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Occurrence of antibodies against Neospora caninum in water buffaloes (Bubalus bubalis) on four ranches in Corrientes province, Argentina
Available online at www.sciencedirect.com
Veterinary Parasitology 150 (2007) 155–158 www.elsevier.com/locate/vetpar
Short communication
Occurrence of antibodies against Neospora caninum in water buffaloes (Bubalus bubalis) on four ranches in Corrientes province, Argentina C.M. Campero a,*, A. Pe´rez b, D.P. Moore b, G. Crudeli c, D. Benitez d, M.G. Draghi d, D. Cano a, J.L. Konrad c, A.C. Odeo´n a a
Instituto Nacional de Tecnologı´a Agropecuaria (INTA), 7620 Balcarce, Argentina Consejo Nacional de Investigaciones Cientı´ficas y Te´cnicas (CONICET), Argentina c Facultad de Ciencias Veterinarias, Universidad Nacional del Nordeste (UNNE), Corrientes, Argentina d Instituto Nacional de Tecnologı´a Agropecuaria (INTA), Mercedes, Corrientes, Argentina b
Received 9 April 2007; received in revised form 5 September 2007; accepted 5 September 2007
Abstract The aim of the present work was to describe the occurrence of antibodies to Neospora caninum in water buffaloes on four ranches located in Corrientes province in the northeast of Argentina. Antibodies against N. caninum were determined in sera of 449 water buffaloes by using an indirect fluorescent antibody test (IFAT). A Bayesian logistic regression mixed model was used to quantify the strength of association between positive serological results to N. caninum and gender, age and category (calf, steer, heifer, cow) as risk factors. Antibody titers were found in 287 (64%) buffaloes. All ranches had seropositive animals. Age was more strongly associated with positive results to N. caninum (OR: 1.4; CI 95%: 0.86–2.22) than gender (OR: 1.02, CI 95%: 0.40–2.59) and category (OR: 0.88, CI 95%: 0.57–0.88). Results suggest a high exposure of water buffaloes to N. caninum by postnatal transmission in these four ranches located in Corrientes province, Argentina. Further studies are needed to quantify the consequences of Neospora-infections in the water buffalo industry. # 2007 Elsevier B.V. All rights reserved. Keywords: Neospora caninum; Bubalus bubalis; Argentina
1. Introduction Neospora caninum, a coccidian parasite that has domestic dogs and coyotes as its definitive hosts (McAllister et al., 1998; Gondim et al., 2004), causes serious disease in cattle and dogs worldwide (Dubey, 2003). Evidence of Neospora-infections has been reported in many other domestic and wild species
* Corresponding author at: Veterinary Pathology, INTA Balcarce, CC 276, 7620 Balcarce, Argentina. Tel.: +54 2266 439100x20; fax: +54 2266 439101. E-mail address: [email protected] (C.M. Campero). 0304-4017/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2007.09.002
including water buffaloes (Bubalus bubalis) (Dubey et al., 1998; Huong et al., 1998). Detection of antibodies to N. caninum in buffaloes has been reported in Brazil (Fujii et al., 2001; Gennari et al., 2005); Egypt (Dubey et al., 1998); Italy (Guarino et al., 2000) and Vietnam (Huong et al., 1998). Because different cut-off points were used in these studies, it is difficult to compare the seroprevalence of antibodies against N. caninum in these countries. The reported percentage of exposed animals varied from 0 (0/40) in China (Yu et al., 2007) to 70.9% (139/196) in Brazil (Gennari et al., 2005). According to national records, approximately 80,000 head of water buffalo are raised under extensive conditions in wet areas of the northeast of Argentina
156
C.M. Campero et al. / Veterinary Parasitology 150 (2007) 155–158
