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Increased susceptibility of Atlantic salmon Salmo salar to infections with Gyrodactylus derjavini induced by dexamethasone bath treatment

Published online by Cambridge University Press:  12 April 2024

C.V. Nielsen*
Affiliation:
Department of Veterinary Microbiology, Section of Fish Diseases, Royal Veterinary and Agricultural University, Stigbøjlen 4, DK-1870, Frederiksberg C, Denmark
K. Buchmann
Affiliation:
Department of Veterinary Microbiology, Section of Fish Diseases, Royal Veterinary and Agricultural University, Stigbøjlen 4, DK-1870, Frederiksberg C, Denmark
*
*Author for correspondence Fax: +45 35 28 27 11 Email: cvn@kvl.dk

Abstract

Dexamethasone, a known immunosuppressant, was administered by bath or injection to Atlantic salmon Salmo salar (Conon stock) to study if this treatment could affect the susceptibility of fish to infections with a Danish strain of Gyrodactylus derjavini (Monogenea). Three groups of S. salar (Conon stock) were immersion treated either with 10, 60 or 240 μg dexamethasone l-1 water, respectively. In addition, one group (positive control) was treated intraperitoneally with 200 μg dexamethasone per fish and one negative control group was kept untreated. A single G. derjavini parasite was placed on the anal fin of each fish and the infection was subsequently monitored weekly for 6 weeks. An increase in parasite populations on the salmon was positively correlated with the amount of immunosuppressant used. Infection levels in the group immersion treated with dexamethasone (240 μg l-1 water) and in the i.p. treated positive control group were significantly higher compared to the untreated control group.

Type
Review Article
Copyright
Copyright © Cambridge University Press 2003

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