Prevalence of Ovine Lung Worms- Around Bahir Dar, East Africa, Ethiopia

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1 ISSN IDOSI Publications, 013 DOI: /idosi.apg Prevalence of Ovine Lung Worms- Around Bahir Dar, East Africa, Eiopia Kassa Tamire and Abdu Mohamed University College of Agriculture and Veterinary Medicine School of Veterinary Medicine, P.O. Box: 307 Jimma, Eiopia Abstract: A cross sectional study was conducted in and around Bahir Dar from October, 011 to March, 01 wi e aim of determining e prevalence of ovine lungworm infection, to assess associated risk factors and to identify lungworm species involved in e area. In is study a total of 456 feacal samples from sheep of all age groups, management, body condition score and bo sexes were examined using modified Baerman technique to extract L1 larvae. The finding indicated at 9(0.%) were found infected wi different species of lungworms namely; D. filaria (11.%), M. capillaries (6.1%) and P. rufescens (0.7%). Mixed infection was observed in.% of e cases. There was a significant difference (P=0.04) in e prevalence of lungworm infection wi regard to sex (female 4.5% and male 13.4%), management system (extensive 0.9% and semiintensive 9.7%). The prevalence of lung worm in different age groups (<1year 3.7%, 1-3years 6.4% and > 3years 9.5%) and body conditions (poor 4%, medium 19.8% and good 19.6%) was not statistically significant (P>0.05).In is study younger sheep were found more affected widictyocaulus filaria(d. filaria), while older once were more infested wi Muellerius capillaries (M.capillaries). Additionally 00 sheep from Bahir Dar Municipal abattoir and private hotel Azewa,were examined postmortem and 11(60.5%) were found to harbor different species of lungworms. The overall prevalence of ovine lungworm infection was found to be higher in postmortem (60.5%) an coproscopic examination (0.%). It can be summarized at e high prevalence of Verminous pneumonia was as e result of e ree lung worm species. Finally possible control measures of e disease are forwarded. Key words: Bahir Dar Dictyocaulus filarial Lungworm Muellerius capillaries Protostrongy lusrufescens Prevalence Ovine INTRODUCTION huge number [1]. This low productivity is a reflection of disease, limited genetic potential and husbandry standard. Eiopia is a leading African country in livestock The morbidity of animals generally estimated to be in e population and ranks 9 in e world [1]. The livestock range of 8-10% of national cattle herd per annum and subsector accounts for about 40% of e agricultural 14-16% and 11-13% of national sheep and goat flock per Gross domestic product (GDP)and 0% of e total GDP annum. respectively wi average live weight loss of 70kg [] wiout considering e contribution livestock in terms for cattle and 6kg for sheep and goat. The national value of draught power, manure and transport services. of is direct loss is estimated to be of 550 million Excluding exports of live animals and oer products, Eiopian birr [5]. leaery and leaer products alone contribute 18% of e Helmines of ruminants are ubiquitous and prevalent total exports [3]. wi many tropical and sub tropical environments of e In Eiopia livestock population (in millions) is world providing nearly perfect conditions for eir estimated at 44.3 cattle, 3.6 sheep, 3.3 goats,.3 camels, survival and development [6]. Diseases of respiratory 6.1 equines (donkeys, horses and, mules) and 4.9 system are some of e leading cause of morbidity and chickens [4]. However e economic gains from ese mortality in sheep and major source of economic losses animals remain insignificant when it is compared to eir [7], among ese e common infections of lung of Corresponding Auor: Abdu Mohamed, Jimma University College of Agriculture and Veterinary Medicine School of Veterinary Medicine, P.O. Box: 307 Jimma, Eiopia. 71

2 sheep is lung worms. These are D. filaria, M. capillaries and P. rufescens. Alough mixed infections can occur [8, 9]. The signs of lung worm infection (Varminouspneumonia), range from moderate coughing wi slightly increased respiratory rates to sever persistent coughing [9]. Dyspnea, nasal discharge, weight loss, in case of associated bronchopneumonia also reveals dea [9-11]. Control of ese parasites is essential, for releasing e potential of sheep production. For proper control e knowledge of parasitic diseases and rules for eir control must be applicable to all regions. For is reason a study of epidemiology of each parasitic disease should not be limited to small areas [1]. In Bahir Dar different researches conducted by Sisay [13] and Muluken [14] in relation to ovine lung worm infection who reported 13% and 18.5% respectively. But e incidence of lung worm varies