Desmozoon lepeophtherii (microsporidian) infections and pancreas disease (PD) outbreaks in farmed Atlantic salmon ( Salmo salar L.)

Gunnarsson, Gunnar S.; Blindheim, Steffen H.; Karlsbakk, Egil; Plarre, Heidrun; Imsland, Albert K.; Handeland, Sigurd O.; Sveier, Harald; Nylund, Are

doi:10.1016/j.aquaculture.2016.09.035

Cited by 15 publications

(12 citation statements)

References 28 publications

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“…RNA was extracted from the sampled tissue as described by Gunnarson et al [ 25 ]. To increase the quality of the RNA, an additional washing step using 96% ethanol was performed.…”

Section: Methodsmentioning

confidence: 99%

Infection dynamics and tissue tropism of Parvicapsula pseudobranchicola (Myxozoa: Myxosporea) in farmed Atlantic salmon (Salmo salar)

Nylund

Hansen

Brevik³

et al. 2018

Parasites Vectors

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BackgroundThe myxosporean parasite Parvicapsula pseudobranchicola commonly infects farmed Atlantic salmon in northern Norway. Heavy infections are associated with pseudobranch lesions, runting and mortality in the salmon populations. The life-cycle of the parasite is unknown, preventing controlled challenge experiments. The infection dynamics, duration of sporogony, tissue tropism and ability to develop immunity to the parasite in farmed Atlantic salmon is poorly known. We conducted a field experiment, aiming at examining these aspects.MethodsInfections in a group of Atlantic salmon were followed from before sea-transfer to the end of the production (604 days). Samples from a range of tissues/sites were analysed using real-time RT-PCR and histology, including in situ hybridization.ResultsAll salmon in the studied population rapidly became infected with P. pseudobranchicola after sea-transfer medio August. Parasite densities in the pseudobranchs peaked in winter (November-January), and decreased markedly to March. Densities thereafter decreased further. Parasite densities in other tissues were low. Parasite stages were initially found to be intravascular in the pseudobranch, but occurred extravascular in the pseudobranch tissue at 3 months post-sea-transfer. Mature spores appeared in the pseudobranchs in the period with high parasite densities in the winter (late November-January), and were released (i.e. disappeared from the fish) in the period January-March. Clinical signs of parvicapsulosis (December-early February) were associated with high parasite densities and inflammation in the pseudobranchs. No evidence for reinfection was seen the second autumn in sea.ConclusionsThe main site of the parasite in Atlantic salmon is the pseudobranchs. Blood stages occur, but parasite proliferation is primarily associated with extravascular stages in the pseudobranchs. Disease and mortality (parvicapsulosis) coincide with the completion of sporogony. Atlantic salmon appears to develop immunity to P. pseudobranchicola. Further studies should focus on the unknown life-cycle of the parasite, and the pathophysiological effects of the pseudobranch infection that also could affect the eyes and vision.Electronic supplementary materialThe online version of this article (10.1186/s13071-017-2583-9) contains supplementary material, which is available to authorized users.

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“…RNA was extracted from the sampled tissue as described by Gunnarson et al [ 25 ]. To increase the quality of the RNA, an additional washing step using 96% ethanol was performed.…”

Section: Methodsmentioning

confidence: 99%

Infection dynamics and tissue tropism of Parvicapsula pseudobranchicola (Myxozoa: Myxosporea) in farmed Atlantic salmon (Salmo salar)

Nylund

Hansen

Brevik³

et al. 2018

Parasites Vectors

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“…Variation in co‐infections makes histopathological diagnosis of CGD highly complex (Gjessing et al 2019). The relationship between CGD and some of the associated pathogens has been described as dose‐dependent, but complex (Steinum et al 2010; Mitchell et al 2013; Gunnarsson et al 2017; Downes et al 2018a). For example, epitheliocysts were inconsistently observed in PGI‐positive cases (Mitchell et al 2013) and were found in lesser quantities in non‐PGI cases (Steinum et al 2010), and there were signs of a dose‐dependent relation between severity of PGI cases and epitheliocysts (Mitchell et al 2013).…”

Section: Complex Gill Disease and Related Syndromesmentioning

confidence: 99%

“…Desmozoon lepeophtherii occurs in apparently healthy fish, but is reportedly more abundant in diseased or compromised fish, such as fish diagnosed with PGI (Steinum et al 2010) and fish with a low condition factor (Gunnarsson et al 2017). Reports about associations between disease and D. lepeophtherii are scarce.…”

