Wild Arctic char Salvelinus alpinus and trout Salmo trutta: hosts and reservoir of the salmonid pathogen Spironucleus salmonicida (Diplomonadida; Hexamitidae)

• Published in: Diseases of aquatic organisms Vol. 97; no. 1; pp. 57 - 63
• Main Authors: JØRGENSEN, Anders, TORP, Kari, BJØRLAND, Marie A, POPPE, Trygve T
• Format: Journal Article
• Language: English
• Published: Oldendorf Inter-Research 03.11.2011
• Subjects: Agnatha. Pisces; Animal aquaculture; Animal productions; Animals; Biological and medical sciences; Diplomonadida; Diplomonadida - genetics; Disease Reservoirs - veterinary; Fish Diseases - epidemiology; Fish Diseases - parasitology; Freshwater; Fundamental and applied biological sciences. Psychology; Gasterosteus aculeatus; Host-Parasite Interactions; Norway - epidemiology; Phylogeny; Protozoa; Protozoan Infections, Animal - epidemiology; Protozoan Infections, Animal - parasitology; Salmo salar; Salmo trutta; Salvelinus alpinus; Species Specificity; Spironucleus; Spironucleus barkhanus; Trout; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Norway; ANE, Norway; PN, Arctic; Salmonidae; Protozoa; Protozoal disease; Farming animal; Disease; Fish disease; Salmo salar; Ribosomal DNA; Farmed Atlantic salmon; Reservoir; Diplomonadida; Host; Spironucleosis; Parasitosis; Hatchery; Infection; Freshwater environment; Vertebrata; Salmo trutta; Excavata; Co-infection; Pisces; SSU rDNA; Salvelinus alpinus
• DOI: 10.3354/dao02404
• ISSN: 0177-5103

Spironucleus salmonicida is a diplomonad flagellate known to cause systemic infections in farmed salmonids. In northern Norway, outbreaks of spironucleosis in farmed Atlantic salmon Salmo salar have been a recurring problem. Common to all these outbreaks was the origin of smolts: all came from the same farm. In the present study, wild Arctic char Salvelinus alpinus and brown trout Salmo trutta were sampled from the lakes used as a water source for the smolt supplier. In addition, smolt and three-spined sticklebacks Gasterosteus aculeatus were sampled from the smolt farm. Bile and intestinal contents from the sampled fish were examined by light microscopy and PCR. Spironucleus salmonicida was identified in both wild Arctic char and brown trout from the lakes used as water sources by the smolt farm, suggesting that the farmed fish were exposed to this pathogen before transfer to the sea. Spironucleus barkhanus and Spironucleus salmonis were also identified in the sampled fish. The present study also demonstrated that infections with multiple Spironucleus species are present in wild salmonids. No indications of disease related to diplomonad infections were observed in the wild fish, suggesting that wild salmonids are reservoir hosts of Spironucleus salmonicida.