A Review on Lungworm Infection in Small Ruminants

American-Eurasian Journal of Scientific Research 10 (6): 375-380, 2015 ISSN 1818-6785 IDOSI Publications, 2015 DOI: 10.5829/idosi.aejsr.2015.10.6.101124 A Review on Lungworm Infection in Small Ruminants Tewodros Alemneh Engdaw Woreta City Office of Agriculture and Environmental Protection, Eiopia Faculty of Veterinary Medicine, University of Gondar, P.O. Box: 196, Gondar, Eiopia Abstract: Lungworms are parasitic nematode round worms of e order Strongylida at infest e lungs of vertebrates.the most common lungworms belong to one of e two superfamilies, Trichostrongyloidea or Metastrongyloidea. Of which, Dictyocaulus and Protostrongylus are causes of lungworm infection in ruminants. The common causes of verminous pneumonia in sheep and goats are Dictyocaulus filaria (D. filaria), Protostrongylus rufescens (P. rufescens) and Muellerius capillaris (M. capillaris). D. filaria belongs to e super family Trichostrongyloidea while e latter two belong to Metastrongyloidea, which have direct and indirect life cycles, respectively. Of e two species, goats are more susceptible to lungworm infection. Depending on e severity of infection, age and immunological status of e animal, e clinical sign ranges from moderate coughing wi slightly increased respiratory rates to sever persistent coughing, persistent respiratory distress and failure. Diagnosis of e disease is by examination of e faeces wi Baermanization to detect e L 1 larvae in e laboratory and postmortem examination of e lungs of infected animals for adult worms isolation. Treatment of lungworm necessitates e use of appropriate Anelmentics which are effective against lugworm infections. The effective Anelmentics including Benzimidazoles, Levamisols and Ivermectin should be used in e treatment of e disease.the prevention and control of lung worm infection can be achieved most effectively by integration of ree interrelated approaches: administration of effective Anelmentic drugs, immunization and improved management practices. Key words: Dictyocaulus Protostrongylus Lungworm Infections Small Ruminants INTRODUCTION practiced, small ruminants account for 40% of cash income and 19% of e house hold meat consumption [7]. Livestock production in Eiopia contributes about Yet ese species have received much less attention 30-33% of agricultural gross domestic product (GDP) and from research and development agencies [8]. more an 85% of e farm cash income mainly rough And e economic benefits to e farmers remain marginal meat, milk, eggs, wool, hides and skins [1, 2]. Sheep and due to prevailing disease, poor nutrition, poor animal goats are e most numerous of man s domestic livestock. production systems and general lack of veterinary care Of e world 1.614 million sheep and 475 million goats, [9]. 65% and 95% respectively; are located in developing Helmines parasites of ruminants are ubiquitous and countries [3, 4]. As reported by International Livestock prevalent wi many tropical and sub-tropical Research Institute [5], Eiopia contributes 17 million environments of e world providing nearly perfect small ruminants. conditions for eir survival and development. However, Small ruminants are especially important in e more e clinical signs ey cause in infected animals can be extreme climates of e world. In Africa, ey are noted for less obvious an signs of oer livestock diseases. Partly eir ability to convent low opportunity cost feed in to for is reason, infections wi gastro-intestinal and oer high value products including meat, milk, fiber, manure helmines parasites are among e most neglected areas and hides [3, 4]. of veterinary care in much of e developing world. It has Small ruminants provide 33% of meat and 14% of milk however been established at high prevalence rates of consumption in Eiopia [6]. In e central high lands e infection wi less obvious sign associate wi poor where mixed crop-livestock production system is production and unriftness [10]. Corresponding Auor: Tewodros Alemneh Engdaw, Faculty of Veterinary Medicine, University of Gondar, P.O. Box: 196, Gondar, Eiopia. Tel: +251 9 20 49 98 20, E-mail: tedyshow@gmail.com, joteddy85@yahoo.com. 375

