Preliminary Study on Mechanically Transmitted Bovine Trypanosomosis and Management of Trypanocidal Drugs in Selected Peasant Associations of Tigray

ISSN 079-018 IDOSI Publications, 015 DOI: 10.589/idosi.apg.015.6.1.964 Preliminary Study on Mechanically Transmitted Bovine Trypanosomosis and Management of Trypanocidal Drugs in Selected Peasant Associations of Tigray 1 1 1 3 1 Birhanu Hadush, Berihun Afera, G. Aregawi, Nesibu Awol, A. Mulu and Kidane Woldu 1 Mekelle University, College of Veterinary Medicine, Ethiopia Tigray Bureau of Agriculture, Kafta-Humera-Veterinary Clinic Coordinator, Ethiopia 3 Private Practitioner, Mekelle City, Ethiopia Abstract: A cross sectional study was carried out in selected peasant associations of Tigray (Tanqua-abergelle, Ofla, Humera and Maytsebri) from April 011 to July 011 with the objective of assessment of mechanically transmitted animal trypanosomes and the management of trypanocidal drugs. Judgemental sampling was used to include a total of 510 (34,163 and 113 from Humera, Ofla and Tanqua-abergelle respectively). Parasitological examination of buffy coat smears indicated that an overall prevalence of T. vivax infection of 10.4%, 7.7% and 0.8% in Ofla Woreda, Kafta-Humera and Tanqua-Abergelle respectively. The association of the disease with sex and age was not statistically significant in both Ofla and Kafta-Humera. However; the association between the occurrence of the parasite and PCV level was statistically significant. The result of questioner survey indicated that the majority of the interviewees farmers agreed that trypanosomosis was serious disease affecting the survival and productivity of animals. Interestingly, some of the clinical signs indicated by them were similar with the clinical signs observed in clinical cases. However, the trend of indiscriminate use of Trypanocidal drugs is a frustrating event as it may lead to development of drug resistant strains. Generally, Trypanosoma vivax is a serious problem to livestock production in the study areas. It is concluded that extension work on training of farmers, training of field experts and developing and enforcement of drug use policy is the critical issue. Further more studies on drug resistance pattern of the parasite are of immediate action. Key words: Buffy Coat Smears Mechanically Transmited PCV Tigray Trypanosoma Vivax INTRODUCTION man gives rise to a disease that takes a variety of forms, sleeping sickness and the cattle trypanosomosis Livestock are the backbone of the socioeconomic Nagana [4]. The African Animal Trypanosomiasis systems of most of the rural communities in the continent (AAT) is one of the major threats for the Livestock in of Africa. However, it is difficult to realize more gain in Africa. About 9 million km of Sub-Saharan Africa, livestock production and productivity without first representing about one-third of the total land, is infested ensuring corresponding improvements in animal health with tsetse flies (Glossina spp.), which are the main problems, which are the principal causes of poor vectors for Trypanosoma. performance leading to an ever increasing gap between In Ethiopia, tsetse borne trypanosomiasis is possibly the supply and the demand for livestock products [1] the single most important disease, which excludes over Trypanosomosis is one of the world s most important 150, 000 to 00,000 km of fertile land in the west and diseases of livestock and man []. It is caused by southwest of the country from agricultural production. protozoan parasites of the genus Trypanosoma and is This area covers 15% of the total arable land [6]. arguably still the major constraint to livestock production Moreover [7] had indicated that there are frequent reports on the continent of Africa, preventing full utilization of of Trypanosomosis cases in Tsetse free areas of the land to feed the rapidly increasing human population [3]. country. There are six pathogenic species of Infection by one or other species of the trypanosomes in trypanosomes discovered in Ethiopia, namely Corresponding Author: Birhanu Hadush, Mekelle University, College of Veterinary Medicine, Ethiopia. Tel: +51-919-366578345741. 36

