https://www.dnr.wa.gov/sites/default/files/publications/PRV%20whitepaper%20revised%20Sept%202017.pdf?3c0h5&b2f0s02j4iPrepared By
The Pacific Northwest Fish Health Protection Committee
By
T.R. Meyers
Alaska Department of Fish and Game
Juneau Fish Pathology Laboratory
Summary Conclusion Based on Available Data: The ubiquitous nature of piscine orthoreovirus (PRV), its apparent historic presence in wild Pacific salmonid stocks in the Pacific Northwest and the lack of clear association with disease in Pacific
salmonids suggest the virus poses a low risk to wild species of Pacific salmonids.
Why PRV in the PNW is of low risk regarding HSMI in wild Pacific Salmonids
1. The disease “heart and skeletal muscle inflammation” (HSMI) has not been reported in wild
salmon populations in Norway or elsewhere and appears to only be a threat to farmed fish
2. While PRV causes HSMI in farmed Norwegian Atlantic salmon, high levels of PRV genetic
material have been detected in asymptomatic wild and cultured salmonids with no evidence of
HSMI disease
3. Histopathological lesions of HSMI were recently described as statistically correlated with the
presence of PRV at one Atlantic salmon farm in British Columbia, Canada (BC) while other
studies have detected the presence of PRV genetic material in wild and cultured Chinook, coho
and pink salmon and steelhead trout from Washington State, BC and Alaska where years of
surveillance have reported no presence of HSMI
4. Molecular testing of archived fish tissues in BC has shown that PRV was present in
asymptomatic wild and farmed Pacific salmon since 1987 and may have been present as early as
1977 before Atlantic salmon were imported for aquaculture
5. HSMI has not been reported in Pacific salmon or steelhead in North America to date
6. Laboratory studies with Chinook and sockeye salmon have demonstrated that PRV is infectious
and will persist for quite some time but does not cause fish mortality, HSMI, or any other
apparent disease
7. Development of HSMI and HSMI-like diseases of farmed salmonids (Atlantic and coho
salmon; rainbow trout) infected by PRV may be a result of different viral strains, host specific
antiviral responses and environmental stressors that do not appear to be present or active for
indigenous salmon on the Pacific Coast
8. The presence of PRV genetic material in Pacific salmon tissues is not sufficient evidence
for HSMI disease
The PRV strain present in indigenous Pacific salmon in the PNW, historically and experimentally, appears to be relatively benign and unable to produce significant disease or HSMI in native salmonids.
Author
Topic: Get your facts straight? (Read 1343995 times)