(NEA) (SAGPYA, 2007). Water buffalo are better adapted to wet tropical and subtropical environments than cattle. The buffalo industry is increasing in the NEA area, with an impact on the regional economy. Bovine neosporosis has been reported as a cause of abortions in dairy and beef cattle in Argentina (Campero et al., 1998, 2003; Moore et al., 2002, 2003). In contrast, N. caninum has not been investigated as a cause of abortion in water buffaloes in this country. The aim of this study was to determine the occurrence of antibodies to N. caninum in buffaloes from herds in the province of Corrientes, Argentina. 2. Materials and methods 2.1. Experimental animals and blood samples Blood samples were collected from the jugular vein from 449 Mediterranean and Murrah crossbreed water buffaloes (B. bubalis), from 1 to 20 years of age, from four ranches located in Corrientes province, Argentina. Approximately 40% of the buffalo population from each ranch was bled. The animals were divided into three age groups: <3 years, 3–5 years and >5 years. Data regarding gender and category (calf, steer, heifer, and cow) were also recorded when available. Reproductive parameters in the four buffalo herds were within the normal range suggested by SAGPYA (2007) having pregnancy rates of about 80%, calving rates of about 75% and weaning rates of >70% (data not shown). Sera were kept at 20 8C until analysis. 2.2. Serological analysis N. caninum antibody levels were measured by an indirect fluorescent antibody test (IFAT) (Fujii et al., 2001) on tachyzoite slides made with the NC-1 N. caninum strain (kindly provided by Dr. MC Venturini, La Plata Veterinary College, Argentina). Rabbit antibovine IgG labeled with fluorescein isothiocyanate (Sigma, St. Louis, MO) was used as conjugate. The samples were tested at a dilution of 1:100 (Rodrigues et al., 2004). Positive and negative control sera from buffalo were kindly provided by Dr. S.M. Gennari, Veterinary College, Sa˜o Paulo University, Brazil. The IFAT was considered to be positive when peripheral staining patterns typical of tachyzoites were observed. 2.3. Statistical analysis A Bayesian logistic regression mixed model was used to quantify the strength of the association between
positive serological results for N. caninum and gender (male, female), age (years), and category (calf, steer, heifer, cow) of the sampled animals. A hierarchical model was necessary because animals within the same herd are more likely to have a similar probability of being positive to N. caninum than animals in different herds. Risk factors (gender, age and category) were included into the model as fixed effects. A random effect was included to account for herd level factors not assessed in this study. We used diffuse prior distributions of the forms N(0,4) and N[0,d Gamma(0.5,0.0005)] for the regression coefficients and the random effects, respectively. The model was run using the Win-BUGS software (Spiegelhalter et al., 1996), with 20,000 iterations after 500 iterations were discarded. We used a stepwise procedure to successively include variables into the model. The odds ratio (OR), calculated as the exponent of the posterior distribution of the regression coefficients, was used to estimate the strength of the association between each factor and positive status to N. caninum. The combination of variables that resulted in the lowest value of the deviance inference criterion (DIC) was considered the model that best fit the data (Spiegelhalter et al., 2002). 3. Results The distribution of age groups was as follows: <3 years—56 animals, 3–5 years—227 animals, >5 years—166 animals. There were 437 females (209 cows, 228 heifers) and 12 males (10 steers and 2 calves with more than 6 months of age). Specific antibodies were found in 287 (64%) buffaloes. All farms had seropositive animals. The proportion of seropositive animals on each farm is shown in Table 1. The distribution of N. caninum seropositive animals according to age groups is shown in Fig. 1. Age was more strongly associated with positive results to N. caninum (OR: 1.4; CI 95%: 0.86–2.22) than gender (OR: 1.02, CI 95%: 0.40–2.59) and category (OR: 0.88, CI 95%: 0.57–0.88). Moreover, the model Table 1 Occurrence of antibodies by IFAT against N. caninum in water buffaloes on four ranches in Corrientes province, Argentina Farm
%Seropositive animals
Total
A B C D
56.5 63.7 75.5 60.6
115 138 102 94
C.M. Campero et al. / Veterinary Parasitology 150 (2007) 155–158
Fig. 1. Percentage of N. caninum seropositive buffaloes on four ranches located in Corrientes province, Argentina.
