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Complex Gill Disease: an Emerging Syndrome in Farmed Atlantic Salmon (Salmo salar L.). J Comp Pathol 2018; 163:23-28. [PMID: 30213370 DOI: 10.1016/j.jcpa.2018.07.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 07/05/2018] [Accepted: 07/18/2018] [Indexed: 11/19/2022]
Abstract
Gill disorders have become a significant problem during the marine phase of farming Atlantic salmon (Salmo salar L.). The term complex gill disease (CGD) includes a wide range of clinical gill disease presentations generally occurring from the end of summer to early winter on marine Atlantic salmon farms. The gross and histological lesions observed are the resultant culmination of exposure to a mixture of environmental insults, pathogenic organisms and farm management practices. None of the three principal agents purportedly associated with CGD (Desmozoon lepeophtherii, salmon gill poxvirus or Candidatus Branchiomonas cysticola) have been cultured successfully in-vitro, so individual in-vivo challenge studies to identify their pathogenesis have not been possible. Studies of cohabitation of single pathogen-infected fish with naïve fish, and epidemiological investigations are required urgently to elucidate the roles of these pathogens and other factors in CGD.
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Investigation of co-infections with pathogens associated with gill disease in Atlantic salmon during an amoebic gill disease outbreak. JOURNAL OF FISH DISEASES 2018; 41:1217-1227. [PMID: 29806080 DOI: 10.1111/jfd.12814] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 03/13/2018] [Accepted: 03/14/2018] [Indexed: 06/08/2023]
Abstract
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.
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Oxidative stress is associated with late-stage amoebic gill disease in farmed Atlantic salmon (Salmo salar L.). JOURNAL OF FISH DISEASES 2018; 41:383-387. [PMID: 28836667 DOI: 10.1111/jfd.12699] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Revised: 07/10/2017] [Accepted: 07/12/2017] [Indexed: 06/07/2023]
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Piscine myocarditis virus detected in corkwing wrasse (Symphodus melops) and ballan wrasse (Labrus bergylta). JOURNAL OF FISH DISEASES 2018; 41:147-152. [PMID: 28791724 DOI: 10.1111/jfd.12661] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/03/2017] [Accepted: 05/04/2017] [Indexed: 06/07/2023]
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Piscirickettsia salmonis infection in cultured lumpfish (Cyclopterus lumpus L.). JOURNAL OF FISH DISEASES 2017; 40:1625-1634. [PMID: 28429818 DOI: 10.1111/jfd.12630] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/07/2017] [Accepted: 02/09/2017] [Indexed: 06/07/2023]
Abstract
A Piscirickettsia salmonis infection was diagnosed in lumpfish (Cyclopterus lumpus L.) juveniles held in a marine research facility on the west coast of Ireland. The main clinical signs and pathology included marked ascites, severe multifocal liver necrosis and severe diffuse inflammation and necrosis of the exocrine pancreas and peri-pancreatic adipose tissue. Numerous Piscirickettsia-like organisms were observed by histopathology in the affected organs, and the bacterial species was characterized by molecular analysis. Sequencing of the partial 16S rDNA gene and internal transcribed spacer region showed the lumpfish sequences to be closely related to previously identified Atlantic salmon (Salmo salar L.) sequences from Ireland. To the authors' knowledge, this is the first detection of P. salmonis in lumpfish worldwide. The infection is considered potentially significant in terms of lumpfish health and biosecurity.
