Evaluation of Toxoplasma gondii and Neospora caninum infections in sheep from Uberlândia, Minas Gerais State, Brazil, by different serological methods.
ABSTRACT 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.
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ABSTRACT: The purpose of this study was to determine the seroprevalence of anti-N. caninum antibodies, the prevalence of the parasite's DNA in blood and to estimate the association between seroprevalence and potential risk factors in sheep herds in Aguascalientes, Mexico. A total of 324 blood samples were taken from 13 farms and tested using ELISA in order to detect N. caninum antibodies and nested PCR was used to determine the prevalence of the parasite's DNA in blood. The association between seroprevalence and some potential risk factors was estimated. The general seroprevalence reached 5.5% (18/324; 95% C.I. 3-8), ranging between 4 to 15% with the presence of seropositive animals in 61.5% of the farms; seroprevalence in ewes was 5.2% (15/286; 95% C.I. 3-8) while in rams it reached 7.9% (3/38; 95% C.I. 2-22). The prevalence of the parasite's DNA in blood was 25% (81/324; 95% C.I. 20-30), with a range from 7.7 to 50%, with 84.6% of the flock with at least one positive animal. Were identified as positive to both tests the 3% of the animals probed (10/324; 95% C.I. 1-5) of which nine were ewes and only one ram. The agreement between tests was k= 0.12. No association statistically significant was found between seroprevalence and the risk factors considered in this study.Small Ruminant Research 06/2014; · 1.10 Impact Factor
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ABSTRACT: Toxoplasma gondii is a zoonotic protozoan parasite which can cause significant disease and losses in livestock and wild animals. It is increasingly recognized as an important foodborne pathogen in a broad range of food animals and products. Effective control strategies require rapid, reliable and cost-effective detection methods for large scale surveys and diagnostic applications in a broad range of warm-blooded animals. To overcome one or more of these shortcomings in the currently available detection methods for T. gondii infection a non-species-specific protein A/G conjugate was used in the development of an indirect ELISA (ELISA-A/G) for the detection of IgG antibodies in serum samples obtained from experimentally infected pigs. The performance of the assay was evaluated using serum samples from pigs, cats, mice and seals with known positive or negative status for T. gondii infection. Results of the ELISA-A/G obtained with pig serum samples were compared with those generated by traditional ELISA using host specific IgG conjugate (ELISA-IgG), modified agglutination test (MAT) and Western blot analysis (WB). Using protein A/G conjugate, comparative analysis of results from 77 samples obtained from T. gondii infected pigs showed excellent agreement between the ELISA-A/G and in-house ELISA-IgG (0.917κ). Similar agreements were also observed when these samples were tested by a commercial ELISA kit (0.816κ), MAT (0.816κ) and WB (0.79κ). A total of 86 serum samples obtained from cats, mice and seals experimentally infected with T. gondii and tested by the ELISA-A/G as well as MAT for the presence of anti-Toxoplasma IgG antibodies yielded Kappa value of 1.0 for cats and mice and 0.79 for seals. These results show that the ELISA-A/G is a suitable method for serological detection of T. gondii infection in multiple host species and has the potential for testing samples from a broad range of domestic, wild, and aquatic mammalian host species. Simultaneous testing of samples from multiple host species on the same ELISA plate, and the use of multiple plates in a single run for large scale screening will enhance the cost effectiveness and speed of the test in the control and management of toxoplasmosis. This study also shows the effectiveness of the protein A/G conjugate in a modified WB assay for confirmation of T. gondii infection in mammalian hosts. Appropriate validation studies using field samples from various host species to validate the performance of ELISA-A/G is recommended prior to its application for diagnostic and surveillance programs.Veterinary Parasitology 12/2013; · 2.55 Impact Factor
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ABSTRACT: Eighteen mature ewes of the Mytilene breed and 18 mature Local- Damascus crossbred goats, seronegative for Toxoplasma gondii (T. gondii) by ELISA were used. All animals were mated after synchronization of estrus. On day 90 of pregnancy, animals were randomly assigned to 3 experimental groups; 6 ewes (S1) and 6 goats (G1) were orally inoculated by stomach tube with 1000 oocysts; 6 ewes (S2) and 6 goats (G2) were orally inoculated with a non-infected control inoculum. On day 140+2 of pregnancy, the remaining 6 ewes (S3) and 6 goats (G3) were inoculated by stomach tube with 3000 oocysts. Positive T. godii DNA was detected in 94% of fetal and maternal blood, 95% fetal tissue, 89% pre-colostral udder secretions and 12.5% milk samples using Polymerase Chain Reaction (PCR). Infected animals and their live newborns was seropositive (ELISA) until the end of the study. PCR was able to detect T. gondii DNA in maternal blood of infected animals 3-5 days before abortion occurred. This time period may be used to implement preventive and therapeutic measure to reduce abortion rate and associated economic losses. Since milk and milk products are important food sources in rural areas and in many cases it is used unpasteurized before consumption. The T. gondii DNA, detected by PCR in milk samples of infected animals, increases the possibility that the parasite is transmitted through consumption of unpasteurized milk which is a highly relevant result for public health considerations and providing valuable information for future research.Pakistan Veterinary Journal 07/2013; · 1.39 Impact Factor