Abstract:Neospora caninum, an Apicomplexan parasite that can causes abortion, is responsible for considerable economic and reproductive losses in livestock. The purpose of the present study was to determine whether recombinant NcSRS2 is a suitable indirect ELISA antigen for determining specific immune response to N. caninum in sheep. A total of 441 serum samples were subjected to IFAT and rNcSRS2 based-ELISA, with both tests performing similarly. The sensitivity and specificity of indirect ELISA were 98.6 and 98.3%, re… Show more
“…Regarding N. caninum, the occurrence of 23% seropositivity in sheep from this region was also higher than the majority of data reported in different regions of Brazil, ranging from 3.2% in the southern region (Vogel et al, 2006) to 15% in the northeast region (Uzeda et al, 2007), except for a higher seroprevalence of 29% in Rondônia, in the Amazon region and 31-32% in Campo Grande, in the central region of the country (Andreotti et al, 2009). Although positive association was found between seropositivity for T. gondii and the age of the animals, such association was not found for N. caninum only, as previously reported by other studies (Figliuolo et al, 2004;Romanelli et al, 2007;Spilovská et al, 2009), suggesting that vertical transmission could occur in sheep farms, similar to bovine infections.…”
Toxoplasmosis and neosporosis have been recognized as economically important diseases with considerable impact on the livestock industry. Considering the scarce information on the occurrence of Toxoplasma gondii and Neospora caninum infections in sheep from Uberlândia, Minas Gerais State, Brazil, this study aimed to investigate the frequency of antibodies against these parasites in sheep sera from this region by using different serological methods. A total of 155 sheep serum samples were analyzed by the indirect fluorescence antibody test (IFAT) and enzyme-linked immunosorbent assay (ELISA) for the detection of IgG against T. gondii and N. caninum. Seroreactivity by IFAT showed 80% of samples with titers between 512 and 2048 for T. gondii (cutoff ≥ 64) and 78% presenting titers between 50 and 200 for N. caninum (cutoff ≥ 50). Seroreactivity by ELISA showed 75% of samples with ELISA index (EI) between 2.0 and 3.0 for T. gondii (cutoff ≥ 1.3) and 54% presenting EI between 1.3 and 2.0 for N. caninum (cut off ≥ 1.3). Discordant results by both tests were analyzed by immunoblot, resulting in a total seropositivity of 61% for T. gondii and 23% for N. caninum, with 41% to T. gondii only, 3% to N. caninum only, and 20% to both parasites. There was a significant positive association between seropositivity to T. gondii and age over one year (P<0.001), but such association was not found for N. caninum infection. In conclusion, as T. gondii and N. caninum infections are simultaneously present in sheep flocks of this region, it should be emphasized the importance to carry out a regular monitoring of Toxoplasma infection due to its high prevalence, its zoonotic potential and induction of reproductive disorders leading to economic losses. For neosporosis, sheep farmers should be instructed about the presence of the parasite in the flock, its risk factors and potential abortifacient role in sheep. Differential flock management could be valuable tool to establish the association of serological positivity and reproductive disease induced by N. caninum in sheep.
“…Regarding N. caninum, the occurrence of 23% seropositivity in sheep from this region was also higher than the majority of data reported in different regions of Brazil, ranging from 3.2% in the southern region (Vogel et al, 2006) to 15% in the northeast region (Uzeda et al, 2007), except for a higher seroprevalence of 29% in Rondônia, in the Amazon region and 31-32% in Campo Grande, in the central region of the country (Andreotti et al, 2009). Although positive association was found between seropositivity for T. gondii and the age of the animals, such association was not found for N. caninum only, as previously reported by other studies (Figliuolo et al, 2004;Romanelli et al, 2007;Spilovská et al, 2009), suggesting that vertical transmission could occur in sheep farms, similar to bovine infections.…”
Toxoplasmosis and neosporosis have been recognized as economically important diseases with considerable impact on the livestock industry. Considering the scarce information on the occurrence of Toxoplasma gondii and Neospora caninum infections in sheep from Uberlândia, Minas Gerais State, Brazil, this study aimed to investigate the frequency of antibodies against these parasites in sheep sera from this region by using different serological methods. A total of 155 sheep serum samples were analyzed by the indirect fluorescence antibody test (IFAT) and enzyme-linked immunosorbent assay (ELISA) for the detection of IgG against T. gondii and N. caninum. Seroreactivity by IFAT showed 80% of samples with titers between 512 and 2048 for T. gondii (cutoff ≥ 64) and 78% presenting titers between 50 and 200 for N. caninum (cutoff ≥ 50). Seroreactivity by ELISA showed 75% of samples with ELISA index (EI) between 2.0 and 3.0 for T. gondii (cutoff ≥ 1.3) and 54% presenting EI between 1.3 and 2.0 for N. caninum (cut off ≥ 1.3). Discordant results by both tests were analyzed by immunoblot, resulting in a total seropositivity of 61% for T. gondii and 23% for N. caninum, with 41% to T. gondii only, 3% to N. caninum only, and 20% to both parasites. There was a significant positive association between seropositivity to T. gondii and age over one year (P<0.001), but such association was not found for N. caninum infection. In conclusion, as T. gondii and N. caninum infections are simultaneously present in sheep flocks of this region, it should be emphasized the importance to carry out a regular monitoring of Toxoplasma infection due to its high prevalence, its zoonotic potential and induction of reproductive disorders leading to economic losses. For neosporosis, sheep farmers should be instructed about the presence of the parasite in the flock, its risk factors and potential abortifacient role in sheep. Differential flock management could be valuable tool to establish the association of serological positivity and reproductive disease induced by N. caninum in sheep.
“…Among the studies conducted in Brazil with identical techniques and cut-off points, similar results were found by Faria et al (2010) in Alagoas (9.6%) and Munhóz et al (2010) in São Paulo (13.9%). However, the prevalence verified in this study was higher than the rates identified by Salaberry et al (2010) in Minas Gerais (8.1%) and Figliuolo et al (2004) in São Paulo (9.2%), and lower than the rates found by Andreotti et al (2009) in farms in the city of Campo Grande, central-western Brazil (30.8%), by Rossi et al (2011) in Minas Gerais (47.1%) and by Tembue et al (2011) in Pernambuco (64.2%). Variations by location might be related to differences in the region, climate, animal age, sample size (Dubey et al, 2011), production systems (Melo et al, 2001), or even pathogenic synergism (Melo et al, 2004).…”
The aim of this study was to determine the prevalence and factors associated with the occurrence of antibodies against Neospora caninum in sheep from Sergipe, northeastern Brazil. A total of 932 sheep serum samples from 54 properties in 19 municipalities from the State of Sergipe, Brazil were collected and assayed using an indirect fluorescent antibody test (IFAT) to assess antibodies against N. caninum. A cutoff point of 1:50 was adopted and results showed that 12.45% (116/932) of sheep were serum-reactive. Based on an unconditional logistic regression, the presence of dogs on the property was associated with protection (OR= 0.323), whereas the use of exchanged or borrowed breeding males was associated with infection (OR= 22.287). These results indicate that the occurrence of antibodies against N. caninum is endemic in the State municipalities.
“…These values were used to calculate the individual-level true seroprevalence according to Noordhuizen et al (2001). SE and SP of N. caninum ELISA were 98.6% and 98.3%, respectively (Andreotti et al, 2009). For calculating the herd-level true seroprevalence, the test SE and SP were adjusted from individual-to herdlevel using the Herdacc program (Jordan and McEwen, 1998), for a median herd size of 73 animals, herd cut-off value of one animal positive indicating a positive herd and 12-28 animals sampled per herd.…”
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