Estonian University of Life Sciences, Institute of Veterinary Medicine and Animal Sciences, Kreutzwaldi 62, 51014 Tartu, Estonia.
Vet Parasitol. 2012 Nov 23;190(1-2):43-50. doi: 10.1016/j.vetpar.2012.05.021. Epub 2012 Jun 1.
Cows infected with the tissue parasite Neospora caninum (Nc) are more likely to abort or give birth to calves with neurological disorders. The known infection routes are transplacentally and by consumption of oocysts shed by the definitive host, the dog. It has been hypothesised, that dormant stages of persistent Nc infection may be reactivated by immunosuppression mechanisms such as pathogenic invasions as bovine herpes virus 1 (BHV1) and bovine virus diarrhoea virus (BVDV). The study was set to give the first prevalence data on Nc from Estonian dairy herds in both animal as well as herd level. In addition, association between herd size and Nc, and association of Nc with abortion incidence (Ab), stillbirth incidence (Sb), insemination index (II), and calving interval (CaI) in the presence of BHV1 and BVDV was studied. Blood samples from 1973 animals from 100 herds were collected in 2006-2008, and 320 bulk tank milk (BTM) samples were collected in 2007. Antibodies against Nc was found in 2.5 ± 0.4% (95% CI) of the animals and at least one positive animal was found in 37.0 ± 4.7% (95% CI) of the herds. In addition, Nc antibodies were detected in 16.3 ± 2.0% (95% CI) of the tested BTM. Large herds (≥ 200 animals) were less likely to have seropositive animals for Nc. Logistic regression models showed that herds with more than one animal seropositive for Nc had significantly higher odds ratio of abortion incidence (OR: 11.92, 1.18-120.18 95% CI, p=0.036) and tendency of having more stillbirths (OR: 5.52, 0.87-35.02 95% CI, p=0.07). On the other hand one Nc seropostive cow in the herd was associated with lower odds ratio (OR: 0.22, 0.05-0.91 95% CI, p=0.04) of higher calving intervals. Estonian prevalence results reflect observations in the region. No evidence was found of the pathogens were affecting fertility variables through interactions but independently BHV1 and Nc had an impact on the abortion.
奶牛感染组织寄生虫 Neospora caninum（Nc）更容易流产或产下患有神经障碍的小牛。已知的感染途径是通过胎盘和食用终宿主狗排出的卵囊。据推测，潜伏的 Nc 感染可能会被免疫抑制机制重新激活，如牛疱疹病毒 1（BHV1）和牛病毒性腹泻病毒（BVDV）等病原体入侵。本研究旨在首次提供爱沙尼亚奶牛场动物和畜群水平上的 Nc 流行率数据。此外，还研究了畜群规模与 Nc 的关系，以及在存在 BHV1 和 BVDV 的情况下，Nc 与流产发生率（Ab）、死产发生率（Sb）、配种指数（II）和产犊间隔（CaI）的关系。2006-2008 年，从 100 个畜群中采集了 1973 只动物的血液样本，2007 年采集了 320 个奶样。在 2.5±0.4%（95%置信区间）的动物中发现了针对 Nc 的抗体，在 37.0±4.7%（95%置信区间）的畜群中至少发现了一个阳性动物。此外，在 16.3±2.0%（95%置信区间）的检测奶样中检测到了 Nc 抗体。大型畜群（≥200 头）的 Nc 血清阳性动物比例较低。逻辑回归模型显示，畜群中 Nc 血清阳性动物数量超过一只的动物流产发生率（OR：11.92，1.18-120.18 95%置信区间，p=0.036）和死产发生率（OR：5.52，0.87-35.02 95%置信区间，p=0.07）的比值更高。另一方面，畜群中每出现一只 Nc 血清阳性奶牛，产犊间隔的比值就会降低（OR：0.22，0.05-0.91 95%置信区间，p=0.04）。爱沙尼亚的流行率结果反映了该地区的观察结果。没有证据表明这些病原体通过相互作用影响了生育力变量，但 BHV1 和 Nc 确实独立地对流产产生了影响。