Up to half of all sheep deas and morbidity on farms environment is stabilized by e presence of long herbage in Eiopian highlands are caused by pneumonia and of free water. Under optimum conditions e larvae can endo-parasites [8]. Endo-parasites, including D. filaria, persist for over one year [19]. are major causes of dea and morbidity [8]. Prevention Lungworm parasites are host specific and common in and control of ese parasites is, erefore, critical to areas of mild high rain fall and abundant grass [14, 20]. enhance e economic benefit from ese species of The prevalence of infection is low in spring and summer livestock. However, e incidence of parasitic diseases and rises rapidly in e autumn and winter. When most including respiratory helminosis varies greatly from clinical cases are seen, wet summers give rise to heavier place to place depending on e relative importance of e burden in e following autumn and winter [20]. Over factors [11]. Very few and limited studies were done so far stocking, deficient feeding, previous or concurrent pertaining to respiratory helmines of small ruminants. infections predispose to infection [18]. Therefore, e objectives of is paper include e Sheep of all age are susceptible, but lambs of 4-6 following: to review and compile available literature mons of age are severely affected wi lungworms [21]. information on e characteristics of e parasite, about its Generally, only young ruminants in eir first grazing occurrence in animals, its meod of transmission, season are clinically affected, since on farms where e diagnosis and control of e disease, which will increase disease is endemic older animals have a strong acquired our understanding about e disease. immunity. Goats appear to be more susceptible to helmines an sheep as ey appear to develop less Literatures Review immunity. Sheep predominantly graze; pick up more Lungworm Infection of Small Ruminants parasites so have higher acquired resistance an goats (Verminous Bronchitis, Verminous Pneumonia): which mostly consume browse. Goats wi eir browsing Verminous pneumonia is a chronic and prolonged infection of sheep and goats caused by any of several parasitic nematodes, characterized clinically by respiratory behavior consume uncontaminated matter wi parasite larvae, so being less exposed to infective larvae and may erefore have lower acquired resistance an sheep [4]. distress and paologically by bronchitis and bronchopneumonia [12, 13]. It is infection of e lower respiratory tract, resulting in bronchitis or pneumonia, or bo [14]. Life Cycle: Lungworms of domestic ruminants have two forms of life cycle. One form is direct life cycle (Dictyocaulidae) in which e free living larvae undergo two moults after hatching and infection are by ingestion Etiology: Lungworms of domestic ruminants are nematodes at belongs to e phylum Nemaelmenes commonly named as round worms; classified under e super family Trichostrongyloidea and Metastrongyloidea [15]. Of which, Dictyocaulus and Protostrongylus are causes of lungworm infection in ruminants [16]. The common causes of verminous pneumonia in sheep and goats are D. filaria, P. rufescens and M. capillaris. D. filaria belongs to e super family Trichostrongyloidea while e latter two belong to Metastrongyloidea, which have direct and indirect life cycles respectively [13, 17]. Alough mixed infection may occur, D. filaria predominates in most outbreaks [12]. Epidemiology: Epidemiology depends more on pasture contamination by carrier animals. Pasture infectivity is related to rainfall which stimulates e activity of bo e larvae and e mollusk [18]. Moisture is essential for e survival and development of e larvae. The larvae is active at moderate temperature of 10-21 C. Larvae survive best in cool, damp surroundings especially when e of e free L. The oer form is indirect life cycle 3 (Protostronglidae) whereby e first two moults usually take place in an intermediate host (Snails or slugs) and infection of e final host is by ingestion of intermediate host [15]. Paogenesis: The paogenic effect of lugworms depend on eir location wiin e respiratory tract, e number of infective larvae ingested, e animal immune state and on e nutritional status and age of e host [13, 22]. The relative paogenicity of each lungworm depends on its predilection site. D. filaria lives in e trachea and bronchi so aspirated eggs, larvae and debris affect a large volume of lung tissue. It is erefore e most paogenic species. Adult P. rufescens are found in smaller bronchioles, so associated lesions are much smaller. M. capillaris is found in e lung parenchyma where it becomes encysted in fibrous nodules; lesions are erefore confined to its immediate surroundings. Consequently, is worm is generally considered as involves heavy mixed protostrongyloid infection and 376

