Downes J K, Yatabe T, Marcos-Lopez M, Rodger H D, MacCarthy E, O'Connor I, Collins E, Ruane N M
Fish Health Unit, Marine Institute, Oranmore, Galway, Ireland.
Marine and Freshwater Research Centre, Galway Mayo Institute of Technology, Galway, Ireland.
J Fish Dis. 2018 May 27. doi: 10.1111/jfd.12814.
Gill diseases are a complex and multifactorial challenge for marine farmed Atlantic salmon. Co-infections with putative pathogens are common on farms; however, there is a lack of knowledge in relation to the potential effect co-infections may have on pathology. The objective of this study was to determine the prevalence and potential effects of Neoparamoeba perurans, Desmozoon lepeophtherii, Candidatus Branchiomonas cysticola, Tenacibaculum maritimum and salmon gill poxvirus (SGPV) during a longitudinal study on a marine Atlantic salmon farm. Real-time PCR was used to determine the presence and sequential infection patterns of these pathogens on gill samples collected from stocking until harvest. A number of multilevel models were used to determine the effect of these putative pathogens on gill health (measured as gill histopathology score), while adjusting for the effect of water temperature and time since the last freshwater treatment. Results indicate that between 12 and 16 weeks post-seawater transfer (wpst), colonization of the gills by all pathogens had commenced and by week 16 of marine production each of the pathogens had been detected. D. lepeophtherii and Candidatus B. cysticola were by far the most prevalent of the potential pathogens detected during this study. Detections of T. maritimum were found to be significantly correlated with temperature showing distinct seasonality. Salmon gill poxvirus was found to be highly sporadic and detected in the first sampling point, suggesting a carryover from the freshwater stage of production. Finally, the model results indicated no clear effect between any of the pathogens. Additionally, the models showed that the only variable which had a consistent effect on the histology score was N. perurans.
鳃病对养殖的海洋大西洋鲑鱼来说是一个复杂且多因素的挑战。养殖场上与假定病原体的共感染很常见；然而，对于共感染可能对病理学产生的潜在影响，人们还缺乏了解。本研究的目的是在对一个海洋大西洋鲑鱼养殖场进行的纵向研究中，确定秘鲁新阿米巴、鳃虱变形虫、拟分支单胞菌、海生黄杆菌和鲑鱼鳃痘病毒（SGPV）的流行情况及潜在影响。使用实时PCR来确定这些病原体在从放养鱼苗到收获期间采集的鳃样本中的存在情况和相继感染模式。使用了多个多层次模型来确定这些假定病原体对鳃健康（以鳃组织病理学评分衡量）的影响，同时调整水温以及自上次淡水处理以来的时间的影响。结果表明，在海水转移后12至16周，所有病原体都已开始在鳃中定殖，到海水养殖第16周时，每种病原体都已被检测到。在本研究中检测到的潜在病原体中，鳃虱变形虫和拟分支单胞菌是迄今为止最普遍的。发现海生黄杆菌的检测与温度显著相关，呈现出明显的季节性。发现鲑鱼鳃痘病毒非常零星，在第一个采样点就被检测到，这表明它是从淡水养殖阶段遗留下来的。最后，模型结果表明任何一种病原体之间都没有明显影响。此外，模型显示，对组织学评分有一致影响的唯一变量是秘鲁新阿米巴。