that best fit (DIC: 586.2) the serological status to N. caninum only included age as a covariate (OR: 1.3, CI 95%: 0.96–1.7), suggesting that age was the most important factor contributing to the serological status to N. caninum in the populations of buffaloes assessed in this study. 4. Discussion This report demonstrates a high exposure of water buffaloes to N. caninum in four ranches located in Corrientes province, Argentina. These results agree with those reported by Fujii et al. (2001) and Gennari et al. (2005) from Brazil, who found a prevalence of antibodies to N. caninum >60% in 222 and 196 water buffaloes, respectively using IFAT with a serum dilution of 1.25. When a serum dilution of 1:200 was used in IFAT, the prevalence of antibodies was 34.6% in 1377 animals tested in Italy (Guarino et al., 2000). Only 1.5% of 200 animals tested seropositive in Vietnam (Huong et al., 1998); however, a serum dilution of 1:640 was used in the IFAT. Because Neospora was isolated from 5 of 6 water buffalo testing seropositive by IFAT using a serum dilution of 1:100 (Rodrigues et al., 2004), this dilution factor was used in the present work. The probability of being seropositive to N. caninum increased 30% per year in the populations of buffaloes assessed in this study. Older animals are expected to have a higher probability of cumulative exposure to infectious agents compared with younger animals. No association between gender or category and serological status to N. caninum was detected, suggesting that the age association estimated in this study may simply be a reflection of the yearly increment in the probability of exposure to the parasitic oocysts. A similar association between seroprevalence of antibodies against N. caninum and age was found in buffalo populations from southern Italy (Guarino et al., 2000) and southeastern Brazil (Fujii et al., 2001). On the other hand, this
157
association was not found in water buffaloes from northern Brazil (Gennari et al., 2005). Although vertical transmission occurs in buffaloes (Rodrigues et al., 2005) and it is a frequent and efficient route of infection in cattle (Dubey, 2003), it is unclear which route of infection is most important in buffaloes. Finally, although two aborted buffalo foetuses showed non-suppurative encephalitis and non-suppurative myocarditis with Neospora-like cysts in their brains (Guarino et al., 2000), it is not clear whether N. caninum is a frequent agent of abortion in buffaloes. In this study, a high occurrence of antibodies against N. caninum was associated with normal reproductive records in all four ranches (data not shown). We have reported and identified N. caninum as a cause of bovine spontaneous abortions (Campero et al., 2003); however, no information exists concerning reproductive losses in buffaloes. Although more studies should be done to clarify the consequences of Neospora-infections in water buffalo, the epidemiological role of infected buffaloes and the relationship with bovine neosporosis should be also investigated. Acknowledgments Authors express their appreciation to Miss Marı´a R. Leunda and Mrs. Susana Mendez for their technical assistance. The authors also thank Dr. Solange M. Gennari from the Veterinary College, Sa˜o Paulo University, Brazil for kindly providing positive and negative control buffalo sera and Dr. Douglas C. Hodgins from the Department of Pathobiology, Ontario Veterinary College, University of Guelph, Canada for help in preparation of this paper. References Campero, C.M., Anderson, M.L., Conosciuto, G., Odriozola, H., Bretschneider, G., Poso, M.A., 1998. Neospora caninum associated abortion in a dairy herd in Argentina. Vet. Rec. 143, 228– 229. Campero, C.M., Moore, D.P., Odeo´n, A.C., Cipolla, A., Odriozola, E., 2003. Aetiology of bovine abortion in Argentina. Vet. Res. Commun. 