奶牛无乳链球菌性乳房炎的传播途径分析

Analysis of Transmission Routes of Bovine Mastitis Caused by Streptococcus agalactiae

奶牛乳房炎在给奶业造成巨大经济损失的同时,还严重影响原料奶的品质,关系着人类健康。无乳链球菌是导致奶牛乳房炎的主要病原菌之一,是典型的强传染性病原菌。2019年7月北方地区某奶牛场暴发无乳链球菌性乳房炎,乳房炎月度发病率约4%,无乳链球菌占比56%。本试验旨在通过对该牧场奶牛乳房内、外多个位点的无乳链球菌进行分离、鉴定,阐明无乳链球菌性乳房炎的传播途径。本试验共采集多个位点样品667份,共鉴定出无乳链球菌102株,其中奶样中的检出率为13.1%(26/198),粪便样品中的检出率为25.0%(5/20),垫料样品中的检出率为0(0/30),口腔样品中的检出率为26.2%(11/42),乳头末端皮肤样品中的检出率为2.6%(4/156),奶衬内壁拭子样品中的检出率为1.9%(2/104),正常奶厅挤奶员手臂拭子样品中的检出率为13.6%(3/22),洗手液、泡杯液样品中的检出率为0(0/30)。结果显示,该奶牛场主要存在的无乳链球菌传播途径有两条:挤奶厅接触传播(以挤奶工人的手臂传播为主)和粪—口—乳房传播。该奶牛场应着重针对这两条传播途径进行相应防控,形成综合性管控方案。本试验通过对无乳链球菌检出率进行综合分析,为该奶牛场制定乳房炎防控、治疗策略提供重要信息,具有重要的临床指导意义。

Bovine mastitis not only induces heavy economic losses to the dairy farms, but also affects the quality of milk, and thus poses potential risk to human health. Streptococcus agalactiae is one of the main pathogens causing bovine mastitis, and is noted for its high infectivity. Located in the northern region, the dairy farm in which this study was undertaken experienced an outbreak of S. agalactiae in July 2019, with monthly incidence of mastitis about 4%, and S. agalactiae accounting for 56% of the cases. Therefore, this study aimed to clarify the transmission routes of this S. agalactiae-related bovine mastitis outbreak through the isolation and identification of the culprit organisms inside and outside the udder. Of a total of 667 samples collected, 102 S. agalactiae isolates were obtained and identified. The detection rates of S. agalactiae in milk, feces, padding, oral swab, nipple skin’s end swab, liner, milker’s hand swab, and hand sanitizer and cup sanitizer samples were 13.1%(26/198), 25.0%(5/20), 0(0/30), 26.2%(11/42), 2.6%(4/156), 1.9%(2/104), 13.6%(3/22), and 0(0/30), respectively. The results demonstrated that two major transmission routes of S. agalactiae occurred in this dairy farm: Contacting in milking hall(mainly the arms of milkers) and fecal-oral-breast transmission route. Therefore, prevention strategies for this outbreak should concentrate on the monitoring these two transmission routes. Through the comprehensive analysis of the detection rates of S. agalactiae, this study provided important information for the dairy farm to treat, control and prevent mastitis.