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Detection of Blastocystis sp. in pigs in Aragon (Spain)
veterinary parasitology ELSEVIER
Veterinary Parasitology56 ( 1995) 345-348
Short c o m m u n i c a t i o n
Detection of Blastocystis sp. in pigs in Aragon ( Spain ) J. Quilez a'*, A. Clavel b, C. Sanchez-Acedo", A.C. Causape a "Department ofAnimal Pathology, Parasitologyand ParasiticDiseases, Facultyof Veterinary Medicine, Universityof Zaragoza, C/MiguelServet, 177, Zaragoza 50013, Spain bDepartmentof Microbiology, Facultyof Medicine, Universityof Zaragoza, Spain Accepted 12 April 1994
Abstract
Infection by Blastocystis sp. has been detected for the first time in pigs in Spain. Detection was carried out by the ethyl acetate-formalin concentration method and direct microscopy. Vacuolated cells ofBlastocystis sp. were found in stool samples from 27 of 360 pigs examined (7.5%). The protozoan was present on nine of 17 pig farms studied ( 53%). Infected pigs ranged from l month old to adults, but the organism was most frequent in 1-2 month old (18.4%) and 2-6 month old pigs (15.4%). No correlation was found between Blastocystis sp. infection and occurrence of diarrhoea in pigs.
Keywords:Blastocystissp.; Pig-Protozoa; Epidemiology-Protozoa
1. Introduction Blastocystis hominis is a protozoan parasite commonly found in the human gut. Some authors conclude that it is a commensal (Miller and Minshew, 1988 ) while other studies suggest that it is an agent of diarrhoeal diasease in humans and especially if present in large numbers (cit. Zierdt, 1991 ). However, Blastocystis sp. has also been identified in some animal species, including chickens and ostriches (Yamada et al., 1987; Belova and Kostenko, 1990), geese (Belova, 1992a), turkeys (Belova, 1992b), reptiles (Teow et al., 1992), ducks (Belova, 1991 ) and recently, from cockroaches (Zaman et al., 1993). Infection has also been reported in pigs and monkeys suffering from diarrhoea (Burden et al., 1978/ 1979; McClure et al., 1980; Pakandl, 1991 ). * Corresponding author. 0304-4017/95/$09.50 © 1995 ElsevierScienceB.V. All rights reserved SSD10304-4017 (94) 00682-3
346
J. Quilez et aL / VeterinaryParasitology 56 (1995) 345-348
The present paper is the first report on the presence of Blastocystis sp. in pigs in Spain.
2. Materials and methods From January 1992 to July 1993, stool samples from 360 pigs with or without symptoms of enteric disease selected at random from 17 farms throughout Aragon (northeast Spain), were examined for the presence of gastrointestinal parasites. Faecal specimens were concentrated by a modified Ritchie formalin-ethyl acetate sedimentation method and examined by light microscopy using wet and iodine-stained preparations. Ziehl-Neelsen modified technique (Henriksen and Pohlenz, 1981 ) was used to screen for Cryptosporidium ooeysts. When Blastocystis sp. cells were detected, size range and shape were recorded. Large, moderate and small numbers of Blastocystis sp. were recorded when over 5, 1-5 or less than 1 cell, respectively, were found per 40)< field.
3. Results Vacuolated cells of Blastocystis sp. were found in stool samples from 27 pigs (7.5%). The organism was present on nine of 17 pig farms studied (53%). The vacuolar forms were generally spherical in shape, hut a morphologic heterogeneity was observed. The cells had a large central body within a thin peripheral layer of cytoplasm containing nuclei and some inclusions. The central body was usually empty, but some cells contained an inclusion. The overall size of Blastocystis sp. organisms ranged from 6 to 15 am, with a median of 7/~m. Large numbers of Blastocystis cells were found in one pig, moderate numbers in six and small numbers in 20. Infected pigs ranged from 1 month old to adults, but the protozoan was most frequent in 1-2 month old (18.4%) and 2-6 month old pigs (15.4%). None of the 23 suckling pigs up to 30 days old excreted Blastocystis sp. (Table 1 ). Table 1 Agerange of pigs infectedand numbers of Blastocystis sp. cellsdetected Age
< 1 month 1-2 months 2-6 months Adults Total
Infected/studied
0/23 (0%) 9/49 (18.4%) 12/78 (15.4%) 6/210 (2.8%) 27/360 (7.5%)
Number of cellsper 40 × field <1
1-5
>5
0 7 8 5 20
0 2 3 1 6
0 0 1 0 1
J. Quilez et al. / Veterinary Parasitology 56 (1995) 345-348
347
Diarrhoea, one of the most frequent symptoms in humans infected with Blastocystis hominis, was present in two weaned pigs 6 weeks of age, with small numbers of Blastocystis sp. in their faeces. One of them was also harboring Cryptosporidium parvum, but examinations for bacterial or viral enteritis were not performed. A total of 55.5% of pigs harbouring Blastocystis organisms were also excreting Cryptosporidium parvum oocysts.
