Q&A on ISA, what we know about ISA in British Columbia
BCSFA, December 9, 2011
As a result of recent news stories, the BCSFA and our members have been asked many questions about Infectious Salmon Anemia. In the hope of clarifying some of the misinformation circulating on this topic, the BCSFA has produced a short Q&A on ISA, explaining what it is and what we know about it in British Columbia.
Next week, the Cohen Commission will reconvene its hearings for three days of evidence regarding ISA. The BCSFA will be present at those hearings, but has already submitted all of the information it has in its possession regarding the testing of its fish for the virus. All of those tests have been negative. We look forward to hearing the testimony of experts however, who may be able to add more insight to this topic.
Q&A – ISAv
What is ISA?
Infectious Salmon Anemia (ISA) is a diseased caused by the Infectious Salmon Anemia virus. It is a viral disease that principally affects Atlantic salmon – the species most commonly farmed in British Columbia. There has never been a confirmed case of ISA in B.C. While Atlantic salmon are particularly susceptible to the disease, Pacific salmon have shown to be at low risk [1].
Is ISA/ISAv in British Columbia?
Because ISA has the potential to cause mortality in Atlantic salmon, members of the BCSFA have participated in regular testing of our farm-raised fish for ISA, and nearly 5,000 tests so far have shown no ISA in any farmed fish. The Canadian Food Inspection Agency has reviewed this testing and reported that it’s confident in the results, confirming that there is no ISA in BC. Our farms continue to see good fish health and high survival rates indicating the absence of ISA.
There has been some limited testing of wild fish by government regulators which has also shown no ISA presence in British Columbia.
Rumors of ISA being present in BC are false. ISA is not present in BC. The Canadian Food Inspection Agency who has the national and international responsibility for the diagnosing of this disease has not been able to confirm that ISA is present in BC in either wild or farmed salmon. No laboratories in Canada or Norway have been able to isolate the ISA virus from BC fish.
How can some testing for ISA be presumptively positive while results are confirmed negative?
Scientists use Polymerase chain reaction (PCR) as a screening tests to detect the possible presence of viruses such as ISA. As these tests are only screening tests, presumptive positive results need to be further evaluated with confirmatory testing before a positive diagnosis can be made. That additional confirmatory testing includes isolating the suspected virus or sequencing of the virus. Both of these confirmatory tests have been applied to the samples which had a presumptive diagnosis but all were negative. This means that the ISA virus has not been diagnosed in BC.
For more information about testing, see this post from the Department of Fisheries and Oceans: http://www.dfo-mpo.gc.ca/media/back-fiche/2011/20111108-eng.htm
Could ISAv be on salmon farms?
Based on the high survival rate of our farm fish and the regular testing that has occurred on our farms, there is no reason to believe that ISA is on salmon farms. Because we have a well-developed health profile of our farmed fish and since Atlantic salmon are susceptible to the disease, experts feel our farms are good sentinels for disease that may be affecting wild salmon – like the canary in a coal mine. Given the experience of ISA infection in other salmon-farming jurisdictions, this is not something that would occur on our farms without us finding significant mortality.
To reduce the chance of ISA or other disease being introduced to British Columbia, any imports of fish eggs, milt and broodstock have been highly regulated. Along with disinfection and quarantine requirements, these products also have to be sourced only from ISA-free facilities and geographic areas.
Is ISAv a food health issue?
ISA is a viral disease of salmon and poses no risk to human health.
[1] Pacific salmon species are at relatively low risk should ISA spread to the west coast of North America" (Rolland and Winton 2003).
Rolland, J.B., Winton, J.R. 2003. Relative resistance of Pacific salmon to infectious salmon anaemia virus. Journal of Fish Diseases 26(9):511-520.
For your convenience here are links to News Releases from December 2, 2011:
To read the press release from CFIA, click here.
To read the Ministerial statement from the DFO, click here.
To read the backgrounder on how DFO protects aquaculture species from disease, click here .
To read the BCSFA's press release regarding these results, click here.