Trypanosoma (T.) vivax, T. congolense, T. brucei, T. evansi, T. equiperdum and T. rhodesiense. But the most important trypanosomes in the country are T. vivax and T. congelense. Both species affect a great number of cattle which are the most important species of the domestic animals in Ethiopia. Due to its extensive distribution, T. vivax is more important than T. congolense [6]. The impact of trypanosomosis on African agriculture is most obviously seen in the birth and mortality rates of young animals [8]. In susceptible cattle breeds, the disease reduces calving by up to 0% and causes the death of another 0% of young stock. Even the so-called trypanotolerant animals such as the N Dama cattle are affected. It strongly reduces milk off-take (reduction of 6%) and lambing and kidding rates (reduction of 37%) in the Gambia. Trypanosomosis reduces the availability and efficiency of drought animals used for preparing land for crop production (reduction of 33 %) in Ethiopia [9]. In mixed farming systems, where trypanosomosis is so severe that it constrains the number of oxen that farmers own, it can reduce the average area planted per household by as much as 50% [10]. Some 10-14 million heads of cattle in Ethiopia and an equivalent number of small ruminants together with a significant number of equines and camels are exposed to the risk of disease [11]. If trypanosomosis could be controlled in Ethiopia, much of the best-watered and most fertile lands of the southwest could be utilized [1]. Natural transmission of the African pathogenic trypanosomes has two phases; one in the insect vector or cyclical and the second is biting flies (non-cyclical or mechanical) transmission [13]. Biting flies of the genus Tabanus, Haematopta, Chrysops and Stomboxys transmit trypanosomes mechanically between vertebrate hosts. [15]. The importance of this mode of transmission is variable from place to place depending on the number of hosts and biting insects present and also the species of trypanosomes. Iatrogenic transmission is also possible which occurs when using the same needle or surgical, instruments on more than one animal at sufficiently short intervals that the blood on the material does not dry. This mode of transmission has proven to be sufficiently effective to maintain T. vivax and T.evansi [14]. Control and prevention of animal trypanosomosis is depends on the use of appropriate therapeutic/ prophylactic measures, control or elimination of tsetse vector flies. Treatment of trypanosomiasis frequently is complicated by developing drug resistance, toxicity and the damaging dermonecrosis produced by some of the trypanocidal agents [1]. The development of drug resistance against the trypanosomosis has been found increasingly in different countries of the world which is a serious problem to prevent and/or treat the disease [1, 17]. Only small groups of chemoprophylactic and chemotherapeutic trypanocidal compounds are currently in use and new compounds are unlikely to become available in the near future. It is estimated that in Africa 35 million doses of veterinary trypanocidal drug are administered each with isometamidium chloride (ISM), ethidium bromide (EtBr) and diminazene aceturate (DA) estimated to be represent 40%, 6% and 33%, respectively [18]. Although livestock trypanosomosis is a well-known constraint to livestock production in Ethiopia, most of the studies are conducted in south west, tse tse belt, region of the country and there is limited information in other part of the country (in tsetse free regions). Therefore, the objectives of this study were to assess the prevalence of mechanically transmitted trypanosomosis, particularly T. vivax infections of cattle in selected districts of Tigray region and document information on the management of suspected animals by professionals and farmers. MATERIALS AND METHODS Description of Study Area: Kafta Humera is about 560 km to the West of Mekelle, the Capital City of Tigray Regional State, with an altitude ranging from 580180 meters above sea level; and estimated population of 94,10. In the study district, there are 15 rural and two urban kebeles with a population of 70, 10 and 4,000 respectively, where households in rural kebeles are clustered in confined areas where as Yechila (Tanqua Abergelle) is located 110 km south west of Mekelle at 13.3 north latitude and 39 East longitude at an altitude of 1590 m.a.s.l. Average annual temperature ranges between 7 and 30 C, the vegetation of the area is dominated by xerophylic plants. But the other study area Ofla is one of the five rural woredas in South Zone of Tigray region that has 0 tabias/ 18 rural tabias & urban tabias. Its geographical location is in between 39 31 E longitude, 1 31 N latitude. It is bordered with Endamohoni woreda in the North, Raya Azebo woreda in the North East, Alamata woreda in the South East & Amhara region in the West. The woreda capital is called Korem & is located 17 km from regional capital. Its area is approximately 1086.55 sqkm or 133500 ha. The land use pattern of the woreda shows that 3000 ha is cultivated land, 17000 ha is covered with forest, 439 ha is covered with bush & shrubs (CSA, 007). 37