Fig. 1: Lodged lungworms in e lung tissues of sheep and goats and eir effects impair pulmonary gaseous exchange [21]. It is suggested Dictyocaulus species of lungworms of cattle and at when e larval stages of M. capillarismigrated sheep are usually seen in e sputum as egg containing rough e walls of small intestine, e resulting damage larvae raer an larvae in e faeces[24]. In M. may predispose to enterotoxaemia [10]. Infection wi scapillaris, ose larvae which reach e lungs of sheep more an one species is common and course of infection remain in e parenchyma and become encysted in fibrous is usually chronic [18]. nodules and because such nodules may not contain adults of bo sexes, fertile eggs may not be deposited in Clinical Finding: The clinical course of lungworm e air passages. For is reason, e number of larvae in infection depends on severity of infection, age and e faeces is often no indication of e degree of immunological status of e animal [18]. Signs range from infestation [21]. moderate coughing wi slightly increased respiratory During identification of e larvae, e presence of D. rates to sever persistent coughing, persistent respiratory filaria was confirmed by e finding of e first stage distress and failure [13]. The most common signs of D. larvae wi an anterior protoplasmic knob and black filaria are coughing and unriftness which in endemic granular intestinal inclusions in e faeces[25]. The larvae areas is usually confined to younganimals. In more severe of P. rufescensand M. capillarisare differentiated by eir cases, dyspnea and tenacious nasal discharges are also characteristic feature at e tip of eir tail. P. rufescens present. The signs may be accompanied by diarrhea and has a wavy outline at e tip of its tail, but devoid of anemia due to concurrent gastrointestinal dorsal spine. On e oer hand, M. capillaris has an Trichostrongylosis of fasciolosis [15]. In M. capillaris undulating tip and a dorsal spine [26]. and P. rufescens infection, pneumonic signs have rarely been observed and infections are almost always Postmortem Examination: Lungs from selected animals unapparent being identified only at necropsy [15]. were palpated for e presence of Protostrongylidea nodule. If e nodule present ey were trimmed off and Diagnosis: The factors at suggest lungworm infection worms extracted from e tissue by gentile comprising a are a history of exposure to previously grazed pasture by small non-calcified nodule or part of large nodule between animals of e same species, e presence of e disease two glass slides and en carefully testing e worm away in e area and failure to respond to standard treatments from e tissue. Air passages were opened starting from to bacterial or viral pneumonia [14, 20]. e trachea to e small bronchi wi fine blunt pointed scissors to detect e presence of adult Laboratory Diagnosis: In laboratory, 25 gram of fresh Dictyocaulidae[16, 18]. faeces will be weighed from each sample for e extraction At necropsy, most lesions are found in e of L 1 larvae using modified Baermann technique. The respiratory system. Wi infection by D. filaria, e paste enclosed in gauze fixed on string rod and bronchi, especially ose of e diaphragmatic lobes, submerged in clean glass tube filled wi fresh water. The contain tangled masses of worms mixed wi froy whole apparatus will be left for 24 hours. The larvae leave exudates. Atelectatic and infected lobules often surround e faeces and migrate rough e gauzes and settle at or extend ventrally from infected bronchi. Bronchioles e bottom of e glass. After siphoning of e infected wi P. rufescens often are closed wi worms supernatant, e sediment is examined under e lower and exudates; consequently, affected lobules may be power of e microscope [13, 23]. atelectatic and infected. Lungs infected wi M. capillaris 377

Dictyocaulus fillaria lung worm of sheep and goats Muellerius capillaries lung worm of sheep and goats Fig. 2: Species of Lungworms in Small ruminants Treatment: Strong acquired resistance against dictyocauliasis of bovine and ovine species by natural infection is well documented fact. However, owing to e undetermined number of infective larvae at could be ingested in e field and e accompanying disease process makes it unreliable [28]. Treatment of lungworm necessitates e use of appropriate Anelmentics which are effective against lugworm infection [29]. The effective Anelmentics including Benzimidazoles, Levamisols or Ivermectin Fig. 3: Adult Lungworms isolated from e respiratory should be used in e treatment of edisease since tract of small ruminants by postmortem clinical signs associated wi pulmonary paology are examination not rapidly resolved by mere removal of adult lungworms [15, 22, 29]. contain red, grey or green lobules 1 to 2 mm in diameter. These lesions, located in e sub-pleura of Control and Preventions: The objective of prevention and e diaphragmatic lobes, vary in consistency, control can be achieved most effectively by integration of numberand shape [12]. Lung nodules as a result of ree interrelated approaches of anelmentic drugs, M. capillaris infection have e feeling of lead shot immunization and improved management practice [17]. [25]. Management practice such as provision of ample Infestation of goats by M. capillaris leads to a nutrition increases e resistance of e host and diffuse infection quite different to e nodular reaction in erefore it is important for e control of Dictyocaulosis. sheep and to e production of an interstitial pneumonia Larvae of Dictyocaulus may persist and develop in [22, 27]. swampy pastures and may serve as a source of infection; 378

