EPIDEMIOLOGICAL STUDY ON THE PREVALENCE OF ENDOPARASITES OF EQUINES IN ALBANIA EPIDEMIOLOŠKI STUDIJ PREVALENCIJE ENDOPARAZITA KOPITARA U ALBANIJI Postoli R., Robaj A., Ceroni V., Zalla P., Andoni E., Çaushi A 5 Abstract - The objective of the study was to investigate the prevalence of parasites in equines in Albania, where there is still a considerable number of working equines, particularly the donkeys. A total of 336 (68 horses, 190 donkeys and 78 mules) faecal samples were tested using standard coprological methods. The results showed that an average of about 47.8% of animals used to obtain faecal samples, were infected with one or more parasitic elements. In particular, amongst the examined equines, 60.3% of the horses, 44.2% of the donkeys and 46.2% of the mules were infected. Strongylus spp. was found in 47.3%, Anoplocephala spp. in 3.8%, Dictyocaulus arnfieldi in 7.6% and Parascaris equorum in 1.9% of the animals. Strongyles were significantly more prevalent between October and December compared to the rest of the year. Examination of larval cultures according to geographical distribution, showed that 41%, 43% and 44% of individuals were found positive for small strongyles. A total of 11 (8.9), 15 (16.9) and 19 (15.3) individuals according to above geographical distribution were found infected with Strongylus vulgaris. Key words: equine, epidemiology, strongyles, blood parasites, serology Kratak sadrţaj- Cilj studije je istraţivanje prevalencije parazita u kopitara u Albaniji, gdje još ima znatan broj radnih konja i posebno magaraca. Ukupno je testirano 336 (68 konja, 190 magaraca i 78 mula) uzoraka fecesa koristeći standardne koprološke metode. Rezultati su pokazali da je 47,8% testiranih ţivotinja zaraţeno sa jednim ili više 5 Postoli Rezart, DVM, PhD, Department of Clinical Subjects, Faculty of Veterinary Medicine, Agricultural University of Tirana, Kodër Kamëz, mob: +355684077442, fax: +35542257411, Albania, e-mail: rpostoli@yahoo.com; Robaj Avni, DVM, PhD, Department of Veterinary, Faculty of Agricultural and Veterinary, University of Prishtina, Kosovo; Ceroni Vangjel, Associated Professor, Department of Clinical Subjects, Faculty of Veterinary Medicine, Agricultural University of Tirana, Albania; Zalla Pëllumb, DVM, PhD, Department of Morph- Functionally Subjects, Faculty of Veterinary Medicine, Agricultural University of Tirana, Albania; Andoni Egon, DVM, MSc, Department of Morph-Functionally Subjects, Faculty of Veterinary Medicine, Agricultural University of Tirana, Albania; Çaushi Alfred, DVM, MSc, Department of Morph-Functionally Subjects, Faculty of Veterinary Medicine, Agricultural University of Tirana, Albania. Veterinaria 59 (1-4), 37-45, Sarajevo 2010. 37
parazitnih elemenata. Od ispitivanih kopitara: 60,3% konja, 44,2% magaraca i 46,2% mula bilo je zaraţeno. Strongylus spp. je pronaċena u 47,3%, Anoplocephala spp. u 3,8%, Dictyocaulus arnfieldi u 7,6% i Parascaris equorum u 1,9% ţivotinja. Strongilide su bile znatno prevalentne u periodu oktobar - decembar usporeċujući sa ostatkom godine. Ispitivanje larvalnih kultura u skladu sa geografskom distribucijom pokazalo je da je 41%, 43% i 44% ţivotinja bilo pozitivno na male strongilide. Ukupno 11 (8,9%), 15 (16,9%) i 19 (15,%3) ţivotinja u skladu sa gore navedenom geografskom distribucijom su zaraţene sa Strongylus vulgaris. Kljuĉne rijeĉi: kopitari, epidemiologija, strongilidi, paraziti krvi, serologija Introduction The equines have a number of different parasites, which have evolved to live in their intestine and blood. Internal parasites continue to be a significant threat to the health of equines. Even under proper management equines will become infested with internal parasites. Internal parasites of equines are of veterinary importance in many countries, where current methods of control rely almost entirely on the use of anthelmintics. Strongyle nematodes are the most important internal parasites of equines. Infection of equines with strongyles (nematodes of the superfamily Strongyloidea) is a widespread and serious cause of poor health throughout the world. Accordingly, considerable resources are directed towards their control. Patterns of transmission vary greatly with climate and management, therefore no worming program is universally applied. Since the mid-eighties, a widespread and frequent use of effective anthelmintics has resulted in the decreased occurrence of Strongylus vulgaris both in Europe and the USA (10, 14). Unlike the situation with Strongylus vulgaris, anthelmintic exposure has not had a similar impact on the small strongyles (subfamily Cyathostominae). This is partly attributed to benzimidazole resistance, which is a widespread problem in cyathostome populations (8, 9). The number of equines in Albania has declined