27, 359–369. Dubey, J.P., 2003. Neosporosis in cattle. J. Parasitol. 89, 42–56. Dubey, J.P., Romand, S., Hilali, M., Kwok, O.C.H., Thullies, P., 1998. Seroprevalence of antibodies to Neospora caninum and Toxoplasma gondii in water buffaloes (Bubalus bubalis) from Egypt. Int. J. Parasitol. 28, 527–529. Fujii, T.U., Kasai, N., Nishi, S.M., Dubey, J.P., Gennari, S.M., 2001. Seroprevalence of Neospora caninum in female water buffaloes (Bubalus bubalis) from the southeastern region of Brazil. Vet. Parasitol. 99, 331–334. Gennari, S.M., Rodrigues, A.A.R., Viana, R.B., Cardoso, E.C., 2005. Occurrence of anti-Neospora caninum antibodies in water buffa-
158
C.M. Campero et al. / Veterinary Parasitology 150 (2007) 155–158
loes (Bubalus bubalis) from the Northern region of Brazil. Vet. Parasitol. 134, 169–171. Gondim, L.F.P., McAllister, M.M., Pitt, W.C., Zemlicka, D.E., 2004. Coyotes (Canis latrans) are definitive hosts of Neospora caninum. Int. J. Parasitol. 34, 159–161. Guarino, A., Fusco, G., Savini, G., Di Francesco, G., Cringoli, G., 2000. Neosporosis in water buffalo (Bubalus bubalis) in southern Italy. Vet. Parasitol. 91, 15–21. Huong, L.T.T., Ljungstrom, B.L., Uggla, A., Bjorkman, C., 1998. Prevalence of antibodies to Neospora caninum and Toxoplasma gondii in cattle and water buffaloes in southern Vietnam. Vet. Parasitol. 75, 53–57. McAllister, M.M., Dubey, J.P., Lindsay, D.S., Jolley, W.R., Wills, R.A., McGuire, A.M., 1998. Dogs are definitive hosts of Neospora caninum. Int. J. Parasitol. 28, 1473–1478. Moore, D.P., Campero, C.M., Odeo´n, A.C., Poso, M.A., Cano, D., Leunda, M.R., Basso, W., Venturini, M.C., Spa¨th, E., 2002. Seroepidemiology of beef and dairy herds and fetal study of Neospora caninum in Argentina. Vet. Parasitol. 107, 303– 316. Moore, D.P., Campero, C.M., Odeo´n, A.C., Chayer, R., Bianco, M.A., 2003. Reproductive losses due to Neospora caninum in a beef herd in Argentina. J. Vet. Med. B 50, 304–308.
Rodrigues, A.A.R., Gennari, S.M., Aguiar, D.M., Sreekumar, C., Hill, D.E., Miska, K., Vianna, M.C.B., Dubey, J.P., 2004. Shedding of Neospora caninum oocysts by dogs fed tissues from naturally infected water buffaloes (Bubalus bubalis) from Brazil. Vet. Parasitol. 124, 139–150. Rodrigues, A.A.R., Gennari, S.M., Paula, V.S.O., Aguiar, D.M., Fujii, T.U., Starke-Buzetti, W., Machado, R.Z., Dubey, J.P., 2005. Serological response to Neospora caninum in experimentally and naturally infected water buffaloes (Bubalis bubalis). Vet. Parasitol. 129, 21–24. SAGPYA (Secretarı´a de Agricultura Ganaderı´a, Pesca y Alimentacio´n), 2007. http://www.sagpya.mecon.gov.ar. Spiegelhalter, D., Thomas, A., Best, N., Gilks, W., 1996. BUGS: Bayesian inference using Gibbs sampling, version 0.50. MRC Biostatistics Unit: Cambridge. http://www.mrc-bsu.cam.ac.uk/ bugs/winbugs/contents.shtml. Spiegelhalter, D.J., Best, N., Carlin, B.P., van der Linde, A., 2002. Bayesian measures of model complexity and fit (with discussion). J. Roy. Statist. Soc. Ser. B 64, 583–639. Yu, J., Xia, Z., Liu, Q., Liu, J., Ding, J., Zhang, W., 2007. Seroepidemiology of Neospora caninum and Toxoplasma gondii in cattle and water buffaloes (Bubalus bubalis) in the People’s Republic of China. Vet. Parasitol. 143, 79–85.
