Evaluation of Toxoplasma gondii and Neospora caninum infections in sheep from Uberlândia, Minas Gerais State, Brazil, by different serological methods

AbstractToxoplasmosis 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