4. Discussion
Blastocystis sp. has been found in a wide range of hosts, including birds, reptiles and mammals (Boreham and Stenzel, 1993). It is questionable whether Blastocystis sp., in unrelated hosts, represents only one species. New species have provisionally been described using ultrastructural studies and karyotypic patterns: Blastocystis galli in chickens (Belova and Kostenko, 1990), Blastocystis anatis in ducks (Belova, 1991 ), Blastocystis anseri in domestic geese (Belova, 1992a) and Blastocystis lapemi from a sea-snake (Teow et al., 1991 ). However, Phillips and Zierdt (1976) have successfully infected mice with Blastocystis sp. from pigs and porcine strains of Blastocystis sp. were infective to laboratory mice and gerbils, indicating a low host specificity of the protozoan (Pakandl, 1992 ). Burden (1976) first published on Blastocystis sp. infection in pigs. Burden et al. (1978/1979) found the organism on each of the five pig farms visited and reported a high prevalence (60%), recording usually low numbers of Blastocystis sp. cells from the stool samples. Pakandl ( 1991 ), using cultivation in modified LES nutrient broth with horse serum, has also determined the occurrence of Blastocystis sp. in pigs, reporting the infection from 3 days of age to adults with a prevalence between 68 and 93% according to age. They also detected the organism in 22 of 30 stool samples from wild pigs (Sus scrofa). Our results indicate that the prevalence is not so high in our area (7.5%) but it was higher in 1-2 month old weaned piglets (18.4%) and 2-6 month old fattening pigs (15.4%) compared with older pigs (2.8%). Pakandl ( 1991 ) has reported a high prevalence in suckling piglets from the age of 3 days. We have not found the parasite in any ofthe 23 suckling pigs. According to our results Blastocystis sp. is not a cause of diarrhoea in pigs with an intensity of infection of over 5 cells per 40 × field. Burden et al. (1978/1979) reported high numbers of organisms only in those pigs suffering from diarrhoea, but they concluded that there is no evidence to suggest that Blastocystis has a pathogenic role. Pakandl ( 1991 ) has detected infections of high density, where up to 8 Blastocystis sp. cells were recorded per 100 × field and he has not found any correlation between intensity of Blastocystis infection in pigs and the occurrence of diarrhoea.
348
J. Quilez et al. / Veterinary Parasitology 56 (1995) 345-348
Acknowledgements This study has been supported by a grant (PCM 32-91 ) of the Diputaci6n General de Arag6n, Spain. References Beiova, D.M., 1991. Blastocystis anatis sp. nov. (Rhizopoda, Lobosea) from domestic ducks. Zool. Zh., 70: 5-10. (In Russian, with English abstract.) Belova, L.M., 1992a. Blastocystis anseri (Protista: Rhizopoda), a new species from domestic geese. Parazitologiya, 26: 80--82. (In Russian, with English abstract. ) Beiova, L.M., 1992b. A finding ofBlastocystis galli (Rhizopoda: Lobosea) in domestic turkeys. Parazitologiya, 26: 166-168. (In Russian, with English abstract. ) Belova, L.M. and Kostenko, L.A., 1990. Blastocystis galli sp. nov. (Protista: Rhizopoda) from the intestine of chickens. Parazitologiya, 24:164-168. (In Russian, with English abstract.) Boreham, P.F.L. and Stenzel, D.J., 1993. Blastocystis in humans and animals: morphology, biology and epizootiology. Adv. Parasitol., 32: 1-70. Burden, D.J., 1976. Blastocystis sp.