gradually from 1990 until now, due to the changes in agriculture, transportation and communication. Recent years have seen the expansion of interests in the equine field to include participation in national events, and particularly more in using horses for pleasure. So, it has become important from the standpoint of the successful horse management to know more about parasitic infestation. Unfortunately, very little research on equine parasites has been done in Albanian regions. Work reported here represents the first attempt to provide comprehensive information on the prevalence of equine parasites occurring in Albania. The emphasis in the survey was on Strongylus species frequently associated with clinical problems in equines. However, the data were also collected on the prevalence of Parascaris, Anoplocephala and other species of parasites of secondary importance, which are nevertheless considered in the parasite control plan. 38
The aim of the present study was to investigate the prevalence of internal parasites in equines under conditions varying from limited antiparasitic treatment to intensive treatment in southeastern and northern territory of Albania. Additionally, the research was undertaken to obtain data on transmission of internal parasites in equine relative to season and geographic location. Comparison of these data with previous surveys of internal parasites of equine in Albania and Greece was also a goal. Materials and Methods Animals selected for survey A total of 336 (68 horses, 190 donkeys and 78 mules) faecal samples were tested using standard coprological methods. Samples came out from animals, which for reasons not overtly associated with clinical parasitism were made available for this survey by local veterinary practitioners and owners. 68 faecal samples were collected from horses, 190 faecal samples from donkeys and 78 faecal samples from mules. The study area consisted of 26 different regions in south-eastern and northern areas of Albania. 114 animals in southern, 118 in central and 104 in northern Albania were included, and a total of 81, 76, 87 and 92 individuals, respectively, were sampled each season in these regions. Background information regarding age, sex, breed, use, type of management, history of anthelmintic treatment, and environment was sought and recorded where possible. Animal faecal samples from the planes (approximately 0-200 m above the sea level), hills (> 200-700 m altitude) and mountains (> 700 m altitude) were obtained in this study. Parasitological procedures Faecal samples were taken directly from the rectum of each animal, mostly in the morning. All samples were transferred to the laboratory as soon as possible. The samples were refrigerated until examination, within 3 days for faeces. For better accuracy, each faecal sample was examined according to both the Teleman and Faust techniques knowing that Eimeria leukardi oocysts could only be detected by the Teleman s method. Faecal larval cultures were made to identify equines infected with Strongylus species (22). Pooled samples from each region were incubated at 24 C for at least 10 days. Third stage larvae were collected by Baermann procedure, and preserved in Lugol s solution. Parasitic elements were identified by microscopy with 40x magnification, according to the keys provided by Soulsby (19), Euzeby (7) and Thienpont et al. Statistical tests employed were the Chi-square test for prevalence. Veterinaria 59 (1-4), 37-45, Sarajevo 2010. 39
Results Prevalence of infection The prevalence of infection in each species and the percentage of every parasite involved are presented in Table 1. As a rule, all animals, especially mules, harbored more than one parasitic species. Excluding strongyles, which also were found in single infections, parasites were generally found in mixed infections mainly with strongyles. Six species of gastrointestinal parasites were found in this study. The results showed an average of about 47.8% of equines used to obtain faecal samples, were infected with one or more parasitic elements. The prevalence of infection was 60.3% for horses, 46.2% for mules and 44.2% for donkeys. Small strongyles (Cyathostominae) had the highest prevalence of infection. Large strongyles (Strongylinae) were detected in 13% of equines (Table 1.) Strongylus vulgaris was the only prevalent parasite with the corresponding prevalence of 11.8% for horses, 6.4% for mules, and 16.8% for donkeys. Strongylus westeri was detected in 5% of equines with the highest prevalence in mules. Five species of non-strongyloid parasites were detected (Table 1) with the prevalence ranging from 1.8-7.6%. Strongyles were detected in 47.3%, Anoplocephala spp. in 3.8%, Dictyocaulus arnfieldi in 7.6%, Oxyuris equi in 3.8%, Parascaris equorum in 