Nematode infection and its therapy in some zoo ruminants

Transcription

1 Parasit, hung., 25: 69-77,1992 Hungarian Society of Parasitologists Nematode infection and its therapy in some zoo ruminants Borisz EGRI and Gyöngyi KREPSZ* Department of Animal Physiology and Animal Health, Faculty of Agricultural Sciences, Pannon University for Agricultural Sciences, Mosonmagyaróvár, Vár 2, H-9201, Hungary (Received 26 July, 1992) Abstract: The gastrointestinal nematode fauna and the intensity of nematode infection were determined in some ruminant species in the zoo of Győr in 1990 by a faecal egg count technique. The ruminants included in the study were 4 North American and 2 European bison, 7 llamas and 3 Hungarian Grey cattle. After surveying their helminth fauna, the animals were treated with Vermitan paste (Sanofi-Chinoin) administered at a dose of 10 mg/kg body weight, hidden in delicacies (apple, carrot, bread) fed to the animals. The faecal samples collected after the treatments contained mainly eggs of the genera Trichostrongylus and Haemonchus. In faecal samples of bison, the eggs of Strongyloides papillosus, Toxocara vitulorum, Trichuris ovis and Nematodirus sp. were also demonstrated. Egg shedding stopped after the anthelmintic treatments. Key words: Bison, llama, Hungarian Grey cattle, helminthological investigation, Zoo of Győr (Hungary), Vermitan paste INTRODUCTION The assessment of predicted losses forms the basis of judging the economic efficiency of control (Kassai 1989). Helminth infections cause serious problems not only in farm animals but also in zoos. The helminthoses of zoo ruminants (e.g. llamas and bison) are problems common to every zoo. Consequently, the protection of these animal species against helminth parasites is by no means negligible. If nematode infections occur among zoo ruminants, the therapeutic interventions are aimed at minimizing the worm burden rather than at complete elimination of the helminth population, as the latter would be an almost illusory effort. * graduating student of agriculture

2 In harmony with the above facts, the objective of our study was to survey the prevalence of nematode infections in the given zoo population of bison, llama and Hungarian Grey cattle, and then to study the efficacy and mode of action of a nematocidal preparation successfully used in domestic ruminants. Review of common nematode species of bison and llamas According to data of the literature (Wade et al. 1979, Boever 1986, Tessaro 1989, Drozdz et al. 1989), members of the genera Trichostrongylus, Cooperia, Ostertagia and Haemonchus are the most prevalent in bison and llamas (see Table 1). Tessaro (1989) reviewed those infectious, parasitic and noninfectious diseases of North American bison populations which may occur in cattle and other ruminant species as well. He established that cross-infection between the bison and other artiodactylous mammals was possible, and indicated Babesia bigemina and Ostertagia ostertagi infection as the primary causes of deaths. He attributed poor growth and the different clinical signs observed to nematodes parasitizing the gastrointestinal tract. Table 1 Commonest nematodes parasitic in the gastrointestinal tract of artiodactylids (on the basis of data reported by W. J. Boever (1986) Parasite genus Location of adult worm Clinical signs produced Haemonchus abomasum oedema, haemorrhage, anaemia Ascarops stomach occasionally diarrhoea Physocephalus stomach occasionally diarrhoea Hyostrongylus stomach occasionally diarrhoea Ostertagia abomasum oedema, haemorrhage, anaemia Trichostrongylus abomasum oedema, haemorrhage, anaemia Cooperia small intestine diarrhoea, lack of appetite, emaciation Strongyloides small intestine diarrhoea, weakening Oesophagostomum small intestine, diarrhoea, weakening large intestine diarrhoea, weakening Researchers of the University of Colorado (Cheney and Allen 1989) studied helminth infections, more closely the prevalence of nematodes, in North American llamas. They developed several treatment methods against nematode species. By faecal examination, they demonstrated the following genera of Trichostrongylidae: Haemonchus, Cooperia, Bunostomum, Trichostrongylus, Ostertagia, Oesophagostomum. In faceal samples from South American llamas, Cheney and Allen (1989) detected the genera Spiculopteragia, Lamenema, Graphinema and Camelostrongylus. They established that the clinical signs produced by nematodes in llamas are similar to those reported for cattle and sheep. In addition to the common signs (diarrhoea, anaemia, exsiccation, emaciation), breaking of the staples and a reduction in their length and diameter were observed in the same way as in the case of sheep.