Veterinary Parasitology 150 (2007) 155–158 www.elsevier.com/locate/vetpar
Short communication
Occurrence of antibodies against Neospora caninum in water buffaloes (Bubalus bubalis) on four ranches in Corrientes province, Argentina C.M. Campero a,*, A. Pe´rez b, D.P. Moore b, G. Crudeli c, D. Benitez d, M.G. Draghi d, D. Cano a, J.L. Konrad c, A.C. Odeo´n a a
Instituto Nacional de Tecnologı´a Agropecuaria (INTA), 7620 Balcarce, Argentina Consejo Nacional de Investigaciones Cientı´ficas y Te´cnicas (CONICET), Argentina c Facultad de Ciencias Veterinarias, Universidad Nacional del Nordeste (UNNE), Corrientes, Argentina d Instituto Nacional de Tecnologı´a Agropecuaria (INTA), Mercedes, Corrientes, Argentina b
Received 9 April 2007; received in revised form 5 September 2007; accepted 5 September 2007
Abstract The aim of the present work was to describe the occurrence of antibodies to Neospora caninum in water buffaloes on four ranches located in Corrientes province in the northeast of Argentina. Antibodies against N. caninum were determined in sera of 449 water buffaloes by using an indirect fluorescent antibody test (IFAT). A Bayesian logistic regression mixed model was used to quantify the strength of association between positive serological results to N. caninum and gender, age and category (calf, steer, heifer, cow) as risk factors. Antibody titers were found in 287 (64%) buffaloes. All ranches had seropositive animals. Age was more strongly associated with positive results to N. caninum (OR: 1.4; CI 95%: 0.86–2.22) than gender (OR: 1.02, CI 95%: 0.40–2.59) and category (OR: 0.88, CI 95%: 0.57–0.88). Results suggest a high exposure of water buffaloes to N. caninum by postnatal transmission in these four ranches located in Corrientes province, Argentina. Further studies are needed to quantify the consequences of Neospora-infections in the water buffalo industry. # 2007 Elsevier B.V. All rights reserved. Keywords: Neospora caninum; Bubalus bubalis; Argentina
1. Introduction Neospora caninum, a coccidian parasite that has domestic dogs and coyotes as its definitive hosts (McAllister et al., 1998; Gondim et al., 2004), causes serious disease in cattle and dogs worldwide (Dubey, 2003). Evidence of Neospora-infections has been reported in many other domestic and wild species
* Corresponding author at: Veterinary Pathology, INTA Balcarce, CC 276, 7620 Balcarce, Argentina. Tel.: +54 2266 439100x20; fax: +54 2266 439101. E-mail address: [email protected] (C.M. Campero). 0304-4017/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2007.09.002
including water buffaloes (Bubalus bubalis) (Dubey et al., 1998; Huong et al., 1998). Detection of antibodies to N. caninum in buffaloes has been reported in Brazil (Fujii et al., 2001; Gennari et al., 2005); Egypt (Dubey et al., 1998); Italy (Guarino et al., 2000) and Vietnam (Huong et al., 1998). Because different cut-off points were used in these studies, it is difficult to compare the seroprevalence of antibodies against N. caninum in these countries. The reported percentage of exposed animals varied from 0 (0/40) in China (Yu et al., 2007) to 70.9% (139/196) in Brazil (Gennari et al., 2005). According to national records, approximately 80,000 head of water buffalo are raised under extensive conditions in wet areas of the northeast of Argentina
156
C.M. Campero et al. / Veterinary Parasitology 150 (2007) 155–158
(NEA) (SAGPYA, 2007). Water buffalo are better adapted to wet tropical and subtropical environments than cattle. The buffalo industry is increasing in the NEA area, with an impact on the regional economy. Bovine neosporosis has been reported as a cause of abortions in dairy and beef cattle in Argentina (Campero et al., 1998, 2003; Moore et al., 2002, 2003). In contrast, N. caninum has not been investigated as a cause of abortion in water buffaloes in this country. The aim of this study was to determine the occurrence of antibodies to N. caninum in buffaloes from herds in the province of Corrientes, Argentina. 2. Materials and methods 2.1. Experimental animals and blood samples Blood samples were collected from the jugular vein from 449 Mediterranean and Murrah crossbreed water buffaloes (B. bubalis), from 1 to 20 years of age, from four ranches located in Corrientes province, Argentina. Approximately 40% of the buffalo population from each ranch was bled. The animals were divided into three age groups: <3 years, 3–5 years and >5 years. Data regarding gender and category (calf, steer, heifer, and cow) were also recorded when available. Reproductive parameters in the four buffalo herds were within the normal range suggested by SAGPYA (2007) having pregnancy rates of about 80%, calving rates of about 75% and weaning rates of >70% (data not shown). Sera were kept at 20 8C until analysis. 