Pseudomoniasis (P. anguilliseptica) in farmed fish

Leaflet No. 63
Pseudomoniasis (P. anguilliseptica)
in farmed fish
Pia Vennerström
International Council for the Exploration of the Sea
Conseil International pour l’Exploration de la Mer
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DK-1553 Copenhagen V
Telephone (+45) 33 38 67 00
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Recommended format for purposes of citation:
Vennerström, P. 2015. Pseudomoniasis (P. anguilliseptica) in farmed fish. ICES
Identification Leaflets for Diseases and Parasites of Fish and Shellfish. Leaflet No. 63.
4 pp.
Series Editor: Stephen Feist. Prepared under the auspices of the ICES Working Group
on Pathology and Diseases of Marine Organisms.
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ISBN 978-87-7482-160-1
ISSN 0109–2510
© 2015 International Council for the Exploration of the Sea
Leaflet No. 63
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Pseudomoniasis (P. anguilliseptica) in farmed fish
Pia Vennerström
Susceptible species
Infection caused by Pseudomonas anguilliseptica was originally reported in Japanese eel
(Anguilla japonica; Wakabayashi, et al., 1972). The disease agent seems to have a low
host specificity, having been reported in European eel (Anguilla Anguilla; Stewart, et
al., 1981), black sea bream (Achanthopagrus schlegeli; Nakajima, et al., 1983), ayu
(Plecoglossus altivelis; Nakai, et al., 1985), Atlantic salmon (Salmo salar), sea trout (Salmo
trutta), rainbow trout (Oncorynkhus mykiss) whitefish (Coregonus lavaretus; Wiklund,
and Bylund, 1990), Baltic herring (Clupea harengus membras; Lönnstrom, L. et al., 1994),
cod (Gadus morhua; Ferguson, et al., 2004) gilthead sea bream (Sparus aurata),
European sea bass (Dicentrarchus labrax) turbot (Scophthalmus maximus; Berthe, et al.,
1995) giant sea perch (Lates calcarifer), estuarine grouper (Epinephelus tauvina; Nash, et
al., 1987). It is mainly reported from marine and brackish water fish species.
Disease name
Pseudomoniasis, Sekiten-byo or red spot disease of Japanese eel.
Aetiological agent
Pseudomonads are common bacteria in the aquatic environment. Most are nonpathogenic bacteria or cause only secondary infections in connection to stress or
impaired disease resistance. Pseudomonas anguilliseptica is the most significant disease
agent of the pseduomonads for fish.
Geographical distribution
Infections caused by P. anguilliseptica are reported at least in Japan, Taiwan, Scotland,
Finland and France (Wakabayashi, et al., 1972; Stewart, et al., 1983; Wiklund, and
Bylund, 1990; Berthe, et al., 1995).
Associated environmental conditions
There are clear differences in seasonality between different isolates of P.
anguilliseptica. In Finland disease outbreaks in salmonids are mainly reported during
summer when water temperature is over 15°C (Wiklund, and Bylund, 1990). In Spain,
disease outbreaks are reported only during winter in temperatures below 12°C
(Domenech, et al., 1999).
Infections caused by P. anguilliseptica cause serious disease in eel farming, but are also
reported as a significant pathogen for other fish species in brackish and the marine
environment. In cod farming a low mortality rate of 2% occurs but mortalities of up
to 50% are reported from salmonids (Ferguson, et al., 2004; Wiklund, and Bylund,
Pseudomoniasis (P. anguilliseptica) in farmed fish
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Gross clinical signs
Infected fish show signs typical for a septic condition with petechial haemorrhages in
the skin of the ventral side of the body, mouth and the area around the vent. Affected
rainbow trout also show haemorrhages at the fin bases (Wiklund, and Bylund, 1990).
All species have petechial haemorrhages in the peritoneum, liver and adipose tissue.
Diseased cod get lethargic and gross lesions consist mainly of eye lesions and fin
Control measures and legislation
There are no commercial vaccines available for this disease agent. Treatment with
ampicillin or trimethoprim/sulfamethoxazole gives a good response. Infections by P.
anguilliseptica are not notifiable within the EU and are not listed by OIE.
