Systemic Flavobacterium psychrophilum infection in rainbow trout, Oncorhynchus mykiss (Walbaum), farmed in fresh and brackish water in Norway

Nilsen, Hanne; Olsen, Anne Berit; Vaagnes, Ø; Hellberg, Hege; Bottolfsen, Kirsten; Skjelstad, H. R.; Colquhoun, Duncan J.

doi:10.1111/j.1365-2761.2011.01249.x

Cited by 47 publications

(41 citation statements)

References 11 publications

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“…Degradation of elastin and a lowered sensitivity towards quinolones were constant traits among strains involved in the Norwegian RTFS/BCWD epizootic of 2008(Nilsen et al 2011. The lack of these traits in our current isolates from Atlantic salmon differentiates them from the rainbow trout epizootic strains isolated in Norway in the same year.…”

Section: Nilsen Et Al: Flavobacterium Psychrophilum In Atlantic Salmonmentioning

confidence: 63%

“…In Norwegian aquaculture -until the recent epizootic of RTFS/BCWD with its associated high losses in rainbow trout (Nilsen et al 2011) -isolations of Flavobacterium psychrophilum have been associated almost exclusively with occasional cases of fin rot and ulceration in Atlantic salmon Salmo salar (L.) and brown trout Salmo trutta (L.) (Johansen et al 2009). On a worldwide basis, although isolations of F. psychrophilum from Atlantic salmon are not uncommon, reports of systemic infections are scarce, lending support to observations that this species of fish is less susceptible to this disease (Holt et al 1993, Schmidtke & Carson 1995, Ekman et al 1999, Valdebenito & Avendaño-Herrera 2009.…”

Section: Introductionmentioning

confidence: 99%

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Flavobacterium psychrophilum associated with septicaemia and necrotic myositis in Atlantic salmon Salmo salar: a case report

Nilsen¹,

Johansen²,

Colquhoun³

et al. 2011

Dis. Aquat. Org.

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We describe the first case from Norway of increased mortality in Atlantic salmon Salmo salar (L.), with septicaemia and necrotic myositis, associated with infection by Flavobacterium psychrophilum. The outbreak occurred in smolt of 60 to 100 g in fresh water on a landbased farm in Western Norway during winter 2008−2009. The water temperature was < 5°C and the accumulated mortality was 7.0%. Necropsy of dead and moribund fish revealed a swollen dark spleen, pale liver, serohaemorrhagic ascites and haemorrhage in the abdominal fat and muscle. F. psychrophilum was isolated from the kidney and spleen of diseased fish. Muscle biopsy revealed the presence of long filamentous rods in necrotic areas of skeletal muscle. Immunohistochemistry was positive for F. psychrophilum. Identification of cultured isolates as F. psychrophilum was confirmed using phenotypic testing and sequencing of the 16S rRNA gene. Analysis by allele-specific polymerase chain reaction (allele-specific PCR) indicated that 2 different genotypes of the bacterium were present in the outbreak.KEY WORDS: Flavobacterium psychrophilum · Atlantic salmon · Necrotic myositis · Septicaemia · 16S rRNA allele Resale or republication not permitted without written consent of the publisherDis Aquat Org 97: 37-46, 2011 38 brown trout Salmo trutta (L.) (Johansen et al. 2009). On a worldwide basis, although isolations of F. psychrophilum from Atlantic salmon are not uncommon, reports of systemic infections are scarce, lending support to observations that this species of fish is less susceptible to this disease (Holt et al. 1993, Schmidtke & Carson 1995, Ekman et al. 1999, Valdebenito & Avendaño-Herrera 2009. To the best of our knowledge the present paper describes the first case in which F. psychrophilum has been associated with septicaemia and necrotic myositis in Atlantic salmon in Norway. MATERIALS AND METHODSCase history. The disease was first detected in late autumn 2008 in a group of 82 000 Atlantic salmon smolts of 60 to 100 g in a land-based unit in Western Norway. The water temperature was < 5°C. Owing to limited resources of fresh water, UV-treated sea water was used to buffer the fresh water, resulting in salinity of approximately 2 to 3 ‰.The fry were hatched in December 2007 at a freshwater site located in the same region; they were moved to the unit at the beginning of January 2008. Vaccination against infectious pancreatic necrosis was performed in April (AquaVac ® IPN Oral), and against furunculosis, vibriosis, coldwater vibriosis, Moritella viscosa infection and infectious pancreatic necrosis in August (Alphaject 6-2 ® , polyvalent i.p. vaccine). Despite completion of smoltification by October 2008, transfer of the smolts to sea water was delayed until the spring of 2009. Owing to this delay, the fish were revaccinated in November and December with a polyvalent i.p. vaccine against pancreatic disease (Norvax ® Compact PD) at 1.5 to 2°C. The mortality started to increase at the end of November, 2008, and remained elevated through December...