greatly from place to place and time to time depending on e relative importance of many of e factors. In order to investigate a sound lung worm control strategy at local and regional level furer and detailed investigation on epidemiology and importance of lung worm infections wi respect to its temporal distribution is necessary. Therefore, e objectives of is study were: To determine e prevalence of lung worm infection in sheep. To identify lung worm species ose are involved in e area. To assess major risk factors associated wi e disease. MATERIALS AND METHODS Study Area: The study was conducted in and around Bahir Dar. Bahir Dar is e capital city of Amhara Regional State and located at 11 9 N latitude, 37 9 E longitude at about 570km Nor-West of Addis Abeba. The area has middle altitude ranges from meters above sea level which is called Woyenadega. The area receives a bimodal rainfall wi an average annual rain fall ranges from mm. The mean annual temperature of e study area is 3 C. The presence of e biggest Lake Tana and River Abay influence e climatic condition of e study area. The area has a mixed farming practice wi crop and livestock production. According to e census at was made by CSA(4), ere are 158,564 cattle, 18,87 sheep and goats, 8,000 equine and 366,666 poultry in and around Bahir Dar. Study Population: The study population was all sheep at were found in and around Bahir Dar town. The total of 456 sheep of indigenous breed of different sex, age, body condition and different management conditions were selected and of which 77 of em females and 179 were male sheep. From e total study population 45 sheep were selected from extensive farms while e rest 31 sheep were from semi - intensive farms at were selected randomly by eir percentage proportion from e total population of sheep. Study Design and Sampling Techniques: The study was cross-sectional wi simple random sampling technique to determine e prevalence of ovine lung worm infection in and around Bahir Dar. A total of 456 sheep were randomly selected from each Kebeles at are found in and around Bahir Dar. Coprologicalfaecal examination of faecal samples was used to determine e prevalence of lung worn invasion in study area. In addition, e lungs of two hundred sheep at were slaughtered at Bahir Dar Municipal Abattoir and in one private hotel named Azewa were examined post mortem procedure to determine e prevalence of adult lung worm infection. Sample Size Determination: The study was conducted from October 011 to March 01 in and around Bahir Dar. The sample size required for is study was determined depending on e expected prevalence of lung worm invasion and e desired absolute precision. The sample size was computed using e formula given bythrutfield (15) as follows Pexp (1-Pexp) N = d where: N = required sample size; P exp = expected prevalence; d= desired absolute precision. Previous studies at were conducted on prevalence of lung worm in sheep in e study area show 18.16% of prevalence rate. Therefore, an expected prevalence of 18.16% was used to estimate e sample size. Using desired 95% confidence interval, 5% precision and 18.16% expected prevalence, e number of sheep needed to determine e prevalence lung worm in study area were 8 sheep. However, to increase e level of precision e number of sheep was doubled and 456 sheep were sampled. In addition, a total of 00 sheep lungs were also examined by post mortem examination to see e presence of adult parasites. 7

3 Study Meodology nature and e characteristics of data. The prevalence of Coprological Examination lung worm infection was analyzed using percentages. Sample Collection: Total of 456 faecal samples were The association of different risk factors wi e disease collected in universal bottles and transported to e was computed by Chi - square ( ) test. Regional Veterinary laboratory as soon as possible. Faecal samples were collected directly from rectum by RESULTS two fingers after wearing disposable gloves. All samples were clearly labeled wi e date of sampling, sex, age, Coprological Examination body condition score and e management system at Overall Prevalence of Lung Worm: Of a total 456 faecal was used. The age of animals was gaered from e sample of sheep at were examined 9 (0.%) were owners and dentations. found to be infected wi eier one or more of e lung worm species. Laboratory Technique: Using Baermantechnique Twenty five grams of fresh faeces was weighed from each sample. Species Identification: The prevalence rate of species The larvae and enclosed gauze fixed on to astring rode of lung worm in sheep in e study area was different was submersed in a clean glass tube which was filled wi and mixed infestation of two or more species of lung warm water left for 4 hours and e sediment was worm were observed. Therefore, e prevalence rate of examined under lower power of microscope after D. filaria, M. capillaries, mixed infestation and siphoning off e supernatant. Finally a drop of 1% iodine P. rufescens was 11.