title: Effects of temperature on Renibacterium salmoninarum infection and transmission potential in Chinook salmon, Oncorhynchus tshawytscha (Walbaum).
abstract: Renibacterium salmoninarum is a significant pathogen of salmonids and the causative agent of bacterial kidney disease (BKD). Water temperature affects the replication rate of pathogens and the function of the fish immune system to influence the progression of disease. In addition, rapid shifts in temperature may serve as stressors that reduce host resistance. This study evaluated the effect of shifts in water temperature on established R. salmoninarum infections. We challenged Chinook salmon with R. salmoninarum at 12 °C for 2 weeks and then divided the fish into three temperature groups (8, 12 and 15 °C). Fish in the 8 °C group had significantly higher R. salmoninarum-specific mortality, kidney R. salmoninarum loads and bacterial shedding rates relative to the fish held at 12 or 15 °C. There was a trend towards suppressed bacterial load and shedding in the 15 °C group, but the results were not significant. Bacterial load was a significant predictor of shedding for the 8 and 12 °C groups but not for the 15 °C group. Overall, our results showed little effect of temperature stress on the progress of infection, but do support the conclusion that cooler water temperatures contribute to infection progression and increased transmission potential in Chinook salmon infected with R. salmoninarum.
authors.affiliation: U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: Purcell
authors.affiliation: U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA.
authors.forename: C L
authors.initials: CL
authors.lastname: McKibben
authors.affiliation: U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA.
authors.forename: S
authors.initials: S
authors.lastname: Pearman-Gillman
authors.affiliation: U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA.
authors.forename: D G
authors.initials: DG
authors.lastname: Elliott
authors.affiliation: U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Winton
mesh_terms: D000193:Actinomycetales Infections / Q000382:microbiology / Q000635:transmission / Q000662:veterinary*; D000818:Animals; D058491:Bacterial Load; D057138:Bacterial Shedding; D018450:Disease Progression; D005393:Fish Diseases / Q000382:microbiology / Q000635:transmission*; D007674:Kidney Diseases / Q000382:microbiology / Q000662:veterinary*; D008835:Micrococcaceae / Q000502:physiology*; D012474:Salmon; D013312:Stress, Physiological; D013696:Temperature; D014922:Wisconsin
keywords: Chinook salmon; Lake Michigan; bacterial load; shedding; temperature