Laboratório de Imunoparasitologia, Instituto de Ciências Biomédicas, Universidade Federal de Uberlândia, Av. Pará 1720, 38400-902 Uberlândia, MG, Brazil.
Vet Parasitol. 2011 Feb 10;175(3-4):252-9. doi: 10.1016/j.vetpar.2010.10.017. Epub 2010 Oct 16.
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.
弓形体病和新孢子虫病已被认为是对畜牧业具有重要经济影响的疾病。考虑到巴西米纳斯吉拉斯州乌贝兰迪亚地区绵羊中弓形虫和新孢子虫感染的发生信息匮乏，本研究旨在通过使用不同的血清学方法来调查该地区绵羊血清中针对这些寄生虫的抗体频率。共分析了 155 份绵羊血清样本，通过间接荧光抗体试验（IFAT）和酶联免疫吸附试验（ELISA）检测针对弓形虫和新孢子虫的 IgG。IFAT 的血清反应性显示，80%的样本对弓形虫的滴度在 512 到 2048 之间（临界值≥64），78%的样本对新孢子虫的滴度在 50 到 200 之间（临界值≥50）。ELISA 的血清反应性显示，75%的样本的 ELISA 指数（EI）在 2.0 到 3.0 之间（临界值≥1.3），54%的样本的 EI 在 1.3 到 2.0 之间（临界值≥1.3）。对两种检测方法的不一致结果进行免疫印迹分析，结果总弓形虫血清阳性率为 61%，新孢子虫血清阳性率为 23%，其中仅 41%为弓形虫，3%为新孢子虫，20%为两种寄生虫。弓形虫血清阳性与 1 岁以上年龄之间存在显著正相关（P<0.001），但未发现新孢子虫感染有这种关联。总之，由于该地区绵羊群中同时存在弓形虫和新孢子虫感染，应强调定期监测弓形虫感染的重要性，因为其高流行率、人畜共患潜力以及诱导生殖障碍导致经济损失。对于新孢子虫病，应向绵羊养殖户说明寄生虫在羊群中的存在、其危险因素以及对绵羊的潜在流产作用。对羊群进行差异化管理可能是确定新孢子虫引起的血清阳性与绵羊生殖疾病之间关联的有用工具。
