Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, Institute for Fish and Wildlife Health, University of Bern, Bern, Switzerland.
Fishdoc GmbH, Rain, Switzerland.
J Fish Dis. 2023 Sep;46(9):987-999. doi: 10.1111/jfd.13819. Epub 2023 Jun 9.
Nodular gill disease (NGD) is an infectious condition characterized by proliferative gill lesions leading to respiratory problems, oxygen deficiency and mortality in fish. Globally, NGD primarily impacts freshwater salmonids in intensive aquaculture systems. In recent years, numerous outbreaks of severe gill disease have affected more than half of the larger rainbow trout (Oncorhynchus mykiss) farms in Switzerland, mainly during spring and early summer. Mortality has reached up to 50% in cases where no treatment was administered. Freshwater amoeba are the presumed aetiologic agent of NGD. The gross gill score (GS) categorising severity of gill pathology is a valuable first-line diagnostic tool aiding fish farmers in identifying and quantifying amoebic gill disease (AGD) in farmed marine salmonids. In this study, the GS was adapted to the NGD outbreak in farmed trout in Switzerland. In addition to scoring disease severity, gill swabs from NGD-affected rainbow trout were sampled and amoeba were cultured from these swabs. Morphologic and molecular methods identified six amoeba strains: Cochliopodium sp., Naegleria sp., Vannella sp., Ripella sp., Saccamoeba sp. and Mycamoeba sp. However, the importance of the different amoeba species for the onset and progression of NGD still has to be evaluated. This paper presents the first description of NGD with associated amoeba infection in farmed rainbow trout in Switzerland.
结节性鳃病（NGD）是一种传染性疾病，其特征是增生性鳃损伤导致鱼类呼吸问题、缺氧和死亡。在全球范围内，NGD 主要影响集约化水产养殖系统中的淡水鲑鱼。近年来，瑞士有半数以上的大型虹鳟养殖场（Oncorhynchus mykiss）爆发了严重的鳃病，主要发生在春季和初夏。在未进行治疗的情况下，死亡率高达 50%。淡水阿米巴被认为是 NGD 的病原体。用于评估鳃病严重程度的总鳃评分（GS）是一种有价值的一线诊断工具，可帮助养鱼户识别和量化养殖鲑鱼的阿米巴鳃病（AGD）。在这项研究中，GS 被应用于瑞士养殖鳟鱼的 NGD 爆发。除了对疾病严重程度进行评分外，还从受 NGD 影响的虹鳟鱼的鳃拭子中取样，并从这些拭子中培养阿米巴。形态学和分子方法鉴定了六种阿米巴菌株：Cochliopodium sp.、Naegleria sp.、Vannella sp.、Ripella sp.、Saccamoeba sp. 和 Mycamoeba sp. 然而，不同阿米巴物种对 NGD 的发病和进展的重要性仍有待评估。本文首次描述了瑞士养殖虹鳟鱼中与 NGD 相关的阿米巴感染。
