Bisgaard M, Bojesen A M, Petersen M R, Christensen H
Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg C, Denmark.
Avian Dis. 2012 Sep;56(3):561-6. doi: 10.1637/10123-030712-Reg.1.
Infections of poultry due to Streptococcus equi subsp. zooepidemicus have been rare during the past decades and dissimilarities have been reported as to symptoms and lesions; likewise, the source of serious outbreaks has remained speculative. An outbreak affecting 11,000 free-range chickens at the age of 47 wk is reported. The outbreak manifested itself as acute at the onset and was followed by a chronic stage, resulting in some 80% mortality within 21 wk. Small-colony variants (SCVs) of S. equi subsp. zooepidemicus associated with the chronic phase are reported for the first time, and it is discussed whether SCVs might explain the change in lesions observed. Comparison of partial sequences of rpoB, multilocus sequence typing, and pulsed-field gel electrophoresis of isolates from chickens and horses kept at the farm showed the isolates to be identical and horses a likely source of infection. The present findings underline the importance of protecting free-range chickens from contact with other animals and birds known to host pathogens of importance to poultry.
在过去几十年中，马链球菌兽疫亚种引起的家禽感染较为罕见，且关于症状和病变的差异已有报道；同样，严重疫情的源头仍具推测性。本文报道了一起影响11000只47周龄散养鸡的疫情。疫情初期表现为急性，随后进入慢性阶段，在21周内导致约80%的死亡率。首次报道了与慢性阶段相关的马链球菌兽疫亚种小菌落变异株（SCVs），并讨论了SCVs是否可以解释所观察到的病变变化。对农场饲养的鸡和马的分离株进行rpoB部分序列比较、多位点序列分型和脉冲场凝胶电泳，结果显示分离株相同，马可能是感染源。目前的研究结果强调了保护散养鸡免受与已知携带对家禽重要病原体的其他动物和鸟类接触的重要性。