--a parasite of pigs. Parasitology, 73: iv-v. Burden, D.J., Anger, H.S. and Hammer, N.C., 1978/1979. Biastocystis sp. infection in pigs. Vet. Microbiol., 3: 227-234. Henriksen, S.A. and Pohlenz, J.F.L., 1981. Staining of cryptosporidia by a modified Ziehl-Neelsen technique. Acta. Vet. Seand., 22: 594-596. McClure, H.M., Strobert, E.A. and Healy, G.R., 1980. Blastocystis hominis in a pig-tailed macaque: a potential enteric pathogen for non-human primates. Lab. Anim. Sci., 30: 890-894. Miller, R.A. and Minshew, B.H., 1988. Blastocystis hominid, an organism in search of a disease. Rev. Infect. Dis., 10: 930-938. Pakandl, M., 1991. Occurrence ofBlastocystis sp. in pigs. Folia Parasitol., 38: 297-301. Pakandl, M., 1992. An experimental transmission of porcine strains of Blastocystis sp. in the laboratory mice and gerbils. Folia Parasitol., 39: 383-386. Phillips, B.P. and Zierdt, C.H., 1976. Blastocystis hominis: Pathogenic potential in human patients and in gnotobiotes. Exp. Parasitol., 39: 358-364. Teow, W.L., Zaman, V., Ng, G.C., Chan, Y.C., Yap, E.H., Howe, J., Gopalakrishnakone, P. and Singh, M., 1991. A Blastocystis species from the sea-snake, Lapemis hardwicldi (Serpentes: Hydrophiidae). Int. J. Parasitol., 21: 723-726. Teow, W.L., Ng, G.C., Chart, P.P., Chan, Y.C., Yap, E.H., Zaman, V. and Singh, M., 1992. A survey of Blastocystis in reptiles. Parasitol. Res., 78: 453-455. Yamada, H., Yoshikawa, H., Tegoshi, T., Matsumoto, Y., Yoshikawa, T., Shiota, T. and Yoshida, Y., 1987. Light microscopical study of Blastocystis spp. in monkeys and fowls. Parasitol. Res., 73: 527-531. Zaman, V., Ng, G.C., Suresh, K., Yap, E.H. and Singh, M., 1993. Isolation of Blastocystis from the cockroach (Dictyoptera: Blattidae). Parasitol. Res., 79: 73-74. Zierdt, C.H., 1991. Blastocystis hominis--Past and future. Clin. Microbiol. Rev., 4:61-79.
Veterinary Parasitology56 ( 1995) 345-348
Short c o m m u n i c a t i o n
Detection of Blastocystis sp. in pigs in Aragon ( Spain ) J. Quilez a'*, A. Clavel b, C. Sanchez-Acedo", A.C. Causape a "Department ofAnimal Pathology, Parasitologyand ParasiticDiseases, Facultyof Veterinary Medicine, Universityof Zaragoza, C/MiguelServet, 177, Zaragoza 50013, Spain bDepartmentof Microbiology, Facultyof Medicine, Universityof Zaragoza, Spain Accepted 12 April 1994
Abstract
Infection by Blastocystis sp. has been detected for the first time in pigs in Spain. Detection was carried out by the ethyl acetate-formalin concentration method and direct microscopy. Vacuolated cells ofBlastocystis sp. were found in stool samples from 27 of 360 pigs examined (7.5%). The protozoan was present on nine of 17 pig farms studied ( 53%). Infected pigs ranged from l month old to adults, but the organism was most frequent in 1-2 month old (18.4%) and 2-6 month old pigs (15.4%). No correlation was found between Blastocystis sp. infection and occurrence of diarrhoea in pigs.
Keywords:Blastocystissp.; Pig-Protozoa; Epidemiology-Protozoa
1. Introduction Blastocystis hominis is a protozoan parasite commonly found in the human gut. Some authors conclude that it is a commensal (Miller and Minshew, 1988 ) while other studies suggest that it is an agent of diarrhoeal diasease in humans and especially if present in large numbers (cit. Zierdt, 1991 ). However, Blastocystis sp. has also been identified in some animal species, including chickens and ostriches (Yamada et al., 1987; Belova and Kostenko, 1990), geese (Belova, 1992a), turkeys (Belova, 1992b), reptiles (Teow et al., 1992), ducks (Belova, 1991 ) and recently, from cockroaches (Zaman et al., 1993). Infection has also been reported in pigs and monkeys suffering from diarrhoea (Burden et al., 1978/ 1979; McClure et al., 1980; Pakandl, 1991 ). * Corresponding author. 0304-4017/95/$09.50 © 1995 ElsevierScienceB.V. All rights reserved SSD10304-4017 (94) 00682-3
346
J. Quilez et aL / VeterinaryParasitology 56 (1995) 345-348
The present paper is the first report on the presence of Blastocystis sp. in pigs in Spain.