Sample Collection and Study Methodologies: The ear vein of the animal was disinfected by alcohol and pierced by individual sterile needles/ blood lancets and blood sample was collected into Heparinized microhaematocrit capillary tubes (up to ¾ of their height). The capillary tubes were sealed at one end with crystal sealer and placed in pre-labeled modified capillary tube racks. Samples were transported to temporary resting sites where they were centrifuged in a Microhematocrit centrifuge for 5 minutes at 1000 rpm. After centrifugation, the packed cell volume (PCV) was determined by placing on Haematocrit reader as described in [3]. As indicated in [19], a PCV measurement of 5% was regarded as a threshold value. Animals with a PCV = 5% were considered to be anemic. The PCV level of each animal was recorded and buffy coat smear was prepared on microscopic glass slide by breaking the capillary tubes. The thin blood smears of buffy coat samples were fixed by methanol for 5 minutes, stained with Giemsa staining and examined under a light microscope using x100 oil immersion objective lens. Identification of the parasite was made by observing the structure of the parasite as indicated in [0]. Questionnaire Survey: Structured questioner format was used to interview farmers in order to acquire base line information about Trypanosomosis and its management. 45 farmers form Kafta Humera district and 80 farmers form Ofla district were included for questionnaire survey. The questions addressed to farmers contained about knowledge of trypanosomosis /slim/, species of animals frequently affected, the main clinically signs /symptoms of diseased animals and management/treatment options used by the farmers if they encounter sick animals. The sources of drugs used to treat their animals and any information related to the cause and seasonal of occurrence in the area. Data Entry and Analysis: Individual data were entered on prepared excel sheet format and coded appropriately. SPSS version17 statistical software was used for data analysis. Proportions were used to indicate the percentages of the occurrence of the disease and Chisquare (X ) test was used to see the association of the disease with different variables (age, sex and % PCV). RESULTS Parasitological Findings: From a total of 397 cattle examined in this study, n=35 (8.8%) of them were infected with T. vivax. The occurrence of T. vivax infection was Table 1: Prevalence of T. vivax infection in bovine among different risk factors No. animal Number of positive Risk factors examined animals (%) P - value District 0.051 Kafta-Humera 34 18 (7.7%) Ofla 163 17 (10.4%) Total 397 35 (8.8%) Sex 0.903 Female 80 5 (8.9%) Male 117 10 (8.5%) Total 397 35 (8.8%) Age (in year) 0.044 Less than 5 178 1 (6.7%) 5 10 180 1 (11.7%) Greater than 10 39 (5.1%) Total 397 35 (8.8%) Table : Frequency distribution of PCV values with regard to the threshold value (5%) bovine among different risk factors No.(%) of animals with PCV value No. animal ------------------------------------------- Risk factors examined Less than 5 Greater than 5 P - value District 0.050 Kafta-Humera 34 67 (8.6%) 167 (71.4%) Ofla 163 6 (38.0%) 101 (6.0%) Total 397 19 (3.5%) 68 (67.5%) Age (in year) 0.03 Less than 5 178 117 (65.7%) 61 (34.3%) 5 10 180 11 (6.1%) 169 (93.9%) Greater than 10 39 1 (.6%) 38 (97.4%) Total 397 19 (3.5%) 68 (67.5%) Sex 0.046 Female 80 47 (16.8%) 33 (83.%) Male 117 8 (70.1%) 35 (9.9%) Total 397 19 (3.5%) 68 (67.5%) Infection status 0.05 Parasitemic 35 4 (68.6%) 11 (31.4%) Aparasitemic 36 105 (9.0%) 57 (71.0%) Total 19 (3.5%) 68 (67.5%) higher in Ofla district (10.4%) than Kafta-Humera district (7.7%), however this variation was not statistically significant (p-value = 0.051). There was no difference in the occurrence of T. vivax infection between females (8.9%) and males (8.5%) with P-value of 0.903. The prevalence of T. vivax infection was higher in cattle with age group of 5 10 years (11.7%) than other age groups and this was statistically significant (p-value = 0.044) (Table 1). Haematology: In this study, to assess the effect of T. vivax infection on a PCV measurement we use a threshold value of 5%. The number of animal with PCV value less than 5% was higher in Ofla (38.0%) than 38