1.8%, and Eimeria leukardi in 3.8% of the animals. Table 1 Prevalence of parasite species found in horses, donkeys and mules Tabela 1. Prevalenca parazitskih vrsta u konja, magaraca i mula Species Donkeys Mules Horses Total Examined Nr (%) 190 (100) 78 (100) 68 (100) 336 (100) Infected Nr (%) 84 (44.2) 36 (46.2) 41 (60.3) 161 (47.8) Strongylus spp 84 (44.2) 36 (46.2) 39 (57.4) 159 (47.3) Strongylinae 32 (16.8) 5 (6.4) 8 (11.8) 45 (13.4) Strongylus vulgaris 32 (16.8) 5 (6.4) 8 (11.8) 45 (13.4) Strongylus edentatus - - - - Strongylus equinus - - - - Cyathostominae 67 (35.2) 36 (46.2) 39 (57.4) 142 (42.3) Eimeria leuckarti 11 (5.7) - 2 (2.9) 13 (3.8) Anoplocephala 4 (2.1) 3 (3.9) 6 (8.8) 13 (3.8) perfoliata Parascaris equorum 3 (1.6) - 3 (4.4) 6 (1.8) Oxyuris equi 4 (2.1) 6 (7.7) 3 (4.4) 13 (3.8) S. westeri 7 (3.7) 8 (10.3) 2 (2.9) 17 (5.0) Dictyocaulus arnfieldi 11 (5.8) 8 (10.3) 7 (10.3) 26 (7.6) Effects of season on prevalence of strongyles infection Season had a significant effect on the prevalence of strongyles parasite (Chisquare test). A member of the Strongylinae (Strongylus vulgaris) was the most prevalent in summer 23%, followed by spring 17%, and autumn 7%. No difference was noted in 40
the prevalences of Strongylus vulgaris between the spring and summer season. Significant differences (P<0.05), however, were noted in the prevalences of Strongylus vulgaris in the spring and summer season in comparison with the autumn season. Small strongyles showed higher prevalence in autumn 62% than either in summer 42% or spring 35%, and were less prevalent (30%) during the winter (Table 2). Significant differences (P<0.05) were noted in the prevalences of small strongyles between autumn and other seasons. Table 2. Significant effects of season on the prevalence of strongyles infection in south-eastern and northern areas of Albania Tabela 2. Utjecaj godišnjih doba na prevalencu infekcija strongilidima u jugoistocnim i sjevernim regijama Albanije Season Autumn Winter Spring Summer Equines Nr (%) Examined 81 (100) 76 (100) 87 (100) 92 (100) Infected 52 (64.2) 23 (30.3) 38 (43.7) 48 (52.2) Strongylinae 6 (7.4) 3 (4.0) 15 (17.2) 21 (22.8) Strongylus vulgaris 6 (7.4) * 3 (4.0) * 15 (17.2) 21 (22.8) Strongylus edentatus - - - - Strongylus equinus - - - - Cyathostominae 50 (61.7) 23 (30.3) * 30 (34.5) * 39 (42.4) Out of the total number of equines examined, 51 equines (41.6%) from the planes, 63 (50.8%) from the hills and 45 (50.6%) from the mountains were infected with Strongylus species (Table 3). Strongylus species showed higher prevalences in the mountainous and hilly geographical areas with the lowest prevalence occurring in the planes, but these results were not statistically significant. Table 3. Numbers and prevalence of strongyles infection found in 3 geographical regions Tabela 3. Brojevi prevalence infekcije Strongilidima u 3 geografske regije Geographical region Planes Mountains Hills Total Examined 123 (100) 89 (100) 124 (100) 336 (100) Infected 52 (42.3) 45 (50.6) 64 (51.6) 161 (47.8) Strongylus spp 51 (41.6) 45 (50.6) 63 (50.8) 159 (47.3) Strongylus vulgaris 11 (8.9) 15 (16.9) 19 (15.3) 45 (13.4) Strongylus edentatus - - - - Strongylus equinus - - - - Cyathostominae 50 (40.7) 38 (42.6) 54 (43.6) 142 (42.3) Examination of larval cultures according to geographical distribution showed that 41%, 43% and 44% of equines were found positive for small strongyles. A total of 11 (8.9), 15 (16.9) and 19 (15.3) individuals according to the above geographical distribution, were found infected with Strongylus vulgaris. No difference was noted in the prevalence of strongyles among different geographical areas. Veterinaria 59 (1-4), 37-45, Sarajevo 2010. 41
Discussion This nationwide survey on the prevalence of parasitic infection in equines in Albania was carried out from September 2008 till October 2009, and involved 336 animals. In a recent survey carried out in Tirana regions (16), 80% of equines were found positive for strongyle egg counts in the faeces. In the present survey only 50% of individuals were infected. The present results (13% and 42% for large and small strongyles, respectively) indicate a significant decrease in infection rate as compared with previous surveys in Albania (16) and Greece (11, 12, 13), when the infection rate was approximately 100%. These findings are in accordance with those of Sotiraki et al. (18), who reported a reduction of strongyle infection among equines in Greece. One obvious explanation is the recent widespread use of palatable and highly efficient anthelmintic paste for equines available since 1975, which has reduced the population of adult worms. What is worth noting is that the prevalence of small strongyles in both studies (Albania and Greece) appears to be more stable. After 