2. Materials and methods From January 1992 to July 1993, stool samples from 360 pigs with or without symptoms of enteric disease selected at random from 17 farms throughout Aragon (northeast Spain), were examined for the presence of gastrointestinal parasites. Faecal specimens were concentrated by a modified Ritchie formalin-ethyl acetate sedimentation method and examined by light microscopy using wet and iodine-stained preparations. Ziehl-Neelsen modified technique (Henriksen and Pohlenz, 1981 ) was used to screen for Cryptosporidium ooeysts. When Blastocystis sp. cells were detected, size range and shape were recorded. Large, moderate and small numbers of Blastocystis sp. were recorded when over 5, 1-5 or less than 1 cell, respectively, were found per 40)< field.
3. Results Vacuolated cells of Blastocystis sp. were found in stool samples from 27 pigs (7.5%). The organism was present on nine of 17 pig farms studied (53%). The vacuolar forms were generally spherical in shape, hut a morphologic heterogeneity was observed. The cells had a large central body within a thin peripheral layer of cytoplasm containing nuclei and some inclusions. The central body was usually empty, but some cells contained an inclusion. The overall size of Blastocystis sp. organisms ranged from 6 to 15 am, with a median of 7/~m. Large numbers of Blastocystis cells were found in one pig, moderate numbers in six and small numbers in 20. Infected pigs ranged from 1 month old to adults, but the protozoan was most frequent in 1-2 month old (18.4%) and 2-6 month old pigs (15.4%). None of the 23 suckling pigs up to 30 days old excreted Blastocystis sp. (Table 1 ). Table 1 Agerange of pigs infectedand numbers of Blastocystis sp. cellsdetected Age
< 1 month 1-2 months 2-6 months Adults Total
Infected/studied
0/23 (0%) 9/49 (18.4%) 12/78 (15.4%) 6/210 (2.8%) 27/360 (7.5%)
Number of cellsper 40 × field <1
1-5
>5
0 7 8 5 20
0 2 3 1 6
0 0 1 0 1
J. Quilez et al. / Veterinary Parasitology 56 (1995) 345-348
347
Diarrhoea, one of the most frequent symptoms in humans infected with Blastocystis hominis, was present in two weaned pigs 6 weeks of age, with small numbers of Blastocystis sp. in their faeces. One of them was also harboring Cryptosporidium parvum, but examinations for bacterial or viral enteritis were not performed. A total of 55.5% of pigs harbouring Blastocystis organisms were also excreting Cryptosporidium parvum oocysts.
4. Discussion
Blastocystis sp. has been found in a wide range of hosts, including birds, reptiles and mammals (Boreham and Stenzel, 1993). It is questionable whether Blastocystis sp., in unrelated hosts, represents only one species. New species have provisionally been described using ultrastructural studies and karyotypic patterns: Blastocystis galli in chickens (Belova and Kostenko, 1990), Blastocystis anatis in ducks (Belova, 1991 ), Blastocystis anseri in domestic geese (Belova, 1992a) and Blastocystis lapemi from a sea-snake (Teow et al., 1991 ). However, Phillips and Zierdt (1976) have successfully infected mice with Blastocystis sp. from pigs and porcine strains of Blastocystis sp. were infective to laboratory mice and gerbils, indicating a low host specificity of the protozoan (Pakandl, 1992 ). Burden (1976) first published on Blastocystis sp. infection in pigs. Burden et al. (1978/1979) found the organism on each of the five pig farms visited and reported a high prevalence (60%), recording usually low numbers of Blastocystis sp. cells from the stool samples. Pakandl ( 1991 ), using cultivation in modified LES nutrient broth with horse serum, has also determined the occurrence of Blastocystis sp. in pigs, reporting the infection from 3 days of age to adults with a prevalence between 68 and 93% according to age. They also detected the organism in 22 of 30 stool samples from wild pigs (Sus scrofa). Our results indicate that the prevalence is not so high in our area (7.5%) but it was higher in 1-2 month old weaned piglets (18.4%) and 2-6 month old fattening pigs (15.4%) compared with older pigs (2.8%). Pakandl ( 1991 ) has reported a high prevalence in suckling piglets from the age of 3 days. We have not found the parasite in any ofthe 23 suckling pigs. According to our results Blastocystis sp. is not a cause of diarrhoea in pigs with an intensity of infection of over 5 cells per 40 × field. Burden et al. (1978/1979) reported high numbers of organisms only in those pigs suffering from diarrhoea, but they concluded that there is no evidence to suggest that Blastocystis has a pathogenic role. Pakandl ( 1991 ) has detected infections of high density, where up to 8 Blastocystis sp. cells were recorded per 100 × field and he has not found any correlation between intensity of Blastocystis infection in pigs and the occurrence of diarrhoea.