%, 6.1%,.% and 0.7% respectively. solution was added to e slide to immobilize e larvae as There was highly statistically significant difference soon as e larvae are detected under microscope. to (P< 0. 05). Theprevalence of different species of lung identify e species of e larvae. If not identified under worm in e study area are as indicated on (Table 1). microscope, e examined samples were registered as negative for lung worm infection. In bo cases, e result Prevalence of Ovine Lung Worm in Different Sex and at was obtained for each sample was recorded to eir Age Groups: An attempt was made to see if ere was corresponding specific animal [16, 17]. difference in prevalence rate of lung worm between sex groups. The result indicated at ere was difference in Post Mortem Examination: The lungs of sheep at were isolation rate of lung worm between sex groups wi slaughtered at Bahir Dar municipal abattoir and in Azewa prevalence rate of 4.5% in female and 13.4% in male private hotel were examined for lung worm infection were sheep. The association of e prevalence rate of lung digitally palpated to diagnose e presence of worm wi sex was computed wi Chi-square test. protostrongylidea nodules on affected lung tissues. There was statistically significant difference (P<0.05) And e nodules were trimmed off and e adult worms between e prevalence rate of lung worm and sex groups were extracted from e tissues by gentle comprising of a in sheep as indicated on (Table ). small non-calcified nodules or part of large nodule using Similarly to sex e influence and association of age two glass slides and were carefully tested. on e prevalence rate of lung worm infection was In addition, air passages were opened starting determined and it was found at ere was difference in from e trachea down to e small bronchi wi fine e prevalence rate of lung worm infection between age blunt pointed scissors to detect e adult parasites. groups. It was 3.7% in sheep less an 1year, 6.4% in All visible adult worms from affected lung tissues were sheep 1-3 years and 9.5% in sheep greater an 3 years. carefully removed and transferred to glass beakers There was statistically significant difference (P=0.04) containing 10% formalin and were identified up to species between e prevalence rate of lung worm and age groups level [1, 16]. as indicated on (Table 3). The prevalence rate of different lung worm species Data Management and Analysis: The data were entered at were isolated from different age groups was different and managed in MS -Excel. All e data analysis was done wi different age groups and ere was highly by Statistical Package for Social Science (SPSS) soft ware statistically significant difference (P= 0.001) between e version 16. Descriptive statistics such as percentages isolation rates of different species of lung worm wi age and frequency distributions were used to describe e groups as indicated on (Table 4). 73

4 Table 1: Prevalence of e ovine lung worm infection wi species variation Lungworm spp. Positive 95% CI Prevalence (%) - value P value D. filaria M. capillaries Mixed Infection P. rufescens Total Table : Prevalence of lung worm infection wi sex variation Sex Sheep examined Sheep infected Prevalence (%) 95% CI -value P-value Female Male Total Table 3: Prevalence of lung worm infection wi age variation Age Sheep examined Sheep infected Prevalence (%) 95% CI -value P-value <1year years >3years Total Table 4: Prevalence of different species of lung worm wi age and eir association wi different age groups Identified species of lung worms Age Sheep examind D. filaria M. capilaries P. rufescns Mixed -value P-value <1year (0.1%) 4(.1%) 0(0%) 3(1.5%) years 15 7(5.6%) 17(13.6%) 1(1.6%) 7(5.6%) >3years 137 5(3.65%) (5.1%) 1(0.73%) 0(0%) Table 5: Prevalence of lung worm infection and its association wi different management systems Management systems Sheep examind Sheep infected Prevalence (%) 95% CI -value P-value Extensive Semi-intensive Total Table 6: Prevalence of ovine lung worm infection in different body conditions and its association wi different body condition scores BCS Sheep examined Sheep infected Prevalence (%) 95% CI - value P-value Poor Medium Good Total Table 7: Prevalence of adult lung worm burden wi species during postmortem examination of lung Lungworm spp. Lung examined Lung infected Prevalence (%) 95% CI D. filaria M. capilaries P. rufescens Total Table 8: Coproscopic and Post mortem examination results of lung worm Type of examination Examined Positive Prevalence (%) 95% CI Coproscopic Postmortem

