title: Increased susceptibility of Atlantic salmon Salmo salar to infections with Gyrodactylus derjavini induced by dexamethasone bath treatment.
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 microg dexamethasone l-1 water, respectively. In addition, one group (positive control) was treated intraperitoneally with 200 microg 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 microg l-1 water) and in the i.p. treated positive control group were significantly higher compared to the untreated control group.
authors.affiliation: Department of Veterinary Microbiology, Section of Fish Diseases, Royal Veterinary and Agricultural University, Stigbøjlen 4, DK-1870, Frederiksberg C, Denmark. cvn@kvl.dk
authors.forename: C V
authors.initials: CV
authors.lastname: Nielsen
authors.forename: K
authors.initials: K
authors.lastname: Buchmann
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology*; D004198:Disease Susceptibility; D006790:Host-Parasite Interactions; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007274:Injections, Intraperitoneal; D010274:Parasitology / Q000379:methods; D020317:Salmo salar / Q000276:immunology / Q000469:parasitology*; D014200:Trematoda / Q000502:physiology*; D014201:Trematode Infections / Q000276:immunology*
chemical_list: D007166:Immunosuppressive Agents; D003907:Dexamethasone