348
J. Quilez et al. / Veterinary Parasitology 56 (1995) 345-348
Acknowledgements This study has been supported by a grant (PCM 32-91 ) of the Diputaci6n General de Arag6n, Spain. References Beiova, D.M., 1991. Blastocystis anatis sp. nov. (Rhizopoda, Lobosea) from domestic ducks. Zool. Zh., 70: 5-10. (In Russian, with English abstract.) Belova, L.M., 1992a. Blastocystis anseri (Protista: Rhizopoda), a new species from domestic geese. Parazitologiya, 26: 80--82. (In Russian, with English abstract. ) Beiova, L.M., 1992b. A finding ofBlastocystis galli (Rhizopoda: Lobosea) in domestic turkeys. Parazitologiya, 26: 166-168. (In Russian, with English abstract. ) Belova, L.M. and Kostenko, L.A., 1990. Blastocystis galli sp. nov. (Protista: Rhizopoda) from the intestine of chickens. Parazitologiya, 24:164-168. (In Russian, with English abstract.) Boreham, P.F.L. and Stenzel, D.J., 1993. Blastocystis in humans and animals: morphology, biology and epizootiology. Adv. Parasitol., 32: 1-70. Burden, D.J., 1976. Blastocystis sp.--a parasite of pigs. Parasitology, 73: iv-v. Burden, D.J., Anger, H.S. and Hammer, N.C., 1978/1979. Biastocystis sp. infection in pigs. Vet. Microbiol., 3: 227-234. Henriksen, S.A. and Pohlenz, J.F.L., 1981. Staining of cryptosporidia by a modified Ziehl-Neelsen technique. Acta. Vet. Seand., 22: 594-596. McClure, H.M., Strobert, E.A. and Healy, G.R., 1980. Blastocystis hominis in a pig-tailed macaque: a potential enteric pathogen for non-human primates. Lab. Anim. Sci., 30: 890-894. Miller, R.A. and Minshew, B.H., 1988. Blastocystis hominid, an organism in search of a disease. Rev. Infect. Dis., 10: 930-938. Pakandl, M., 1991. Occurrence ofBlastocystis sp. in pigs. Folia Parasitol., 38: 297-301. Pakandl, M., 1992. An experimental transmission of porcine strains of Blastocystis sp. in the laboratory mice and gerbils. Folia Parasitol., 39: 383-386. Phillips, B.P. and Zierdt, C.H., 1976. Blastocystis hominis: Pathogenic potential in human patients and in gnotobiotes. Exp. Parasitol., 39: 358-364. Teow, W.L., Zaman, V., Ng, G.C., Chan, Y.C., Yap, E.H., Howe, J., Gopalakrishnakone, P. and Singh, M., 1991. A Blastocystis species from the sea-snake, Lapemis hardwicldi (Serpentes: Hydrophiidae). Int. J. Parasitol., 21: 723-726. Teow, W.L., Ng, G.C., Chart, P.P., Chan, Y.C., Yap, E.H., Zaman, V. and Singh, M., 1992. A survey of Blastocystis in reptiles. Parasitol. Res., 78: 453-455. Yamada, H., Yoshikawa, H., Tegoshi, T., Matsumoto, Y., Yoshikawa, T., Shiota, T. and Yoshida, Y., 1987. Light microscopical study of Blastocystis spp. in monkeys and fowls. Parasitol. Res., 73: 527-531. Zaman, V., Ng, G.C., Suresh, K., Yap, E.H. and Singh, M., 1993. Isolation of Blastocystis from the cockroach (Dictyoptera: Blattidae). Parasitol. Res., 79: 73-74. Zierdt, C.H., 1991. Blastocystis hominis--Past and future. Clin. Microbiol. Rev., 4:61-79.