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First record of Tetramicra brevifilum in lumpfish (Cyclopterus lumpus, L.). JOURNAL OF FISH DISEASES 2017; 40:757-771. [PMID: 27716959 DOI: 10.1111/jfd.12554] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Revised: 07/26/2016] [Accepted: 07/27/2016] [Indexed: 06/06/2023]
Abstract
A microsporidian species with 98.3-98.4% nucleotide identity to Tetramicra brevifilum (Journal of Fish Diseases, 3, 1980, 495) was diagnosed in lumpfish (Cyclopterus lumpus, L.) broodstock held at a breeding and rearing facility in western Ireland. The fish were wild-caught from the west coast of Ireland, and the first case was diagnosed one year after capture. Clinical signs included severe bloating, lethargy, exophthalmos, anorexia, white patches on the cornea and externally visible parasitic cysts on skin and fins. Necropsy revealed severe ascites, white nodules and vacuoles in all the internal organs and partial liquefaction of the skeletal muscle. On histological examination, microsporidian xenomas were observed in all internal organs, the skin, skeletal muscle, gills and the eyes. The microsporidian species was identified by molecular analysis and transmission electron microscopy. This is the first record of T. brevifilum infecting lumpfish, and the disease is considered to be of potential significance to the rising aquaculture industry of this species.
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The epidemiology of pancreas disease in salmonid aquaculture: a summary of the current state of knowledge. JOURNAL OF FISH DISEASES 2017; 40:141-155. [PMID: 27136332 DOI: 10.1111/jfd.12478] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 02/12/2016] [Accepted: 02/18/2016] [Indexed: 05/13/2023]
Abstract
Pancreas disease (PD) is a viral disease caused by Salmonid alphavirus (SAV) that affects farmed Atlantic salmon (Salmo salar L.) and rainbow trout (Oncorhynchus mykiss (Walbaum)) in the seawater phase. Since its first description in Scotland in 1976, a large number of studies have been conducted relating to the disease itself and to factors contributing to agent spread and disease occurrence. This paper summarizes the currently available, scientific information on the epidemiology of PD and its associated mitigation and control measures. Available literature shows infected farmed salmonids to be the main reservoir of SAV. Transmission between seawater sites occurs mainly passively by water currents or actively through human activity coupled with inadequate biosecurity measures. All available information suggests that the current fallowing procedures are adequate to prevent agent survival within the environment through the fallowing period and thus that a repeated disease outbreak at the same site is due to a new agent introduction. There has been no scientific evaluation of currently used on-site biosecurity measures, and there is limited information on the impact of available mitigation measures and control strategies.
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Pathology and mortality associated with the mauve stinger jellyfish Pelagia noctiluca in farmed Atlantic salmon Salmo salar L. JOURNAL OF FISH DISEASES 2016; 39:111-115. [PMID: 24909954 DOI: 10.1111/jfd.12267] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 04/11/2014] [Accepted: 05/07/2014] [Indexed: 06/03/2023]
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An outbreak of francisellosis in wild-caught Celtic Sea Atlantic cod, Gadus morhua L., juveniles reared in captivity. JOURNAL OF FISH DISEASES 2015; 38:97-102. [PMID: 24261672 DOI: 10.1111/jfd.12210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 10/15/2013] [Accepted: 10/16/2013] [Indexed: 06/02/2023]
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Genetic diversity and associated pathology of rhabdovirus infections in farmed and wild perch Perca fluviatilis in Ireland. DISEASES OF AQUATIC ORGANISMS 2014; 112:121-130. [PMID: 25449323 DOI: 10.3354/dao02801] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Rhabdovirus infections are an emerging problem for both wild and farmed freshwater fish in Northern Europe. In October 2005, a clinical outbreak with an approximate mortality rate of 40% occurred in a single batch of juvenile perch on a farm in the Republic of Ireland. Clinical signs developed slowly and were consistent with a perch rhabdovirus infection: signs included haemorrhages at the base of the fins and apparent impairment of the central nervous system (manifested as loss of equilibrium and erratic swimming behaviour). Studies suggest that the infected fish originated from a hatchery within the country which relied on wild fish broodstock to supplement the production of perch juveniles. A related rhabdovirus was subsequently isolated from this hatchery. Virus isolation studies have shown that rhabdoviruses were often isolated from wild fish in the vicinity of the hatchery between 1993 and 2005. All isolates were analysed using a generic primer set specific for the L gene of fish vesiculotype viruses. Phylogenetic analysis revealed that all isolates recovered from perch clustered together with the European lake trout rhabdovirus (903/87) of the genus Perhabdovirus. In addition to this, anguillid rhabdovirus was isolated from eel, and the partial L-gene sequence of a previously reported isolate from tench clustered with the pike fry rhabdoviruses, in the genus Sprivivirus.