3 From New Zealand llamas, Arthur (1991) demonstrated the nematode genera Nematodirus, Ostertagia, Trichostrongylus and Cooperia. He established that the anthelmintics used in domestic ruminants can be successfully used also in llamas. Gevrey (1991) reported on an experiment conducted in Lyon, in which 6 ewes and 7 llamas were kept on the same pasture for 21 days (from 3 to 24 March). He found that parasitic infections were intertransmissible between the two species. By faecal examination, first Trichostrongylus and Trichuris spp. were demonstrated from both llamas and sheep. Later on, the lancet fluke (Dicrocoelium lanceolatum) was also found in both species. (Trichostrongylus colubriformis and Metastrongylus species were also observed at postmortem examination). The lambs that had been raised helminthfree were infected by larvae present in the llamas' faeces. Their abomasum was found to contain Trichostrongylus colubriformis while in their small intestine Metastrongylus spp. were present. Therapy and prevention of nematode infection Ruminants affected with nematode infections are often treated with benzimidazole derivatives. Several of the benzimidazole derivatives have the advantageous property of destroying both the eggs and the hypobiotic nematode larvae (Kassai 1989). Cheney and Allen (1989) tested the efficacy of preparations that had already been tried out in other ruminants, e.g. mebendazole, fenbendazole, thiabendazole, levamisole or ivermectin. They found that levamisole was slightly toxic when used simultaneously as a pour-on against ectoparasites. Of the preparations tested, ivermectin and fenbendazole were the most effective against the nematode parasites of llamas. Vermitan, a preparation containing albendazole as active ingredient, has been used successfully against the endoparasites of sheep and cattle. When administered at a dose of 7.5 mg/kg body weight, it had % efficacy against the adult stages of Haemonchus, Ostertagia, Cooperia, Trichostrongylus and Oesophagostomum. At a lower dose, it showed 95% efficacy against Bunostomum infection. Against Trichuris species, however, the efficacy of Vermitan administered at a dose of 10 mg/kg body weight was only 83%. Albendazole is effective against fasciolosis, too (Merényi 1990). The basic aim of anthelmintic treatment is to destroy the adult worms. The following two basic processes are essential for the survival of adult worms: - Availability of chemical energy for the different vital functions (energy-generating metabolic processes). - Possibility to feed within the host organism (neuromuscular coordination). Depending on their active ingredient, anthelmintics have different points of attack. Albendazole belongs to the benzimidazole compounds which exert their effect through the inhibition of energy-producing metabolic processes. They locally block the fumarate reductase enzyme system, thereby inhibiting mitochondrial function; as a result, energy release will be inhibited. Albendazole kills helminths through its metabolites (albendazole sulfoxide, albendazole sulfone) "detoxified" by the host organism. It is absorbed through the wall

4 of the rumen and gets into the liver, where it undergoes sulfonation or sulfoxigenation during the detoxification processes. The metabolites get into the plasma, from where they rediffuse into the gastrointestinal tract where they exert their effect (Takáts 1986). MATERIALS AND METHODS The studies were conducted in the "János Xantus" zoo of Győr. The data of animals included in the experiments are shown in Table 2. Table 2 Data of animals included in the study Species Age (years) Sex Number Lama glama 4-10 female 4 (2 pregnant) Lama glama 1/2-1 male 2 Lama glama 7-10 male 1 Bison bison 7 female 2(pregnant) Bison bison 7 male 1 Bison bison 4 male 1 Bison bonasus 7 female 1 Bison bonasus 7 male 1 Bos taurus primigenius hungaricus 7 female 1 (pregnant) Bos taurus primigenius hungaricus 1/2 male 1 Bos taurus primigenius hungaricus 7 male 1 Keeping of the animals The bisons were kept in pairs (one bull and one cow) in adjacent pens. (However, when cleaning the pens, the following routine was followed: the 4 American bison were driven into a run and the European bison were driven to their place; in this way, one run was always empty, and bedding, manure removal and feeding could be done easily). The pair of Hungarian Grey cattle was kept adjacent to the bison. The llamas were kept in a joint pen (however, they were often let out into a larger run, together with other herbivorous animals including deer, Cameroon dwarf goats, a Hungarian halfbred mare, and ponies). Nematode infection and its therapy Spontaneously excreted faecal samples were collected from the ground into plastics jars, in two series: the first series lasted from 4 May 1990 to 5 July 1990 and the second from 5 October 1990 to 11 December In order to determine the prevalence of nematode infection, the samples collected before medication (on day -7 and day 0) were examined by Fülleborn's method as follows.