5 Prevalence of Ovine Lung Worm under Different e disease exposed e animals to secondary bacterial Management Systems: In is study e prevalence infections. It also causes an economic loss due to organ of lung worm was determined in sheep at were reared condemnation and medication costs. in two different management systems (extensive and semi In is study, attempts were conducted to know e - intensive management systems) and e prevalence of prevalence of lung worm infection in and around Bahir lung worm was found to be higher in sheep wi e Dar. Coprological examination of faecal samples and extensive management system (0.9%) as compared to e postmortem examination of lungs were used to determine semi-intensive management system (9.7%). However, e overall prevalence of lung worm in e study area. ere was no statistically significant difference (P>0.05) Coprological examination of faecal samples revealed between e prevalence of lung worm infection of sheep 0.% of overall prevalence of lung worm infection in e in e two management systems as indicated on (Table 5). study area. Almost similar results were reported previously by Muluken [14] in Bahir Dar, Mengestom [18] Prevalence of Ovine Lung Worm Infection in Different in Atsbi and Dawit and Abdu (19) in Jimma who reported Body Conditions of Animals: All sheep at were e prevalence of lung worm infection 18.16%, 1.5% and examined for lung worm infection were categorized in to 5.6% respectively. The isolated parasites were identified ree groups as poor, medium and good body condition. up to species level and D. filaria, M. capillaries and It was observed at e prevalence of lung worm P. rufescens were emajor respiratory nematodes of infection was 4%, 19.8% and 19.6% in sheep wi poor, sheep in e study area. However e current prevalence medium and good body conditions respectively. There of lung worm is lower an e prevalence at was was no statistically significance difference (P> 0.05) reported by Netsanet [0] in Debrebirhan, Alemu [1] in between e prevalence rates of lung worm infection in Nor West Eiopia, Mezgebu [] in Addis Ababa and different body conditions as indicates on (Table 6). Mihreteab and Aman [3] in Tiyo wi e prevalence of 73.5%, 53.6%, 48% and 57.1% respectively. The present Postmortem Examination finding is higher an e prevalence of lung worm at Over All Prevalence of Lung Worm: From e total sheep was reported by Teffera [4] in Dessie and Kombolcha, at were slaughtered in Bahir Dar Municipal Abattoir and Frewengel [5] in Tigray and Sisay [13] in Bahirdar wi private hotel Azewa during e study period two prevalence of 15.47%, 11.4% and 13% respectively. hundred sheep lungs were randomly selected and These differences in e prevalence might be associated examined by post mortem procedure to investigate e wi e variations in agro-ecology of e study areas adult parasite of lung worm. The result showed at e which favor e survival of parasites larvae in general overall prevalence of adult lung worm infection was found and/or e presence or absence of snail intermediate host to be 60.5%. Then e adult parasites were identified up to in case of P. rufescens; biological difference of e species level and ree species of lung worms D. filaria, hostand e seasonal variation when samples were P. rufescens and M. capilaries were identified wi collected. prevalence rate of 17.5%, 14% and 9% respectively Moreover, according to Bradford [6] and Soulsby (Table 7). [7] e occurrence of lungworms is associated wi nutritional status, level of immunity, management practice Coproscopic and Post Mortem Examination Results of of e area, rain fall, humidity and temperature and Ovine Lung Worm Infection: Comparison of e overall seasonal differences when e sample were collected for prevalence of ovine lung worm infection was found to be examination in e respective study areas. higher in postmortem examination (60.5%) an Wi regard to e species of lungworms, D. filaria, Coproscopic examination 0. % as indicated on (Table 8). M. capillaries and P. rufescenswere emajor species of lung worms at were identified in e study area and DISCUSSION D. filarial was e predominant species followed by M. capillaries, mixed infection and P. rufescenswi Lung worm infection (Verminous bronchitis, prevalence of11.%, 6.1%,.% and 0.7% respectively, Verminous pneumonia) is a chronic and prolonged which was in total agreement wi e work of Alemu (1); nematodosis at affects e lungs of sheep and goats. Netsanet [0]; Nemat and Moghadam [8]. The difference This disease results in substantial economic losses due to was highly statistically significant (P< 0.05). This could be e reduction of grow rate, morbidity and mortality as due to e fact at e parasites have different life cycles. 75