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Clinical cardiomyopathy syndrome in Atlantic salmon, Salmo salar L. JOURNAL OF FISH DISEASES 2014; 37:935-939. [PMID: 24117690 DOI: 10.1111/jfd.12186] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 08/22/2013] [Accepted: 08/25/2013] [Indexed: 06/02/2023]
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Gill pathology in farmed salmon associated with the jellyfish
Aurelia aurita. VETERINARY RECORD CASE REPORTS 2013. [DOI: 10.1136/vetreccr.100045rep] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Development of a quantitative real-time PCR for the detection of Tenacibaculum maritimum and its application to field samples. JOURNAL OF FISH DISEASES 2012; 35:579-590. [PMID: 22724390 DOI: 10.1111/j.1365-2761.2012.01377.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The development and the application of a quantitative real-time PCR for the detection of Tenacibaculum maritimum are described. A set of primers and probe was designed to amplify a 155-bp fragment specific to the T. maritimum 16S rRNA gene. The test was shown to be very sensitive, able to detect as little as 4.8 DNA copies number μL(-1) . In addition, the assay was found to have a high degree of repeatability and reproducibility, with a linear dynamic range (R(2) = 0.999) extending over 6 log(10) dilutions and a high efficiency (100%). The assay was applied to DNA samples extracted from 48 formalin-fixed paraffin-embedded (FFPE) Atlantic salmon, Salmo salar, gill tissues showing varying degrees of gill pathology (scored 0-3) and from 26 jellyfish samples belonging to the species Phialella quadrata and Muggiaea atlantica. For each sample, the bacterial load was normalised against the level of the salmonid elongation factor alpha 1 (ELF) detected by a second real-time PCR using previously published primers and probe. Tenacibaculum maritimum DNA was detected in 89% of the blocks with no signs of gill disease as well as in 95% of the blocks with mild-to-severe gill pathology. Association between bacterial load and gill pathology severity was investigated. T. maritimum DNA was detected at low level in four of the 26 jellyfish tested.
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Abstract
Infectious gill diseases of marine salmonid fish present a significant challenge in salmon-farming regions. Infectious syndromes or disease conditions affecting marine-farmed salmonids include amoebic gill disease (AGD), proliferative gill inflammation (PGI) and tenacibaculosis. Pathogens involved include parasites, such as Neoparamoeba perurans, bacteria, such as Piscichlamydia salmonis and Tenacibaculum maritimum, and viruses, such as the Atlantic salmon paramyxovirus (ASPV). The present level of understanding of these is reviewed with regard to risk factors, potential impacting factors, methods of best practice to mitigate infectious gill disease, as well as knowledge gaps and avenues for future research.
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Erythrocytic inclusion body syndrome virus in wild Atlantic salmon, Salmo salar L. JOURNAL OF FISH DISEASES 2007; 30:411-8. [PMID: 17584438 DOI: 10.1111/j.1365-2761.2007.00831.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
An investigation was undertaken to establish aspects of the epizootiology of erythrocytic inclusion bodies in wild Atlantic salmon, Salmo salar L., in Scotland. From 1992 to 1995, adult and juvenile salmon, from Scottish rivers, were screened for the presence of erythrocytic inclusion bodies and haematological parameters measured. The nature of the inclusion bodies was assessed through transmission electron microscopy, negative-staining and blood smear-staining techniques and was demonstrated to be viral in origin with characteristics similar to a member of the family Togaviridae. Specifically, these were a viral genome of single-stranded RNA, spherical virion morphology with an icosahedral core, average size of 70 nm and a buoyant density of 1.15-1.20 g cm(-3). The cytoplasmic inclusions were either large, single inclusions (1-2 microm) or smaller multiple inclusions (0.5-1 microm). A total of 4.2% (n=48) and 27.7% (n=213) of the parr and adult salmon, respectively, were positive for the presence of the inclusions. The intensity of the inclusions, when present, varied from light in parr to moderate and heavy in adults, when graded according to the number of inclusions per field of view. Neither haematological variations nor clinical disease was associated with the presence or absence of viral inclusions.