Section: Specific Types Of Marine Salmonid Gill Diseasementioning

confidence: 99%

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Epidemiology of marine gill diseases in Atlantic salmon (Salmo salar) aquaculture: a review

Boerlage

Ashby²,

Herrero³

et al. 2020

Reviews in Aquaculture

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Gill disease of farmed Atlantic salmon (Salmo salar) in the marine environment has emerged as a significant problem for the salmon aquaculture industry. Different types of marine salmon gill disease reported include amoebic gill disease (AGD), parasitic gill disease, viral gill disease, bacterial gill disease, zooplankton (cnidarian nematocyst)‐associated gill disease, harmful algal gill disease and chemical/toxin‐associated gill disease. The term ‘multifactorial gill disease’ is used when multiple distinguishable types of disease (as opposed to an obvious single primary type) are present. When gill disease is non‐specific, it is referred to as ‘complex gill disease’ (CGD) or ‘complex gill disorder’. These two terms are often used interchangeably and are overlapping. The significance of many infectious and non‐infectious agents that may be associated with CGD is often unclear. In this review, we summarise aspects of the different types of gill disease that are relevant to the epidemiology of gill disease and of CGD in particular. We also tabulate simultaneously occurring putative pathogens to explore the multifactorial nature of gill disease.

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“…Outbreaks of pancreas disease (PD) caused by salmonid alphavirus (SAV) affect farmed and wild populations of Atlantic salmon (Salmo salar) and other salmonids in many places around the world. Outbreaks of PD lasting 3-4 months regularly occur in Norway and are expensive, with direct costs of a single PD outbreak at a site stocked with 1 million salmon smolts estimated at Euro 7 million [1][2][3][4][5][6][7][8] . Monitoring and control is difficult as there are often no obvious external signs of infection (sub-clinical infections 9,10 ), and because an estimated one-third of SAV infected populations in Norway do not develop clinical PD 11 .…”

mentioning

confidence: 99%

Response of the Salmon Heart Transcriptome to Pancreas Disease: Differences Between High- and Low-Ranking Families for Resistance

Robinson

Krasnov

Burgerhout

et al. 2020

Sci Rep

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pancreas disease caused by salmonid alphaviruses leads to severe losses in Atlantic salmon aquaculture. The aim of our study was to gain a better understanding of the biological differences between salmon with high and low genomic breeding values (H-gEBV and L-gEBV respectively) for pancreas disease resistance. Fish from Hand L-gEBV families were challenged by intraperitoneal injection of salmonid alphavirus or co-habitation with infected fish. Mortality was higher with co-habitation than injection, and for L-than H-gEBV. Heart for RNA-seq and histopathology was collected before challenge and at four-and ten-weeks post-challenge. Heart damage was less severe in injection-challenged H-than L-gEBV fish at week 4. Viral load was lower in H-than L-gEBV salmon after co-habitant challenge. Gene expression differences between Hand L-gEBV manifested before challenge, peaked at week 4, and moderated by week 10. At week 4, H-gEBV salmon showed lower expression of innate antiviral defence genes, stimulation of Band T-cell immune function, and weaker stress responses. Retarded resolution of the disease explains the higher expression of immune genes in L-gEBV at week 10. Results suggest earlier mobilization of acquired immunity better protects H-gEBV salmon by accelerating clearance of the virus and resolution of the disease.

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Desmozoon lepeophtherii (microsporidian) infections and pancreas disease (PD) outbreaks in farmed Atlantic salmon ( Salmo salar L.)

Cited by 15 publications

References 28 publications

Infection dynamics and tissue tropism of Parvicapsula pseudobranchicola (Myxozoa: Myxosporea) in farmed Atlantic salmon (Salmo salar)

Infection dynamics and tissue tropism of Parvicapsula pseudobranchicola (Myxozoa: Myxosporea) in farmed Atlantic salmon (Salmo salar)

Epidemiology of marine gill diseases in Atlantic salmon (Salmo salar) aquaculture: a review

Response of the Salmon Heart Transcriptome to Pancreas Disease: Differences Between High- and Low-Ranking Families for Resistance

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