Kafta-Humera (8.6%) district and had no significant dissolve one sachet of Diminazene aceturate. With regard difference (p-value =0.050). In addition, 65.7% the animals to the seasonal disease distribution, 57.16% of the with the age group of less than 5 years had a PCV value respondents said the disease is common at any less than 5% compared to the other age groups and this season while the rest 19.04% and 3.8% respondents was statistically significant (p-value = 0.03). Similarly, said that it is common at the end of rainy season and in most (70.1%) of male had PCV below 5% than female drought/dry season, respectively. For the cause and (16.8%). The number of parasitaemic animals (68.6%) with transmission of the disease, of the respondent said that PCV value below 5% was higher than aparasitaemic the disease is transmitted/caused by drinking of animals (9.0%). However, there was no significant contaminated water (57.%) and fly bite (14.8%) while difference in the prevalence of trypanosomosis between the rest 8.5% said that it mainly associated with drought parasitaemic and aparasitaemic animals (p-value = 0.05) seasons. (Table ). Woreda Ofla: Of the 80 interviewed farmers 98.7% (75/76) Questionnaire Survey Results of them reported that the disease was known in the study Kafta Humera District: The result obtained from area for many years and still considered as an important questionnaire survey showed that the most predominant and first priority disease. In this long period of time, species affected by the disease are cattle with response trypanosomosis hampered animal production and rate of 76.19%, followed by goat, sheep and equine with productivity and resulted considerable socio economic the response rate of (4.76%). Moreover, almost all losses through mortality and morbidity of drought power respondents indicated that the infection is more common animals in particular and other animals in general. All in adult animals while 83.3% respondents also said it is farmers indicated that they don t administer any common in young animals. According to the respondent, trypanocidal drug by themselves when they suspected a the clinical signs manifested by Trypanosomosis sick clinical case and take the animals to nearby veterinary animals include emaciation (50%), rough hair coat (55.1%), clinicians. However, 81.6% (6/76) of the farmers reducing milk yield (14.8 %) and diarrhoea (54.76%). underlined that there is shortage of availability of When the animal owners got a suspected cases of Trypanocidal drugs and professionals in their nearby Trypanosomosis (slim locally) about 77.7% of veterinary posts. Though small in number, 100% of respondents agreed that they treat the animals by professional respondents indicated that they can themselves while.3 % took their animals to nearby tentatively diagnose the disease and were treating the veterinary clinic. disease for the last 10 years with veriben and diminazene The interviewed farmers described that the reason to aceturate. treat their animals by themselves were the absence of veterinary service in their locality (5.38%), limited access DISCUSSION /long distance/ (16.6%), poor veterinary service (14.8%) and aggressive behaviour of animals to veterinary In this study the observed prevalence (8.8%) professionals/ guests (4.76%). The sources of suggests that trypanosomosis is an important diseases of trypanocidal drugs were from private pharmacy (71.4%), cattle in the study areas. The current study was governmental clinic (8.57%), illegal market /shop conducted during the long dry season and the prevalence (14.8%) and from both government and private pharmacy of the disease in the study areas can increase more than (4.76%). The respondent indicated that, dimenzene the obtained result as the prevalence of trypanosomosis acturate and homodium chloride /Ethidium tablet/ are the infection decreases substantially during the long dry main trypanocidal drugs used to treat their animals. season and remained high during the early dry season Although the farmers don t know the name of drugs but (end of rainy season) [1]. they differentiate by the colour and by the form of the The observed 8.8% % prevalence of T. vivax drugs just like saying, yellow sachet for diamenzene infection in this study was lower as compared with the aceturate and red tablet for homodium chloride. Even previous 14% report of Langridge [] in south west part though all respondent know the route of administration, of Ethiopia. This could be due to the variation in they do not use the appropriate doses and preparation of availability of suitable vectors, season of the study and the drugs. Instead of the recommended 1.5 ml saline diagnostic tools utilized. Desalegn, Etsay and Getachew water, they used 10 ml of boiled and cooled tap water to [3] stated that the prevalence of trypanosomosis 39