erefore, ose susceptible animals should not be and controlled by integration of effective Anelmintic allowed to have access to such areas because young drug administration, vaccination and improvement of e hosts of all kids are more susceptible to Dictyocaulus management and husbandry system. an adults. Animals must be placed on dry pasture and supplied wi clean drinking water; moist pasture must be ACKNOWLEDGEMENTS avoided while dry pasture is fairly safe, because e infective larvae are not very resistance to dryness. Young The Auor s gratitude goes to all his friends and stock should be separated from oer stock [15]. University of Gondar, Faculty of Veterinary Medicine Extinction of e snail intermediate host is an staffs for material and logistic supports and eir additional measure important for e control of cooperation to bring is paper to completion. Metastrongyloidea. This technique enables to control e nude slugs and shelled snails more easilyand spreading of lime has been recommended for is purpose. The REFERENCES snails creep up plants in e early morning and evening and rainy weaer, e animals should, erefore, not be 1. Befekadu and N. Berhanu, 2000. Annual Report of allowed to graze at such times, particularly in e autumn e Eiopian Economy.1999-2000 Addis Ababa, when e infection most frequently occur [30]. Eiopia Economic Association, pp: 1199. Control of lungworm infection in first year grazing 2. ESPA, 2003. Proceeding of e 10 annual conference sheep and goats has been achieved by e use of of e Eiopian society of animal production prophylactic anelmintic regimens eier by strategic (ESAP). Addis Ababa, Eiopia. early season treatment or by administration of rumen 3. FAO, 1986. Small ruminant production in e bolus [15]. developing countries, in proceedings of an expert The best meod of preventing verminous consultation held in Sofia, Bulgaria, 8-12 July 1985, pneumonia is to immunize all young sheep and goats wi vol, 58, 4. No.1. lungworm vaccine [15]. Vaccine is available for D. filaria 4. Wilsmore, T., 2006. Diseases of small ruminants in where is worm is a particular problem [21]. This live Eiopia, e veterinary epidemiology and economics vaccine, consisting of larvae attenuated by irradiation, is research unit school of agriculture s policy and given orally to young's aged 8 weeks or more. Two doses development e university of read, UK., pp: 67-72. should be administered in order to allow a high level of 5. ILRI, 2000. Handbook of livestock statistical immunity and to develop resistance. Vaccinated animals for developing countries socio-economic and should be protected from challenge until two weeks after policy research working paper 26. ILRI eir second dose [15]. (International livestock research institute), Nairobi, Kenya, pp: 299. CONCLUSION 6. Asfaw, W., 1977. Country report, Eiopia in proceeding of a seminar on livestock development Lungworms of domestic ruminants are nematodes st policies in Eastern and Souern Africa, 28 July - 1 at belongs to e phylum Nemaelmenes commonly August, 1997.Mbabane organized by CTA, named as round worms; classified under e super family OAU/IBAR e ministry of Agriculture cooperative, Trichostrongyloidea and Metastrongyloidea. Among Swaziland. ese, Dictyocaulus and Protostrongylus are causes of 7. Fletcher, I. and A. Zelalem, 1993. lungworm infection in ruminants. Of e two species, Ruminant productivity in Eiopia mixed faming goats are more susceptible to lungworm infection. Female system. In: proceeding of e 4 national livestock animals, young animals of less an one year of age, improvement conference, 13-15 November, IAR, poorly conditioned animals and ose managed under Addis Ababa, Eiopia. extensive system of production are more prone to 8. ILCA, 1990. Annual report, 1989 ILCA lungworm infection. The respiratory nematodes, D. (international livestock center for Africa), Addis filaria,m.capillaris and P.rufescens, are e species of Ababa, Eiopia, pp: 37. lungworms most commonly affecting small ruminants. 9. Sissay, M.M., A. Uggia and P.J. Waller, 2006. The clinical picture of e disease ranges from moderate Epidemiology and seasonal dynamics of coughing and sneezing to sever respiratory distress and gastrointestinal nematode infection of sheep in a failure. Lungworm infection in ruminants can be prevented semi-arid region of eastern Eiopia. 379

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