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Abstract
Farmed pre-smolt stage Atlantic salmon developed an acute, severe haemorrhagic anaemia, termed haemorrhagic smolt syndrome. The fish were in good condition, but lethargic, and had widespread visceral and muscle petechiation and ecchymoses. The mean (sd) haematocrit of affected fish was 1.4(0.9) per cent and histopathology revealed widespread haemorrhage in all organs, associated with endothelial tissue. No infectious agent was isolated and the condition could not be transmitted experimentally. The clinical evidence indicates that the condition is non-infectious, but its aetiology could not be fully established.
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Clinical infectious pancreatic necrosis virus infection in farmed halibut in the United Kingdom. Vet Rec 1997; 140:401-2. [PMID: 9141224 DOI: 10.1136/vr.140.15.401] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Cell culture isolation of piscine neuropathy nodavirus from juvenile sea bass, Dicentrarchus labrax. J Gen Virol 1996; 77 ( Pt 9):2067-71. [PMID: 8811004 DOI: 10.1099/0022-1317-77-9-2067] [Citation(s) in RCA: 189] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
A virus causing a vacuolating encephalopathy and retinopathy in juvenile sea bass, Dicentrarchus labrax, was isolated from brain tissue in a fish cell line (SSN-1) derived from striped snakehead, Channa striatus. The isometric, non-enveloped, 30 nm diameter virus particles were resistant to pH 2-9 and heating at 56 degrees C for 30 min. Infectious particles had a buoyant density of approximately 1.31 g/cm3 in CsCl. Two structural polypeptides of molecular mass 40 and 42 kDa were identified and the ssRNA consisted of two fragments of molecular mass 1.10 and 0.51 x 10(6) Da. From these characteristics the virus was identified as a nodavirus. Due to the broad range of susceptible fish hosts and the consistent neuropathology of the disease condition, the generic term piscine neuropathy nodavirus (PNN) is proposed for this infectious agent.
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Nervous mortality syndrome in farmed Atlantic salmon. Vet Rec 1995; 137:616-7. [PMID: 8746852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Apparent lack of response of salmon affected by pancreas disease to pancreatic enzyme replacement therapy. Vet Rec 1995; 136:489-91. [PMID: 7544043 DOI: 10.1136/vr.136.19.489] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A trial was conducted to establish whether there would be any benefit in feeding mammalian pancreatic enzymes to farmed salmon clinically affected by pancreas disease. Pancreatic enzymes were incorporated at a rate of 4 kg/tonne of feed and fed at 0.6 to 0.9 per cent bodyweight/day for 41 days to one cage of salmon. The weights, lengths and condition factors were established for the fish before and after the feeding trial and compared with those for an adjacent cage of untreated fish. Histopathology and blood amylase and lipase activities were monitored weekly. No significant increases in weight or condition factor, and no reduction in mortalities were recorded. Histopathology confirmed the presence of pancreas disease throughout the trial and there were concurrent skeletal and cardiac myopathies. Blood amylase activities showed no significant change and were considered to be within normal ranges; blood lipase activity remained undetectable.
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Abstract
The factors involved in the development of 'summer lesion syndrome' were studied on 13 salmon farms based in the coastal waters of the west of Ireland. The primary causal factor in the development of the syndrome appeared to be overexposure to solar ultraviolet radiation. The pathology of the condition is described, the predisposing and reinforcing factors are considered and a hypothesis for the cause of the syndrome is proposed.
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