Hall C A, Reichel M P, Ellis J T
Novartis Animal Health Australasia Pty Ltd., Yarrandoo R&D Centre, 245 Western Road, Kemps Creek, NSW 2178, Australia.
Vet Parasitol. 2005 Mar 31;128(3-4):231-41. doi: 10.1016/j.vetpar.2004.12.012.
To determine the contribution of Neospora caninum to abortions on a dairy farm in NSW (Australia), determine the mode of transmission and develop and trial a control option for infection.
Two whole herd bleeds were conducted 12 months apart and the association between serological status and abortion events were calculated for a number of bovine abortifacients. Family trees were constructed for N. caninum seropositive cattle in the herd. Some N. caninum seropositive cows were culled from the herd and no female offspring was retained from seropositive cows.
At the first whole-herd bleed in December 2002 a seroprevalence of 10.2% for N. caninum infection was detected. Cows with N. caninum infection were 13 times more likely to abort than uninfected ones. Seventy-five percent of seropositive animals in the herd were related, suggesting a high degree of congenital infection/transmission. Only 15% of infections were likely to be postnatally acquired. Selective culling of seropositive cows and not breeding from them reduced the number of seropositive animals. Only one newly sero-converted cow was detected at the second whole-herd bleed 12 months later.
Seroepidemiological approaches were able to establish a high degree of association between N. caninum infection and low-level abortion in the dairy herd. Vertical transmission of infection was the predominant mode of infection and hence control efforts aimed at selectively culling seropositive animals from the herd were highly successful in reducing the level of infection.
确定犬新孢子虫对澳大利亚新南威尔士州一个奶牛场流产事件的影响，确定传播方式，并开发和试验感染的控制方案。
相隔12个月进行两次全群采血，计算了多种牛流产因素的血清学状态与流产事件之间的关联。构建了该牛群中犬新孢子虫血清阳性牛的系谱。从牛群中淘汰了一些犬新孢子虫血清阳性奶牛，血清阳性奶牛未保留雌性后代。
在2002年12月的第一次全群采血中，检测到犬新孢子虫感染的血清阳性率为10.2%。感染犬新孢子虫的奶牛流产的可能性是未感染奶牛的13倍。牛群中75%的血清阳性动物有亲缘关系，表明先天性感染/传播程度很高。只有15%的感染可能是出生后获得的。选择性淘汰血清阳性奶牛并避免用它们繁殖，减少了血清阳性动物的数量。在12个月后的第二次全群采血中，仅检测到一头新血清转化的奶牛。
血清流行病学方法能够确定犬新孢子虫感染与奶牛群低水平流产之间的高度关联。感染的垂直传播是主要的感染方式，因此旨在从牛群中选择性淘汰血清阳性动物的控制措施在降低感染水平方面非常成功。