1980, the occurrence of large strongyles began to decline while the prevalence of small strongyles increased (10). It should be noted that anthelmintics are less effective against small strongyles than large strongyles, mainly for the following two reasons: a) normal doses of modern anthelmintics often fail to eradicate encysted third- and fourth-stage larvae of small strongyles (7, 21) and b) at least 10 species of small strongyles have developed resistance to benzimidazoles (17). Repeated surveys would provide data to confirm or refute this hypothesis. The rate of parasitic infection in horses was higher than in donkeys and mules. In our view, this could be caused by very irregular, if any, antihelminitic treatment received by the equines, according to the questionnaires filled out by the owners. On the other hand, some charity organizations operate in the rural areas of Albania rendering considerable help in the improvement of the equines-related situation, especially donkeys and mules considering their poor living conditions and sensitivity of members of these organizations. Assistance was direct and consisted of examining and providing therapeutic and regular prophylactic treatment for donkeys and mules at many collection points. During the present study, each season 52 (64.2), 23 (30.3), 38 (43.7) and 48 (52.2) individuals were found to have gastrointestinal parasite. These results further indicate that moderate-level parasitic infection exists among animals in Albania every season, notably in spring, summer and autumn. These data as mentioned below, reflect the level of prevalence of cyathostome infection. Of the large strongyles, Strongylus vulgaris was the only member of the genus found in this survey. Strongylus vulgaris is considered to be the most pathogenic nematode in the horse, as well as one of the most ubiquitous. The prevalence and pathogenicity of Strongylus vulgaris present special problems to the horse breeding industry; a single exposure to a contaminated pasture lead to death or severe clinical 42
illness in susceptible horses (6). Patterns of transmission vary greatly with climate and management. In the present study, Strongylus vulgaris was the most prevalent in summer 23%, followed by spring 17% and autumn 7%. The prepatent period of Strongylus vulgaris is approximately 6 months. This seasonal trend is related to the fact that equines would have little opportunity to pick up infective larvae during the late spring and hot and dry summer months because of high larval mortality on pastures. These findings suggest that a gradual increase in availability of larvae during autumn and early winter corresponds to increase in number of individuals infected with adult worms in spring and summer. The present study is the first in Albania that provides information on the seasonal pattern of the availability of infective larvae of Strongylus vulgaris on pastures. The pattern of transmission in Albania may be similar to that described in Moroco, a semi-arid area with a similar Mediterranean climate. In such climate characterized by mild wet winters and hot dry summers, the transmission from herbage was found to occur mostly in late autumn and winter. Developing larvae were found in the arteries during spring and summer, and sexually mature worms were found in the gut during summer and autumn (15). Forty-one percent of individuals in this study were infected with small strongyles. This prevalence is higher than that of the other gastrointestinal parasites found in the survey. This prevalence is consistent with that recently evidenced in various countries, proving that cyathostome populations have increased significantly in spite of the advent of effective anthelmintics (8, 9). Larval cyathostomiasis was recently identified as a major cause of verminous colic in horses (1). Small strongyle showed higher prevalence in autumn than either in summer or spring, and was less prevalent in winter. In Albania, environmental factors influenced the occurrence of equine strongyles more than the biotic factors such as age, sex, and breed (16). It appears that many equines may become infected during the warmer months of the year. This is in accordance with the seasonal variation in infective larvae on pasture in cool climates. A number of studies show that temperature is the main factor which determines the availability of infective larvae on pastures in temperate regions (2, 3, 4, 5, 6). Considering the prepatent periods that vary from 6 to 8 wks in small strongyles, the increase in pasture larval counts in late autumn resulted from development of worm eggs shed by equines in autumn rather than the emergence of pre-existing larvae from summer refugia as soil or fecal masses. No difference was noted in the prevalence of strongyles among different geographical regions. Animals from the plane areas had lower prevalence than animals from other geographical regions, but the difference was not statistically significant. A possible explanation for the similar prevalences in different geographical regions is the same grazing intensity of the animals. Consequently, pasture larval contamination and exposure to infective strongyle larvae are probably the same in different geographical regions. Veterinaria 59 (1-4), 37-45, Sarajevo 2010. 43
