Abortions in dairy animals can be caused by several infectious agents. Identification of the actual causal agent(s) is important for formulating suitable control strategies. A 3-year (2016–2018) longitudinal study was conducted in a dairy farm following an abortion storm in the mid- to late gestations. The investigation focused on the seven major infectious abortifacient in cattle, viz. bovine alphaherpesvirus-1 (BoHV-1), bovine viral diarrhoea virus (BVDV), Neospora caninum , Brucella abortus , Coxiella burnetii , Leptospira Hardjo, and Listeria monocytogenes . High seroprevalence was observed for BVDV (79.4%), Leptospira (70.5%), BoHV-1 (53.5%), and Brucella (45.0%) at the beginning of the investigation (August 2016). The incidence proportion increased for BVDV, Leptospira , and Brucella in the following years of the investigation. A strong association of Brucella seropositivity with history of abortion (OR = 3.27) was recorded. Incidence of BoHV-1 reduced during the period of study coincident with systematic IBR inactivated marker vaccination of the herd. Sixty-four abortion cases were investigated for the identification of causative agent(s) by microbial culture, serological (ELISA), and molecular detection (PCR/ real-time PCR). Antibodies to BVDV, Brucella , BoHV-1, Leptospira, Neospora, and Coxiella were detected in 63, 61, 56, 35, 5, and 6 aborting cattle, respectively. Real-time PCR/PCR of clinical specimens detected DNA of Brucella, BoHV-1, Coxiella, Leptospira , and Listeria in 34, 13, 12, 9, and 4 abortion cases, respectively. BVDV and Neospora were not detected in any specimen samples. Brucella abortus isolated from the farm was determined as ST1 by multi-locus sequence typing (MLST). DNA of multiple agents were detected in 21 of the 64 cases (43.75%). Overall, the data suggests, Brucella was the major causative agent, although multiple causative agents circulated in the farm.

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传染性牛流产：来自有组织的奶牛群的观察

奶牛流产可能是由几种传染性病原体引起的。确定实际致病因子对于制定合适的控制策略很重要。在妊娠中期至晚期发生流产风暴后，在一家奶牛场进行了一项为期 3 年（2016-2018 年）的纵向研究。调查的重点是牛的七种主要传染性流产剂，即。牛 alphaherpesvirus-1 (BoHV-1)、牛病毒性腹泻病毒 (BVDV)、犬新孢子虫、流产布鲁氏菌、伯内氏柯克氏杆菌、哈氏钩端螺旋体和单核细胞增生李斯特菌。在调查开始时（2016 年 8 月）观察到 BVDV（79.4%）、钩端螺旋体（70.5%）、BoHV-1（53.5%）和布鲁氏菌（45.0%）的高血清阳性率。在随后几年的调查中，BVDV、钩端螺旋体和布鲁氏菌的发病率有所增加。布鲁氏菌血清阳性与流产史密切相关（OR = 3.27）。在研究期间，BoHV-1 的发病率降低，这与猪群的系统性 IBR 灭活标志物疫苗接种一致。通过微生物培养、血清学 (ELISA) 和分子检测 (PCR/实时 PCR) 对 64 例流产病例进行了调查，以确定病原体。分别在 63、61、56、35、5 和 6 头流产牛中检测到 BVDV、布鲁氏菌、BoHV-1、钩端螺旋体、新孢子菌和柯氏杆菌抗体。临床标本的实时 PCR/PCR 分别在 34、13、12、9 和 4 例流产病例中检测到布鲁氏菌、BoHV-1、柯克希氏菌、钩端螺旋体和李斯特菌的 DNA。在任何标本样本中均未检测到 BVDV 和新孢子虫。从农场分离的流产布鲁氏菌通过多位点序列分型 (MLST) 确定为 ST1。64例中有21例（43.75%）检测到多种药物的DNA。总体而言，数据表明，布鲁氏菌是主要的病原体，尽管农场中传播了多种病原体。