Gill diseases cause serious losses in farming of Atlantic salmon and the number of agents involved increases. Salmon gill poxvirus ( SGPV ) and the gill disease in causes where SGPV apparently was the only disease‐causing agent were initially characterized. Recently, it was further shown that SGPV can be a common denominator in widely different multifactorial gill diseases. Here, we present the challenge of diagnosing gill dis...

In 2016, the Norwegian health monitoring programme for wild salmonids conducted a real‐time PCR ‐based screening for salmon gill poxvirus ( SGPV ) in anadromous Arctic char ( Salvelinus alpinus L.), anadromous and non‐anadromous Atlantic salmon ( Salmo salar L.) and trout ( Salmo trutta L.). SGPV was widely distributed in wild Atlantic salmon returning from marine migration. In addition, characteristic gill lesions, including...

Gill diseases cause considerable losses in Norwegian salmon farming. In 2015, we characterized salmon gill poxvirus ( SGPV ) and associated gill disease. Using newly developed diagnostic tools, we show here that SGPV infection is more widely distributed than previously assumed. We present seven cases of complex gill disease in Atlantic salmon farmed in seawater and freshwater from different parts of Norway. Apoptosis, the hall...

Elucidation of the role of infectious agents putatively involved in gill disease is commonly hampered by the lack of culture systems for these organisms. In this study, a farmed population of Atlantic salmon pre‐smolts, displaying proliferative gill disease with associated Candidatus Branchiomonas cysticola, Ca . Piscichlamydia salmonis and Atlantic salmon gill pox virus ( SGPV ) infections, was identified. A subpopulation of...

Serious infectious diseases, accompanied by macrophage‐dominated chronic inflammation, are common in farmed Atlantic cod. To increase knowledge relating to morphological aspects of such inflammatory responses, cod were challenged with Francisella noatunensis , an important bacterial pathogen of this fish species. Tissue and cell dynamics in the spleen were examined sequentially over 60 days. Small clusters of mainly macrophage...

Viral nervous necrosis (VNN) caused by betanodavirus affects many species of farmed marine fish, in particular juveniles. Apparently healthy, normally feeding, adult farmed Atlantic cod, Gadus morhua , were sampled in a farm 14 months after an outbreak of VNN with clinical signs. Following necropsy, brain and eye tissues were examined by histology, immunohistochemistry and polymerase chain reaction (PCR). Nodavirus‐provoked ce...