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Section: Nilsen Et Al: Flavobacterium Psychrophilum In Atlantic Salmonmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Flavobacterium psychrophilum associated with septicaemia and necrotic myositis in Atlantic salmon Salmo salar: a case report

Nilsen¹,

Johansen²,

Colquhoun³

et al. 2011

Dis. Aquat. Org.

Self Cite

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“…The predominance of ST2 in the Nordic countries, France (35), and Switzerland (42) and its association with severe BCWD outbreaks in rainbow trout make it a genotype of particular clinical significance. In Norway, where ST2 was responsible for mortalities of up to 90% during an epizootic in 2008 (26), its apparent host specificity was demonstrated during an outbreak in which only rainbow trout fry were affected on a site also producing Atlantic salmon juveniles. Since then, ST2 has also been responsible for recurrent outbreaks in brackish-water-farmed rainbow trout epidemiologically linked to the epizootics in 2008.…”

Section: Discussionmentioning

confidence: 99%

“…In the Nordic countries, where F. psychrophilum currently constitutes the main threat to rainbow trout production, BCWD was first reported in Denmark in 1985 (23,24) and in Sweden and Finland in 1986 and 1993, respectively (25). In Norway, F. psychrophilum was considered a minor problem in brown trout and salmon hatcheries until 2008, when an epidemic of systemic disease caused high mortalities in several rainbow trout farms (26). In Iceland, the number of outbreaks in rainbow trout is low but appears to be increasing (Gísli Jónsson, personal communication).…”

mentioning

confidence: 99%

Multilocus Sequence Typing Identifies Epidemic Clones of Flavobacterium psychrophilum in Nordic Countries

Nilsen

Sundell

Duchaud

et al. 2014

Appl Environ Microbiol

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f Flavobacterium psychrophilum is the causative agent of bacterial cold water disease (BCWD), which affects a variety of freshwater-reared salmonid species. A large-scale study was performed to investigate the genetic diversity of F. psychrophilum in the four Nordic countries: Denmark, Finland, Norway, and Sweden. Multilocus sequence typing of 560 geographically and temporally disparate F. psychrophilum isolates collected from various sources between 1983 and 2012 revealed 81 different sequence types (STs) belonging to 12 clonal complexes (CCs) and 30 singleton STs. The largest CC, CC-ST10, which represented almost exclusively isolates from rainbow trout and included the most predominant genotype, ST2, comprised 65% of all isolates examined. In Norway, with a shorter history (<10 years) of BCWD in rainbow trout, ST2 was the only isolated CC-ST10 genotype, suggesting a recent introduction of an epidemic clone. The study identified five additional CCs shared between countries and five country-specific CCs, some with apparent host specificity. Almost 80% of the singleton STs were isolated from non-rainbow trout species or the environment. The present study reveals a simultaneous presence of genetically distinct CCs in the Nordic countries and points out specific F. psychrophilum STs posing a threat to the salmonid production. The study provides a significant contribution toward mapping the genetic diversity of F. psychrophilum globally and support for the existence of an epidemic population structure where recombination is a significant driver in F. psychrophilum evolution. Evidence indicating dissemination of a putatively virulent clonal complex (CC-ST10) with commercial movement of fish or fish products is strengthened.

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“…Several clinical manifestations have been described among which the most significant are mortality in juvenile fish (RTFS) and in adult, septicemia preceded by extensive necrotic lesions (BCWD) [3]. Consequently, considerable economic losses to fish aquaculture producers can occur (up to 90% in rainbow trout farmed in Norway [4]) and the erosion of tissue leading to a commercial downgrade of adult fish (for a review of F. psychrophilum biology, clinical signs and BCWD prevention and treatment, [5]). The control of F. psychrophilum infections is difficult and no effective vaccine is available yet despite numerous studies focused on the capability of some F. psychrophilum proteins to induce protection in fish.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Glutaraldehyde, Chloramine-T, Bronopol, Incimaxx Aquatic® and Hydrogen Peroxide as Biocides against Flavobacterium psychrophilum for Sanitization of Rainbow Trout Eyed Eggs

Grasteau¹,

Daniel²,

Chesneau³

2015

J Aquac Res Development

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Systemic Flavobacterium psychrophilum infection in rainbow trout, Oncorhynchus mykiss (Walbaum), farmed in fresh and brackish water in Norway

Cited by 47 publications

References 11 publications

Flavobacterium psychrophilum associated with septicaemia and necrotic myositis in Atlantic salmon Salmo salar: a case report

Flavobacterium psychrophilum associated with septicaemia and necrotic myositis in Atlantic salmon Salmo salar: a case report

Multilocus Sequence Typing Identifies Epidemic Clones of Flavobacterium psychrophilum in Nordic Countries

Evaluation of Glutaraldehyde, Chloramine-T, Bronopol, Incimaxx Aquatic® and Hydrogen Peroxide as Biocides against Flavobacterium psychrophilum for Sanitization of Rainbow Trout Eyed Eggs

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