloride and Diminazene aceturate and monitored for trypanosomes and packed cell volume (PCV) levels on days 14 and 28 post treatment. Based on the questionnaire survey, 100% of the respondents from Gidami and Sayo district indicated trypanosomiasis as the major important disease of livestock causing considerable direct and indirect economic losses. Isometamidium chloride and Diminazene aceturate are the commonly used drugs to treat bovine trypanosomosis in both study districts. Sixty percent of respondents from Gidami and only 9% from Sayo districts disclosed that they treat their animals nine to fifteen times per year per animal. Trypanocidal treatment failures were reported by 98% and 76% of the respondents from Gidami and Sayo district, respectively. Among 3289 flies trapped during the study period 1739 (52.88%) were Stomoxys, 1158 (35.21%) Glossina, 252 (7.66%) Tabanus and 140 (4.25%) were Haematopota. The overall apparent fly density was 10.28 flies per trap per days. The apparent density of Glossina, Stomoxys, Tabanus and Haematopota were 3.62, 5.43, 0.79 and 0.44 flies per trap per day, respectively. Four Glossina species: G. tachinoides, G.m.sub-morsitans, G. palidipes and G. fuscipes were recovered in Sayo district. However, only G.m.submorsitans and G. palidipes were caught in Gidami district. Out of the total 1158 tsetse flies caught, 51.81% were G. pallidipes; the remaining 25.65%, 16.58% and 5.96% were G. m. submorsistans, G.fuscipes and G. tachnoides, respectively. The overall prevalence of bovine trypanosomosis was 14.08% (95% CI: 12 -16%) and 11.16 % (95% CI: 9-13%) in Gidami and Sayo districts, respectively. However, there was no statistically significant difference (P > 0.05) between these two districts in the prevalence of bovine trypanosomosis. In the present study, the trypanosome prevalence was higher in low altitude (18.09, 13.80%) compared to mid altitude areas (9.13, 8.5%) in Gidami and Sayo districts respectively. The observed difference was found to be statistically significant (P<0.05). Trypanosoma congolense being the predominant species (57.30%) followed by T. vivax (29.10%), T.b.bruci (9.70%) and mixed infection of T. vivax and T. congolense (3.90%) were the prevailing trypanosome species in the area. The overall bovine trypanosomosis prevalence was siginificantly varied between poor (25.37%) compared to both medium (10.02%) and good (2.66%) body conditioned animals and between adult (14.16%) and young (9.38%) age categories. There was no statistically significant difference (P>0.05) in the prevalence of bovine trypanosomosis between sexes of the examined animals. There was a statistically significant difference (P<0.05) in the mean packed cell volume (PCV) between parasitaemic (21.53%) and aparasitaemic cattle (26.11%) regardless of district and season of sampling. The results of field trypanocidal drug resistance study confirmed the presence of drug resistance to the maximum recommended doses of ISM and DA in Giray Sonka and Kellem villages of Gidami district. From 50 trypanosome positive cattle treated with ISM 2% solution of 1 mg/kg bw, 68% had persistent infections at day 28 post treatment. Similarly, of the 50 trypanosome positive cattle treated with DA 7% solution of 7 mg/kg bw, 36% had persistent trypanosomes at day 14 post treatment. In conclusion, bovine trypanosomosis is a major disease constraint of livestock health and agricultural activity in Gidami and Sayo districts of Kellem Wollega Zone of Oromia Regional State, Ethiopia. Trypanocidal drug resistance is a threat in Kellem Wollega and thus sustainable and integrated tsetse and trypanosomosis control practices should be implemented to ensure productivity of cattle and foster agricultural development. Furthermore, extensive data on trypanocidal drug sensitivity tests using advanced molecular techniques is essential.enBovineTrypanosomosisTrypanocidal drug resistanceThesis