6 Since D. filarial has a direct life cycle and requires shorter indirect life cycle; takes longer time to reach e infective time to develop to an infective stage (larvae of ese stage and after ingestion; e larvae can appear in faeces parasites can be shed wi faces wiin 5 weeks [7], it is after several weeks. The oer reason is at e e most predominate species of lung worm in e probability of infection, transmission and re- infection study area. Compared wi D. filarial, e transmission of wi in a season would be much lower as compared wi P. rufescens and M. capillaries is epidemiologically D. filaria. This factor might be why young animals have complex and requires host, parasite and intermediate host low infection rate ofm.capilaries infection [18]. relationship. That is why eir prevalence is lower in e In is study, an attempt was conducted to know if study area. ere is difference in prevalence of ovine lung worm In is study, attempts were conducted to know if infection under different management systems. It was ere is variation in lung worm infection between different found at e overall Prevalence of ovine lungworm sex groups. The study showed e prevalence of lung infection was 0.9% and 9.7% in extensive and semiworm infection was 4.5% in females and 13.4% in males. intensive management systems respectively. The The difference was statistically significant (P<0.05). difference was not statistically significant (P > 0.05). This could be due to e fact at e hosts have different This could be due to e fact at animals under resistance to infection which may be decreased in females semi-intensive have a chance of grazing in e field, at e time of parturition and during early lactation. exposure to e intermediate host (snail or slugs) or That is why lung worm infection is more prevalent in directly can be infected wi lung worm while ey are females an males which were in total agreement wi e grazing in e grazing field. This finding disagrees wi work of Sissay [13] and Sefinew [30]. e finding at was reported by Dawit [35] in Tse-Ada- In relation to e age of animals, e prevalence of Emba; wi e prevalence of 30.43% and 5% in extensive lung worm infection was varied wi age of animals and it and semi - intensive farms respectively. was found to be 3.7%, 6.4 % and 9.5% in sheep wi e This could be due to e difference in agro-ecology age of less an one year; 1-3 years and greater an 3 and season of e two study areas; sampling and years respectively. The difference was statistically sampling techniques at are used and it may be due to significant (P< 0.05). e differences in breed and e biology of animals. This could be due to e fact at e acquired Inis study, anoer attempt was conducted to know immunity at developed in older animals due to previous if body condition has influence on prevalence of ovine exposure and sheep at recovered from e infection lung worm infection; and it was found at e prevalence have better immunity against re-infection [31, 3]. of ovine lung worm infection was 4%, 19.6% and 19.8% However is study contradicts when we look in e case in sheep wi poor, good and medium body condition of sheep wi e age of less an 1 year (3.7%) and score respectively. There was no statistically significant young sheep wi e age of 1-3 years (6.4%). This is difference (P >0.05) which was in total agreement wi e because young sheep wi e age of less an one year work of Thomson and Orita [36]. The possible explanation (mostly lambs) are not allowed for free grazing in order to for question; why do sheep wi poor body condition prevent e lamb from e predator. That is why even if more affected by lung worm? It could be due to e immunity of lamb is not well developed, e immuno-suppression in sheep wi poor body conditions, prevalence of lung worm infection is less an young concurrent infection by oer parasites including GIT sheep, which was in total agreement wi e work of helmines and/or malnutrition [37]. Poorly nourished Uqbazghi (9) and Wondowossen [33] who reported at sheep appear to be less competent in getting rid of young sheep were found to harbor as many lungworms as lungworm infection [38, 11]. Evidently, infestation wi e compared wi adult sheep. parasite by itself might result in progressive emaciation of In is study Young sheep < 1year were found to be e animals.however is result disagrees wi e report more affected to lung worm species of D. filaria. of Dawit and Abdu [19] in Jimma who reported e This finding agrees wi e finding of Uqbazghi (9) prevalence of ovine lung worm in poor (6.8%) medium in Hamasein Who reported younger animals of sheep was (5.6%) and good (8.3%) body condition and were not found to be more susceptible to D. filarial while older statistically in significant difference (P >0.05). The once were more infested wi M capilaries. The same difference in prevalence of ovine lung worm infection finding was also reported by Teffera [4] in Dessie and between e two studies in ree body condition scores Kombolcha and Sisay [7] in Bahir Dar. The reason why is may be due to differences in breed, study areas, adults are more affected by M. capilaries is at it has antihelmentic drug applications and management systems. 76