infection decreases substantially during the long dry The experience of the farmers about trypanosomosis season and remained high during the early dry season was in agreement with the previous report [3]. Absence (end of rainy season). Indicating that, the prevalence of T. of veterinary service in their locality, limited access /long vivax infection in this study area could be higher than the distance/ to veterinary clinics, poor veterinary service, obtained result (since it was conducted during the long insufficient availability of trypanocidal drugs in dry season). Moreover, the unethical use of trypanocidal government veterinary clinics and limited diagnostic drugs existing in Kafta Humera could reduce the facilities were among the major problems, not to treat the parasitemic level there by unable to be diagnosed by disease, listed by the respondent. In addition, all the parasitological techniques. professionals interviewed in this study reported that they There was no statistically significant difference never confirmed this disease by laboratory diagnostic (P value = 0.051) in the prevalence of the disease between method and they simply make tentative diagnosis by its Kafta-Humera and Ofla districts, which might be due to clinical signs and its respond to trypanocidal drugs. This the similarity of their agro ecology and animal husbandry can create in misuse of Trypanocidal drugs which might system. There was also no statistical significant (P value end up in failure in therapeutic response. These all factors = 0.903) in the prevalence of the disease between male and together with the use of trypanocidal drugs from illegal female cattle. This might be due to the presence of similar market /shop by the farmers can be a predisposing factor husbandry system which exposed the animals equally to for the development of Trypanocidal drug resistance. the field infection in the study area. The prevalence of T. More over the long time usage of a single trypanocidal vivax infection in animals with the age group of 5-10 years drugs was higher (11.7%) than the rest category. This could be explained by the fact that, the cumulative effect of CONCLUSION repeated exposure to the mechanical vectors for longer time could increase the prevalence of the disease in older In general, the present study demonstrated that animal than younger animals. trypanosomosis is becoming a serious problem to In the current finding, there was no statistical livestock production in the study areas. However, it significant association in the level of anaemia between the seems that the low quality of veterinary service may lead two districts and the status of the infection. Even though to failure of treatment and the development of drug animals with the age group of 5-10 years were more resistant strains of T. vivax. As a result the animal affected by the disease, most of the animals (65.7%) with production will be reduced due to mortality and morbidity the age group of less than 5 years had a mean PCV value there by seriously affecting the crop production. Thus, of less than 5 and this was statistically significant attention should be given to improve the veterinary difference (Pvalue = 0.03). 70.1% of male animals had a service delivery both in quality and quantity of facilities, mean PCV value of less than 5. This was also statistically accessibility and affordability. Legislative and strict significant difference (Pvalue = 0.046). These all supervision should be implemented to solve the variations in the level of PCV value and the occurrence of indiscriminate usage of drug around the study areas and the disease among the different risk factors affected by awareness should be given to farmers about the feature many factors. As indicated by Murray, Murray and implications of indiscriminate drug use. Further study on McIntyre [3], the observation of parasitological negative seasonal dynamicity of the disease, characterization of the animals with a PCV values of less than the threshold value strains and drug resistance will give better picture of the set (5%) may be due to the inadequacy of the detection disease. method used, or delayed recovery of the anaemic situation after current treatment with trypanocidal drugs. REFERENCES Also the occurrence of positive animals with PCV value of greater than 5% might be thought of recent infections of 1. Taffese, A. and K. Mekonnen, 1998. The Role of the animals. Hence, the mean PCV value could better be Traditional Veterinary Herbal Medicine and its an indicator of the health status of cattle population under constraints in the animal health care system in study. It was generally accepted that mean PCV value was Ethiopia, Proceeding of the national work shop on affected by many factors other than trypanosomosis. Biodiversity, Addis Ababa, Ethiopia, Pp. -8. However, these factors are likely to affect both. st Levine, N.D., 1985.Veterinary Protozology. 1 Ed., trypanosomosis positive and negative animals [5]. Iowa State University Press. Ames. Iowa. 40

