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ARS Home » Northeast Area » Leetown, West Virginia » Cool and Cold Water Aquaculture Research » Research » Publications at this Location » Publication #413399
Research Project: Improving Salmonid Health through Breeding, Vaccination and Microbiome Modulation

Location: Cool and Cold Water Aquaculture Research

Title: Exposure dosage and host genetics influence the shedding kinetics of Flavobacterium psychrophilum in rainbow trout

Author
item JONES, DARBI - Virginia Institute Of Marine Science
item EVERSON, JEREMY - Former ARS Employee
item Leeds, Timothy - Tim
item Wiens, Gregory - Greg
item WARGO, ANDREW - Virginia Institute Of Marine Science

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: A prevalent disease in rainbow trout aquaculture is bacterial cold water disease (BCWD). BCWD is caused by Flavobacterium psychrophilum. To date, there is little knowledge of the factors that influence F. psychrophilum transmission between fish. This paper measured the number of bacteria shed from BCWD resistant and susceptible trout strains infected with graded doses of the bacterium. As the infectious dose increased, the number of fish shedding and the amount of bacteria shed increased. In addition, we found that disease resistance (survival) was not correlated with transmission blocking, in that the majority of fish which shed bacteria, experienced no clinical disease. These data will help develop epidemiological models to improve disease management.

Technical Abstract: Flavobacterium psychrophilum, the causative agent of bacterial cold water disease (BCWD), is one of the leading pathogens in rainbow trout (Oncorhynchus mykiss) aquaculture. To date, there is little knowledge of the transmission kinetics of F. psychrophilum over the course of infection. In particular, how transmission is affected by host genotype and pathogen exposure dosage, are not well studied. In order to fill in these gaps, we exposed two divergently-selected lines of rainbow trout to a range of dosages of F. psychrophilum. We then measured mortality and bacterial shedding as a proxy for transmission, at multiple time points since initial infection. As dosage increased, the number of fish shedding and the amount of bacteria shed increased. In addition, we found that disease resistance (survival) was not correlated with transmission blocking, in that the majority of fish which shed bacteria, experienced no clinical disease. Results from this study could be used to develop epidemiological models and improve disease management, particularly in the context of aquaculture and selective breeding.