2.2. Serological analysis N. caninum antibody levels were measured by an indirect fluorescent antibody test (IFAT) (Fujii et al., 2001) on tachyzoite slides made with the NC-1 N. caninum strain (kindly provided by Dr. MC Venturini, La Plata Veterinary College, Argentina). Rabbit antibovine IgG labeled with fluorescein isothiocyanate (Sigma, St. Louis, MO) was used as conjugate. The samples were tested at a dilution of 1:100 (Rodrigues et al., 2004). Positive and negative control sera from buffalo were kindly provided by Dr. S.M. Gennari, Veterinary College, Sa˜o Paulo University, Brazil. The IFAT was considered to be positive when peripheral staining patterns typical of tachyzoites were observed. 2.3. Statistical analysis A Bayesian logistic regression mixed model was used to quantify the strength of the association between
positive serological results for N. caninum and gender (male, female), age (years), and category (calf, steer, heifer, cow) of the sampled animals. A hierarchical model was necessary because animals within the same herd are more likely to have a similar probability of being positive to N. caninum than animals in different herds. Risk factors (gender, age and category) were included into the model as fixed effects. A random effect was included to account for herd level factors not assessed in this study. We used diffuse prior distributions of the forms N(0,4) and N[0,d Gamma(0.5,0.0005)] for the regression coefficients and the random effects, respectively. The model was run using the Win-BUGS software (Spiegelhalter et al., 1996), with 20,000 iterations after 500 iterations were discarded. We used a stepwise procedure to successively include variables into the model. The odds ratio (OR), calculated as the exponent of the posterior distribution of the regression coefficients, was used to estimate the strength of the association between each factor and positive status to N. caninum. The combination of variables that resulted in the lowest value of the deviance inference criterion (DIC) was considered the model that best fit the data (Spiegelhalter et al., 2002). 3. Results The distribution of age groups was as follows: <3 years—56 animals, 3–5 years—227 animals, >5 years—166 animals. There were 437 females (209 cows, 228 heifers) and 12 males (10 steers and 2 calves with more than 6 months of age). Specific antibodies were found in 287 (64%) buffaloes. All farms had seropositive animals. The proportion of seropositive animals on each farm is shown in Table 1. The distribution of N. caninum seropositive animals according to age groups is shown in Fig. 1. Age was more strongly associated with positive results to N. caninum (OR: 1.4; CI 95%: 0.86–2.22) than gender (OR: 1.02, CI 95%: 0.40–2.59) and category (OR: 0.88, CI 95%: 0.57–0.88). Moreover, the model Table 1 Occurrence of antibodies by IFAT against N. caninum in water buffaloes on four ranches in Corrientes province, Argentina Farm
%Seropositive animals
Total
A B C D
56.5 63.7 75.5 60.6
115 138 102 94
C.M. Campero et al. / Veterinary Parasitology 150 (2007) 155–158
Fig. 1. Percentage of N. caninum seropositive buffaloes on four ranches located in Corrientes province, Argentina.
that best fit (DIC: 586.2) the serological status to N. caninum only included age as a covariate (OR: 1.3, CI 95%: 0.96–1.7), suggesting that age was the most important factor contributing to the serological status to N. caninum in the populations of buffaloes assessed in this study. 4. Discussion This report demonstrates a high exposure of water buffaloes to N. caninum in four ranches located in Corrientes province, Argentina. These results agree with those reported by Fujii et al. (2001) and Gennari et al. (2005) from Brazil, who found a prevalence of antibodies to N. caninum >60% in 222 and 196 water buffaloes, respectively using IFAT with a serum dilution of 1.25. When a serum dilution of 1:200 was used in IFAT, the prevalence of antibodies was 34.6% in 1377 animals tested in Italy (Guarino et al., 2000). Only 1.5% of 200 animals tested seropositive in Vietnam (Huong et al., 1998); however, a serum dilution of 1:640 was used in the IFAT. Because Neospora was isolated from 5 of 6 water buffalo testing seropositive by IFAT using a serum dilution of 1:100 (Rodrigues et al., 2004), this dilution factor was used in the present work. The probability of being seropositive to N. caninum increased 30% per year in the populations of buffaloes assessed in this study. Older animals are expected to have a higher probability of cumulative exposure to infectious agents compared with younger animals. No association between gender or category and serological status to N. caninum was detected, suggesting that the age association estimated in this study may simply be a reflection of the yearly increment in the probability of exposure to the parasitic oocysts. A similar association between seroprevalence of antibodies against N. caninum and age was found in buffalo populations from southern Italy (Guarino et al., 2000) and southeastern Brazil (Fujii et al., 2001). On the other hand, this