3. Murray, M., P.K. Murray and W.I.M. McIntyre, 1977. 14. Uilenberg, G., 1998. A filed guide for the diagnosis, An improved parasitological Technique for the diagnosis of African trypanosomosis. Trans. R. Soc. Trop. Med. Hyg. 71:35-36. treatment and prevention of African animal 4. Ford, J., 1971. The Role of Trypanosomiasis and Tsetse Flies in African Ecology. A Study of the Tsetse Fly Problem. Oxford University press. 5. Mattioli, R.C., U. Feldmann, G. Hendrickx, W.Wint, J.Jannin and J. Slingenbergh, 004. Tsetse and trypanosomiasis intervention policies supporting sustainable animal-agricultural development, Food, Agriculture & Environment (): 310-314. 6. Dagnatchew, Z., 198. Proceedings of the 3 rd International Symposium on Veterinary Epidemiology and Economics. Available at www.sciquest.org.nz, Pp: 467-473.http//microbeuiki, Kenyon edu/php/ trypanosome and life cycle of Tryanosoma 7. Mihretu, A. and G. Mamo, 007. Bovine Trypanosomosis in Three districts of East Gojjam Zone bordering the Blue Nile River in Ethiopia, J Infect Developing Countries 1(3): 31-35 8. Erkelens, A.M., R.H. Dwinger, B. Bedane, J. H.W. Slingenbergh and W. Wint, 000. Selection of Priority Areas for Tsetse Control in Africa; a Decision Tool Using GISin Didessa Valley, Ethiopia, as a Pilot Study. In, Animal Trypanosomosis: Diagnosis and Epidemiology. FAO/IAEA Coordinated Research Programme on the Use of Immunoassay Methods for Improved Diagnosis of Trypanosomosis and Monitoring Tsetse and Trypanosomosis Control Programmes. International Atomic Energy Agency, Vienna, Austria. 9. FAO, 1998. Cost of Trypanosomosis, Spotlight. Food and Agriculture Organization of the United Nations, Magazine Agriculture 1: 1-. 10. FAO, 000. Impacts of Trypanosomiasis on African Agriculture, by B.M. Swallow. PAAT Technical and Scientific Series No.. FAO, Rome pp. 5. 11. Ministry of Agriculture (MOA), 1996. Ruminant Livestock Development Strategy (RLDS), Addis Ababa, Ethiopia, Pp. 5-30. 1. Chaka, H. and G. Abebe, 003. Drug resistant trypanosomes: a threat to cattle production in the Southwest of Ethiopia. Revue d Elevage et de Médecine Vétérinaire des Pays Tropicaux, 56(1-): 33-36. 13. Urquhart, G.M., J.Armour., J.L. Duncan, A.M. Dunn and F.W. Jennings, 003. Veterinary parasitology, Blackwell publishing, UK. pp: 09-18. trypanosomosis. Rome, FAO, UN. pp: 450-470. 15. Leak, S.G.A., 1999. Tsetse biology and ecology; their epidemiology and control of Trypanosomosis, CABIpublishing in association with the ILRI, pp: 15-10. 16. Eisler, M.C., R.H. Dwinger, P.A.O. Majiwa and K. Picozzi, 004. Diagnosis and Epidemiology of African Animal Trypanosomiasis. The Trypanosomiases. CAB International. CABI Publishing Wallingford, UK. pp: 53-67. 17. Delespaux V., H. Dinka, J. Masumu, P. Van den Bossche and S. Geerts, 008. Five-fold increase in Trypanosoma congolense isolates resistant to diminazene aceturate over a seven-year period in Eastern Zambia. Drug Resist. Updat., 11(6): 05-09. 18. Delespaux, V. and H.P. De Koning, 007. Drugs and drug resistance in African trypanosomiasis, Drug Resist. Updat., 10: 30-50. 19. Jemere, B., 004. Control of tsetse and trypanosomosis in the Southern Rift Valley (STEP area): evaluation of deltamethrin applications, Msc thesis, AAU School of Veterinary Medicine, Debrezeit-Ethiopia. pp: 50-60. 0. Rosaosorio, A.L.A., C.R. Madruga, M. Desquesnes, O.C. Soares, L.R.R. Riberio, da S.C.G. Costa, 008. Trypanosoma (Dutennela Vivax): It s Biology, Epidemiology, Pathogenesis and introduction in the new world a review. Mem InstOswaldo Cruz Rio de Janeiro, 103(1): 1-13. 1. Abebe, G. and Y. Jobre, 1996. Trypanosomosis: A threat to cattle production. Rev. Vet., 147: 897-90.. Langridge, W.P., 1976. A Tsetse and Trypanosomiasis Survey in Ethiopia. Ministry of Agriculture, Ethiopia and Ministry of Overseas Development, United Kingdom. 3. Desalegn, W., K. Etsay and A. Getachew, 010. Study on the assessment of drug resistance on Trypanosoma Vivax in Tselemti wereda, Tigray, Ethiopia. Ethio. Vet. J., 14 (1): 15. 4. Radostitis, O.M., C.C. Gay, D.C. Blood and K.W. Hnchcliff, 000. Veterinary Medicine, A Text book of Diseases of cattle, sheep, pig, goat and th horse. 9 Ed. Harcourt Pub. Ltd.London. 5. Van den Bossche, P. and G.J. Rowlands, 001. The relationship between the parasitological prevalence of trypanosomal infections in cattle and herd average packed cell volume. Acta Trop., 78: 163-170. 6. Ayledo, G., 008. Studies on bovine trypanosomosis and efficacy of selected trypanocidal drugs in Konso district, Southern Ethiopia, Msc thesis, AAU, School of Veterinary Medicine, Debrezeit Ethiopia 41