Amoeba species colonizing the gills of rainbow trout (Oncorhynchus mykiss) in Swiss aquaculture.

Vannetti, Stefania M; Wynne, James W; English, Chloe; Huynh, Christine; Knüsel, Ralph; de Sales-Ribeiro, Carolina; Widmer, Maro; Delalay, Gary; Schmidt-Posthaus, Heike (2023). Amoeba species colonizing the gills of rainbow trout (Oncorhynchus mykiss) in Swiss aquaculture. Journal of fish diseases, 46(9), pp. 987-999. Wiley 10.1111/jfd.13819

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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.

Item Type:

Journal Article (Original Article)


05 Veterinary Medicine > Department of Infectious Diseases and Pathobiology (DIP)
05 Veterinary Medicine > Department of Infectious Diseases and Pathobiology (DIP) > Center for Fish and Wildlife Health (FIWI)
08 Faculty of Science > Department of Biology > Bioinformatics and Computational Biology

UniBE Contributor:

Vannetti, Stefania Michaela, de Sales Ribeiro, Maria Carolina, Widmer, Maro Linus, Delalay, Gary, Schmidt-Posthaus, Heike


600 Technology > 630 Agriculture








Pubmed Import

Date Deposited:

12 Jun 2023 09:56

Last Modified:

10 Aug 2023 00:16

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Uncontrolled Keywords:

Oncorhynchus mykiss Switzerland amoeba next-generation sequencing nodular gill disease rainbow trout




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