157
association was not found in water buffaloes from northern Brazil (Gennari et al., 2005). Although vertical transmission occurs in buffaloes (Rodrigues et al., 2005) and it is a frequent and efficient route of infection in cattle (Dubey, 2003), it is unclear which route of infection is most important in buffaloes. Finally, although two aborted buffalo foetuses showed non-suppurative encephalitis and non-suppurative myocarditis with Neospora-like cysts in their brains (Guarino et al., 2000), it is not clear whether N. caninum is a frequent agent of abortion in buffaloes. In this study, a high occurrence of antibodies against N. caninum was associated with normal reproductive records in all four ranches (data not shown). We have reported and identified N. caninum as a cause of bovine spontaneous abortions (Campero et al., 2003); however, no information exists concerning reproductive losses in buffaloes. Although more studies should be done to clarify the consequences of Neospora-infections in water buffalo, the epidemiological role of infected buffaloes and the relationship with bovine neosporosis should be also investigated. Acknowledgments Authors express their appreciation to Miss Marı´a R. Leunda and Mrs. Susana Mendez for their technical assistance. The authors also thank Dr. Solange M. Gennari from the Veterinary College, Sa˜o Paulo University, Brazil for kindly providing positive and negative control buffalo sera and Dr. Douglas C. Hodgins from the Department of Pathobiology, Ontario Veterinary College, University of Guelph, Canada for help in preparation of this paper. References Campero, C.M., Anderson, M.L., Conosciuto, G., Odriozola, H., Bretschneider, G., Poso, M.A., 1998. Neospora caninum associated abortion in a dairy herd in Argentina. Vet. Rec. 143, 228– 229. Campero, C.M., Moore, D.P., Odeo´n, A.C., Cipolla, A., Odriozola, E., 2003. Aetiology of bovine abortion in Argentina. Vet. Res. Commun. 27, 359–369. Dubey, J.P., 2003. Neosporosis in cattle. J. Parasitol. 89, 42–56. Dubey, J.P., Romand, S., Hilali, M., Kwok, O.C.H., Thullies, P., 1998. Seroprevalence of antibodies to Neospora caninum and Toxoplasma gondii in water buffaloes (Bubalus bubalis) from Egypt. Int. J. Parasitol. 28, 527–529. Fujii, T.U., Kasai, N., Nishi, S.M., Dubey, J.P., Gennari, S.M., 2001. Seroprevalence of Neospora caninum in female water buffaloes (Bubalus bubalis) from the southeastern region of Brazil. Vet. Parasitol. 99, 331–334. Gennari, S.M., Rodrigues, A.A.R., Viana, R.B., Cardoso, E.C., 2005. Occurrence of anti-Neospora caninum antibodies in water buffa-
158
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loes (Bubalus bubalis) from the Northern region of Brazil. Vet. Parasitol. 134, 169–171. Gondim, L.F.P., McAllister, M.M., Pitt, W.C., Zemlicka, D.E., 2004. Coyotes (Canis latrans) are definitive hosts of Neospora caninum. Int. J. Parasitol. 34, 159–161. Guarino, A., Fusco, G., Savini, G., Di Francesco, G., Cringoli, G., 2000. Neosporosis in water buffalo (Bubalus bubalis) in southern Italy. Vet. Parasitol. 91, 15–21. Huong, L.T.T., Ljungstrom, B.L., Uggla, A., Bjorkman, C., 1998. Prevalence of antibodies to Neospora caninum and Toxoplasma gondii in cattle and water buffaloes in southern Vietnam. Vet. Parasitol. 75, 53–57. McAllister, M.M., Dubey, J.P., Lindsay, D.S., Jolley, W.R., Wills, R.A., McGuire, A.M., 1998. Dogs are definitive hosts of Neospora caninum. Int. J. Parasitol. 28, 1473–1478. Moore, D.P., Campero, C.M., Odeo´n, A.C., Poso, M.A., Cano, D., Leunda, M.R., Basso, W., Venturini, M.C., Spa¨th, E., 2002. Seroepidemiology of beef and dairy herds and fetal study of Neospora caninum in Argentina. Vet. Parasitol. 107, 303– 316. Moore, D.P., Campero, C.M., Odeo´n, A.C., Chayer, R., Bianco, M.A., 2003. Reproductive losses due to Neospora caninum in a beef herd in Argentina. J. Vet. Med. B 50, 304–308.
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