5 The faeces to be examined was thoroughly crushed and mixed with an approximately tenfold volume of concentrated saline (specific gravity: about 1,200) in a thick-walled plastics jar, then was filtered through a metal filter into a porcelain cup having a beaker during constant mixing. The filtrate was poured into a centrifuge tube and spun for 3 min. During centrifugation and standing, the eggs rose to the surface from where they were picked with the help of a glass rod and transferred onto a slide previously smeared with a mixture of egg white and glycerol in a thin layer. The surface of the liquid column was touched three times; first the central part containing the largest number of eggs, then the surfaces nearer to the wall of the centrifuge tube. Three drops were placed on the slide and then examined under a microscope. Vermitan paste, a white, odourless preparation of Sanofi-Chinoin Pharmaceuticals Co. was used as anthelmintic at a dose of 10 mg/kg body weight on day 0. The paste was administered to the animals orally, kneaded in the soft part of bread or hidden in the inside of carrots or apples. The body weights (Lama glama 100, Lama pacos 70, Bison bonasus up to 1000 and Bison bison up to 1000 kg, respectively) were estimated according to Berthier (1986). Treatment was followed by the collection of faecal samples at specific intervals (day 1,7,30 and 60). The samples were analysed to determine the number of eggs per gram of faeces (EPG). Quantitative evaluation was performed with the help of a McMaster's chamber. Helminth eggs were identified with the help of the keys proposed by Thienpont et al. (1979) and Mehlhorn et al. (1986). RESULTS The results of the survey are shown in Tables 3-5 and in Figs 1-2. Table 3. Total egg counts of nematode species per gram of faeces Parasite eggs (EPG) L. glama B. bison B. bison B. taurus p. h. Trichostrongylus sp Haemonchus contortus Strongyloides papillosus Cooperia sp Trichuris ovis Toxocara vitulorum Nematodirus sp Ostertagia sp During the anthelmintic treatments, a phenomenon that could be a side effect was observed only in one case, on 12 October: after ingesting the preparation, the American bison bull showed intensive salivation and nasal discharge which lasted 3 minutes. No subsequent complications occurred in that case either.

6 Table 4 Prevalence of infection in the different groups of animals before the treatment Parasite eggs 1st period of experiment 2nd period of experiment (EPG) L.g. B.bi. B.bi. B. bo. L.g. B. bi. B. bi. B. bo. B. t. T.-strongylus sp. 4 a /3 b -/- -/1 2/1 27l d 1/2 1/5 -A -/- S.papillosus -/- 1/- 1/- -/- -/- -/- -A -/- -/- Tox. vitulorum -A 1/1 -A -/- -/- -A -A -A -/- Trichuris ovis -A -A -A -A -A -A -A -A -/- H. contortus -A -A -A -A -A -A -A -A 1/8 Nematodirus sp. -A -A -/- -A -A -A 7-1/- -/- a b 4 May (day -7) 11 May (day 0) c d 5 October (day -7) L. g. = Lama glama B. bo. = Bison bonasus 12 October (day 0) B. bi. = Bison bison B. t.. =Bos taurus p. h. Table 5 Rate of helminth egg shedding (EPG) by animals in the first period (from 11 May to 5 July) and in the second (from 16 October to 11 December) period of experiment Parasite eggs (EPG) Date L. glama B. bison B. bison B. bonasus B. taurus p. h. (a pair) (dam & her son) T-st. sp. H. com. T-st. sp. T.-st. sp. Coop. sp. T-st. sp. H. cont. 11 May May June July October October November December T-st. sp. = Trichostrongylus sp. H. con. = Haemonchus contortus Coop. sp. = Coopperia sp. DISCUSSION In contrast to the results reported by Wade et al. (1979), Boever (1986), Tessaro (1989), Drozdz et al. (1989), and Cheney and Allen (1989), in this study Trichostrongylus infection was found to be most prevalent in the llamas and in the American as well as European bison. The prevalence of other nematode species (e.g. Nematodirus, Haemonchus, Strongyloides, Cooperia, Trichuris, Toxocara) was relatively low. In contrast, in the Hungarian Grey cattle Haemonchus contortus infection was of decisive importance; apart from that, only Trichostrongylus and Ostertagia species were identified in them. The number of nematodes present gradually decreased after treatment of the animals with Vermitan paste (Sanofi-Chinoin) hidden in their favourite titbits. Infection recurred only if the preparation was not used with sufficient regularity.