7 In addition to coprological examination, affected by M. capilaries. The prevalence of lung worm postmortemexamination of e lungs of sheep at were infection has significant association wi sex and age in slaughtered in Bahir Dar Municipal Abattoir and private e study area. The economic implication of e disease hotel; Azewa was performed to know e prevalence seems very huge. In view of ese facts e of ovine lung worm infection in and around Bahir Dar. followingrecommendations are forwarded. The result revealed at e overall prevalence of lung worm infection to be 60.5%. The overall prevalence of Regular strategic deworming wi broad spectrum lung worm infection at was obtained by post mortem ant-helmentics. examination of infected lung was found to be almost 3 Animals should not be allowed to have access to times higher an at at of e prevalence of lung moist and swampy pastures. worm infection obtained by coprological examination. Prohibitions of sheep to graze early in e morning The higher prevalence in post mortem examination agrees and evening and in rainy weaer when e wi e finding of Teffera [4] around Dessie and intermediates host (snail and slug) are prominent. kombolcha, Frewengel [5] in and around Mekele and Isolation of most susceptible age groups (young) Eyobe [40] in Assela who reported higher prevalence in from adult in e first season of grazing. postmortem an coprological examination. Supplementation of additional feed to sheep s to But, e present finding disagrees wi e finding make well nourished and good body condition. of Sissay [6] in Bahir Dar, Paulos [39] in Arsi (chilallo) who reported higher prevalence in faecal an post ACKNOWLEDGEMENT mortem examination. This might be associated wi e difference in e meods followed in e detection of First of all I would like to ank GOD and Jimma lung worm larvae and e absence of larvae in e University for sponsoring is research esis. I would prepatent or post patent phases [16]. The oer reasons also like to ankamhara Regional State Laboratory could be due to ose larvae which reach e lungs of workers for eir willingness to help me in my research by sheep remain in e parenchyma and become encysted in giving e necessary laboratory materials and for fibrous nodules. Because such nodules may not be demonstrating e techniques of lung worm identification. deposited in air passages [11]. The last but not e least my heart feeling anks extends The result of is study revealed at M.capilaries is to all my family for eir uncountable support morally and e most prevalent of e total lungs examined and is financially in my educationand overall life. result agrees wi e reports of Muluken [14] and Sisay [13] at Bahir Dar. But is study disagrees wi reports of REFERENCES Nestanet [0] in Debrebirhan and Uqubazghi [30] in Hamasein.This could be associated wi differences in 1. FAO (Food and Agriculture Organization of e agro- ecology in Bahir Dar and e suitability of Lake United Nations), Eiopian Livestock sector Tana and River Abay for e survival of e intermediate development project. Preparation Report, FAO, host in case of M. capilaries. Rome, Italy, 1: 51.. Aklilu, Y., 00. An Audit of e Livestock Marketing CONCLUSION AND RECOMMENDATIONS Stages in Kenya, Eiopia and Sudan, Issue and Proposed Measure Community-based Animal Heal The study on lung worm infection of sheep using and participatory Epidemiology unit, Pan-African faecal and post mortem examination in and around Bahir Programme for e Control of Epizooties Organization Dar revealed prevalence of 0.% and 60.5% respectively. of African unity/ Inter African Bureau for Animal The respiratory nematodes were D. filaria, M. capillaries Resource, : 34. and P. rufescens. This high prevalence of Verminous 3. EPA (Eiopian Privatization Agency), 00. Eiopia pneumonia as e result of ese ree species is Animal Generic Resource Information, 5: considered as one of e important nematode infection for 4. CSA, (Central Statistics Auority), 004. The 001 sheep in e study area. It is found at young sheep were /00 Eiopian Agricultural Sample Summary most affected by D. filaria, while adult were, most Executive, Addis Ababa, Eiopia. 77

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