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

• Published in: Journal of Helminthology
• Main Authors: Nielsen, C.V., Buchmann, K.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2003
• Subjects: Animal Science and Zoology; General Medicine; Parasitology; Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1079/joh2002159; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022149X00702252

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.