In regard with other parasitic species found in the previous surveys, their prevalence was much lower than strongyles, without any significant changes. Conclusion Cyathostomes are ubiquitous in Albania and are particularly common in young horses. It appears that problems with strongyle parasite most likely occur in animals that are not dewormed properly and lack care, unlike the riding horses who generally live in clean stables and receive more regular anthelmintic treatments. Furthermore, although the occurence of Strongylus vulgaris was found low, it is still a parasite that deserves attention and control in Albania. Acknowledgments We thank the numerous veterinarians and owners who made animals available for this study. This survey was part of a project made possible by research grant from Ministry of Education and Science of Albania and Ministry of Development of Greece. The excellent technical assistance of Mr. Edmond Agolli is gratefully acknowledged. REFERENCES 1. Church S, Kelly DF, Obwolo MJ. Diagnosis and successful treatment of diarrhea in horses caused by imature small strongyles apparently in susceptible to anthelmintics. Equine Vet J. 1986; 18: 401-403. 2. Courtney CH, Asquith RL. Seasonal changes in pasture infectivity by equine cyathostomes in north central Florida. Equine Vet J. 1985; 17:240-242. 3. Courtney CH.Seasonal transmission of equine cyathostomes in warm climates.vet Parasitol. 1999; 85: 173-177. 4. Craig TM, Bowen JM, Ludwig KG. Transmision of equine cyathostomes (Strongylidae) in Central Texas. Am J Vet Res. 1983; 44: 1867-1869. 5. Craig TM. Considerations for the control of equine cyathostomes in arid areas. Vet Parasitol. 1999; 85: 181-186. 6. English AW. The epidemiology of equine strongylosis in Southern Queensland. The bionomics of the free-living in faeces and on pasture. Aust Vet J. 1979 a; 55: 299-304. 44
7. Euzeby J, ed. Diagnostic Experimental des Helminthoses Animals. Livre 1. Edition Informations Techniques des Services Veterinaries Ministere de l Agriculture. France; 1981. 8. Herd RP, Gabel AA. Reduced efficacy of anthelmintics in young compared with adult horses. Equine Vet J. 1990; 22 (3): 164-169. 9. Herd RP. Equine parasite control-problems associated with intensive anthelmintic therapy. Equine Vet Edu. 1990 a; 2: 41-47. 10. Herd RP. The changing world of worms: the rise of the cyathostomes and the decline of Strongylus vulgaris. Compendium on Continuing Education for the Practicing Veterinarians. 1990 b; 12: 732-734. 11. Himonas CA. A fecal survey on the helminthiasis of equines. Hellenic Vet Medicine. 1968; 20 (2): 77-92. 12. Himonas CA, ed. Veterinary Parasitology. Thessaloniki, Greece; 1979. 13. Melitis E, Papastavro A, Nathanail TH. Abstracts of the 2nd Hellenic Veterinary Congress. 1981; 87 14. Nilsson O, Lindholm A, Christensson D. A field evaluation of anthelmintics in horses in Sweden. Vet Parasitol. 1989; 32 (2-3): 163-171. 15. Pandey VS. Seasonal prevalence of Strongylus vulgaris in the anterior mesenteric artery of the donkey in Moroco. Vet Parasitol. 1980; 7: 357-362. 16. Postoli R, Munguli C. Prevalenca e parazitëve të familjes Strongylidae në kuaj të rrethit të Tiranës. Shkenca Bujqësore. 2003; 3 (3): 72-76. 17. Reinemeyer CR. Small strongyles. Recent advances. Vet Clin North Am Equine Pract. 1986; 2: 281-312. 18. Sotiraki ST, Badouras AG, Himonas CA. A survey on the prevalence of internal parasites of equines in Macedonia and Thessalia-Greece. J Equine. Vet. Sc. 1997; 17(10): 50-552. 19. Soulsby EJL, ed. Helminths Arthropods and Protozoa of Domesticated Animals. Morning s veterinary helmintology and entomology. 6th ed. London (England): Balliere, Tindall and Casell; 1968. 20. Thienpont D, Rochette F, Vanparijs OFJ. Diagnosing Helminthiasis by Coprological Examination. Beerse (Belgium): Janssen Research Foundation; 1986. 21. Xiao L, Herd R P, Majevski GA. Comparative efficacy of moxidectin and ivermectin against hypobiotic and encysted cyathostome and other equine parasites. Vet Parasitol. 1994; 53: 83-90. 22. - -: ANON - Manual of Veterinary Parasitological Laboratory Techniques. Third ed. Ministry of Agriculture Fisheries and Food. London: 1986. pg. 24. Uredništvo primilo rukopis 24.03.2010. Veterinaria 59 (1-4), 37-45, Sarajevo 2010. 45