7 Fig.l. Mean shedding of Trichostrongylus eggs by bison and llamas in the first period of experiment PPG O- ÂAÂ Lama glama Bison bison (dam and her son) Bison bison Bison bonasus Bos taurus p. h Oct. 25 Oct. 1 8 Nov. 11 Dec. Fig.2. Shedding of Trichostrongylus eggs by bison and llamas and shedding ofh. contortus eggs by Hungarian Grey cattle in the second period of experiment

8 The causes of reinfection may have included the cleaning method used for the pens of bison and the fact that the llamas were occasionally let out into a run they shared with other herbivorous animals. Bulk feeds derived from different sources may also have acted as potential transmitters of infection. It can be established that Vermitan paste possessed no toxic or fetopathic effects in the species tested, as two healthy llama calves and a Hungarian Grey calf were born during the period of experiment. In view of the above facts, we propose to use the preparation regularly, at half-year intervals, in order to maintain a satisfactory level of hygiene in zoo ruminant populations. Egri B. és Krepsz Gy.: Egyes állatkerti kérődzőfajok fonalférgessége és annak terápiája A szerzők 1990-ben a magyarországi győri állatkertben bélsármintákból meghatározták néhány kérődzőfaj fonalféreg-fertőzöttségének mértékét. A kísérleti állományt 4 amerikai és 2 európai bölény, 7 láma és 3 magyar szürke marha alkotta, amelyeket a felmérő helmintológiai vizsgálatok elvégzése után Vermitan paszta (Sanofi-Chinoin) 10 mg/ttkg dózisával kezeltek. A paszta adagolása az állatok csemegéibe (alma, sárgarépa, kenyér) rejtve történt. A kezeléseket követően gyűjtött bélsármintákban döntően a Trichostrongylus és Haemonchus nemek petéit találták. Bölényeknél az említetteken kívül Strongyloidespapillosus, Toxocara vitulorum, Trichuris ovis és Nematodirus sp. petéit határozták meg. Az anthelmintikus kezeléseket követő 2-4 hét után a peteürítések megszűntek. REFERENCES Arthur, D. G. (1991): Diseases of llamas and alpacas. - Surveillance Zealand), 18 (2): 21. (MAF, New Berthier, J. L. (1986): Quelques aspects de la medicine des ruminants sauvages en captivité. - Ree. Méd. Vet., 123 (3): Boever, W. J. (1986): Artiodactylids. In: Parasitic Diseases. - Saunders Co., Philadelphia, (cit in: CAB International CD-ROM database). Cheney, J. M. and Allen, G. T. (1989): Parasitism in llamas. - Veterinary Clinics of North America: Food Animal Practice, 5 (1): Drozdz, J., Demiaszkiewicz, A. W. and Lachowicz, J. (1989): The helminth fauna of free-ranging European bison (Bison bonasus). - Acta Parasit. Polon. 32 (2): , (cit in: CAB International CD-ROM database). Gevrey, J. (1989): Lamas et moutons: Observations d'intertransmissibilite helminthique. - Bull. Soc. Franc. Parasit. 7 (2): Kassai, T. (1989): Anthelmintikumok használata a korszerű állattenyésztésben, különös tekintettel a kérődzők legelői helmintózisaira (Use of anthelmintics in modern livestock farming with special reference to the pasture helminthoses of ruminants. Review article). - Magy. Állatorv. Lapja 44 (9):

9 Kotlán, S. and Kobulej, T. (1972): Parazitológia (Parasitology). - Mezőgazdasági Kiadó, Budapest, 503 pp. Mehlhorn, H., Düwel, D. and Raether, W. (1986): Diagnose und Therapie der Parasiten von Haus-, Nutz- und Heimtieren. - G. Fischer Verlag, Stuttgart, New York, pp , Merényi, L. (1990): Albendazol-készítmények hatékonyságának vizsgálata szarvasmarhák és juhok belső élősködői ellen (Study on the efficacy of albendazole preparations against internal parasites of cattle and sheep). - Magy. Állatorv. Lapja 45 (5): Nemeséri, L. and Holló, F. (1961): Állatorvosi Parazitológiai Diagnosztika (Veterinary Parasitologic Diagnosis). - Mezőgazdasági Kiadó, Budapest, pp , Takáts, Cs. (1986): Az anthelmintikumok hatásmechanizmusa (Mechanism of action of anthelmintics. Review article). - Magy. Állatorv. Lapja 41 (1): Tessaro, S. V (1989): Review of the diseases, parasites and miscellaneous pathological conditions of North American bison. - Can. Vet. J. 30: , (cit in: CAB International CD-ROM database). Thienpont, D., Rochette, F. and Vanparijs, D. F. J. (1979): Diagnose von Helminthosen durch koproskopische Untersuchung. - Janssen Research Foundation, Beerse, Belgium, pp Wade, S. E., Haschek, W. M. and Georgi, J. R. (1975): Ostertagiosis in captive bison in New York State: Report on nine cases. - Cornell Vet. 69: , (cit in: CAB International CD-ROM database).