Diagnostic methods
P. anguilliseptica is a long Gram negative rod that grows slowly on blood or TSA agar.
The optimal temperature for growing the bacteria is between 15–20°C. The semitransparent small (1 mm diameter) colonies appear after 3–4 days of incubation and
are easily overgrown by more rapidly dividing bacteria. The bacterium is inactive in
biochemical tests but serological and molecular based diagnostic methods are
available (Mar Blanco, et al., 2002; Romalde, et al., 2004). Histopathologically, a
granulomatous inflammation of connective tissues surrounding the skeleton/cartilage
of the head region is observed in cod (Ferguson, et al., 2004). In whitefish and
rainbow trout, oedematous lesions are reported in the liver tissue with cloudy
swelling of liver cells and focal necrotic areas. Oedematous changes are also seen in
kidney glomeruli and tubuli with detachment of tubular epithelium (Wiklund, and
Bylund, 1990).
Key references
Berthe, F. C. J., Michel, C., and Bernardet, J. F. 1995. Identification of Pseudomonas
anguilliseptica isolated from several fish species in France. Diseases of Aquatic
Organisms, 21(2): 151–155.
Domenech, A., Fernandez-Garayzabal, J. F., Garcia, J. A., Cutuli, M. T., Blanco, M.,
Gibello, A., Moreno, M. A., and Dominguez, L. 1999. Association of Pseudomonas
anguilliseptica infection with 'winter disease' in sea bream, Sparus aurata L. Journal
of Fish Diseases, 22(1): 69–71.
Ferguson, H. W., Collins, R. O., Moore, M., Coles, M., and MacPhee, D. D. 2004.
Pseudomonas anguilliseptica infection in farmed cod, Gadus morhua L. Journal of
Fish Diseases, 27(4): 249–253.
Lönnstrom, L., Wiklund, T., and Bylund, G. 1994. Pseudomonas anguilliseptica isolated
from Baltic herring Clupea harengus membras with eye lesions. Diseases of Aquatic
Organisms, 18: 143–147.
Mar Blanco, M., Gibello, A., Vela, A. I., Angel Moreno, M., Dominguez, L., and
Fernandez-Garayzabal, J. F. 2002. PCR detection and PFGE DNA macrorestriction analyses of clinical isolates of Pseudomonas anguilliseptica from winter
disease outbreaks in sea bream Sparus aurata. Diseases of Aquatic Organisms,
50(1): 19–27.
Nakai, T., Hanada, H., and Muroga, K. 1985. First records of Pseudomonas
anguilliseptica infection in cultured ayu, Plecoglossus altivelis. Fish Pathology, 20(4):
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Nakajima, K., Muroga, K., and Hancock, R. E. W. 1983. Comparison of fatty acid,
protein, and serological properties distinguishing outer membranes of
Pseudomonas anguilliseptica strains from those of fish pathogens and other
pseudomonads. International Journal of Systematic Bacteriology, 33(1): 1–8.
Nash, G., Anderson, I. G., Shariff, M., and Shamsudin, M. N. 1987. Bacteriosis
associated with epizootic in the giant sea perch, Lates calcarifer, and the estuarine
grouper, Epinephelus tauvina, cage cultured in Malaysia. Aquaculture, 67(12): 105–
Romalde, J. L., Lopez-Romalde, S., Ravelo, C., Magarinos, B., and Toranzo, A. E. 2004.
Development and validation of a PCR-based protocol for the detection of
Pseudomonas anguilliseptica. Fish Pathology, 39(1): 33–41.
Stewart, D. J., Woldemariam, K., Dear, G., and Mochaba, F. M. 1983. An outbreak of
'Sekiten-byo' among cultured European eels, Anguilla anguilla L., in Scotland.
Journal of Fish Diseases, 6(1): 75–76.
Wakabayashi, H., and Egusa, S. 1972. Characteristics of a Pseudomonas sp. from an
epizootic of pond-cultured eels (Anguilla japonica). Bulletin of the Japanese
Society of Scientific Fisheries, 38(6): 577–587.
Wiklund, T., and Bylund, G. 1990. Pseudomonas anguilliseptica as a pathogen of
salmonids in Finland. Diseases of Aquatic Organisms, 8: 13–19.
Figure 1. Rainbow trout infected by Pseudomonas anguilliseptica with oedema and petechial
haemorrhages in the skin of the vent.
Pseudomoniasis (P. anguilliseptica) in farmed fish
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A utho r C o nta ct I nfo r ma ti o n
Pia Vennerström
Finnish Food and Safety Authority
Mustialankatu 3
FI-00790 Helsinki
[email protected]