DFO Statement, Backgrounder and CFIA Release, Nov. 9, 2011

Read DFO Statement, Backgrounder & CFIA Release, Nov 9

Statement from the Federal Minister of Fisheries and Oceans Canada, Keith Ashfield and British Columbia Minister of Agriculture, Don McRae on new test results indicating that there are no confirmed cases of ISA in British Columbia Salmon
Fisheries and Oceans Canada, November 9, 2011

Ottawa, Ontario – Federal officials from the Canada Food Inspection Agency, along with officials from Fisheries and Oceans Canada and British Columbia’s Chief Veterinary Officer, provided a technical briefing yesterday on new test results indicating that there are no confirmed cases of Infectious Salmon Anaemia in British Columbia salmon.

The National Reference Laboratory has completed Polymerase Chain Reaction (PCR) testing, a sensitive but preliminary test, that has shown no presence of ISA in the samples provided; this is the same process that was reportedly used in the original claims of positive test results by individual sources. Officials provided information on the extensive actions underway by the Government of Canada to investigate claims about the presence of the disease, the timeline of test results, and the proper, science-based requirements for testing.  Officials also indicated that there will be investigations into the collection, handling, transportation and storage of samples by other sources that led to the original claims.

Minister Ashfield said: “It has been a difficult few weeks for the fishing industry in
British Columbia, and across the country, while waiting for these preliminary test results to come back. Because some have chosen to draw conclusions based on unconfirmed information, this has resulted in British Columbia’s fishing industry and Canada’s reputation being put at risk needlessly.

“Our government takes the health of our fisheries very seriously. We have taken appropriate and immediate action to follow up on the allegations of the presence of ISA in BC waters.  We can now confirm that, preliminary analysis, using proper and internationally recognized procedures, has found that none of the samples has tested positive for ISA. In recent years, over 5000 fresh, properly stored and processed salmon have been tested by the BC government and Fisheries and Oceans Canada and there has never been a confirmed case of ISA in British Columbia salmon. An active, science-based sampling program continues for both farmed and wild salmon.”

Minister McRae noted: “It is vitally important that we base our policy decisions on sound science so as to preserve and protect BC’s reputation as a reliable supplier of high quality seafood to the world. This is particularly true for the dozens of coastal communities that rely on wild and farmed fisheries to feed their families and maintain their way of life. Reckless allegations based on incomplete science can be devastating to these communities and unfair to the families that make a living from the sea. Since Premier Clark is currently on a trade mission to China, I have personally asked her to reassure our valued trading partners that now as always BC can be relied upon as a supplier of safe, sustainable seafood.”

Minister Ashfield continued: “Canadian and international partners can be confident that current practices and procedures to protect our wild and farmed salmon industries from disease are in place and working.  I will be communicating directly with concerned parties domestically and internationally over the coming weeks to reassure my counterparts, the fishing industry and consumers that BC salmon is healthy and safe."

Related information:Infectious Salmon Anemia (ISA) Virus – Accepted Testing Methods
Fisheries and Oceans Canada,  November 2011

Searching for a Unique Genetic Fingerprint

Every virus has a unique genetic fingerprint.  Polymerase chain reaction (PCR) is a technique that focuses on specific portions of this fingerprint so that they may be detected and identified. Detection of this small genetic target of viral RNA constitutes a presumptive positive test result.

The PCR is a highly sensitive test that sometimes produces false positive results; because of this, these presumptive positive samples require further confirmatory testing to ensure their validity.

Confirmatory testing can take two forms:  First, there should be an attempt to isolate the virus from host tissues using cell culture. Cell culture allows the virus to infect the cells and multiply as it would in the host fish. It is possible to have a positive PCR test and ultimately a negative cell culture result.  Cell culture also requires that a minimum dose of live virus be present in the test sample and can take up to four weeks to have results from this test.

And second, the virus needs to be properly identified and this is usually done using conventional PCR techniques to amplify larger and different portions of the viral genes which are then sequenced and compared to the unique ISA fingerprint.

To date, no attempts to isolate the suspect ISA virus in cell culture have been successful by any laboratory; nor has any sequencing data been produced. Thus, there have been no confirmed findings of ISA in the samples.

Tissue Quality

There are several factors which must be considered in the testing.   

First, the nature of the PCR test requires the sample to be fresh or well preserved.  Fish should be collected live, moribund, or as fresh mortalities (within 24 hours).   Because both host (fish) and viral RNA degrades rapidly after death, virus detection can quickly become impossible by PCR or any other accepted test methods. Fish can be frozen to preserve the RNA, but tissue and virus degradation occurs even at -20 degrees Celsius. Storage at -70 degrees Celsius, or in a specialized storage preservative known as an “RNAlater,” is required for long term preservation.

Second, because the virus is not distributed equally in all parts of the fish, the heart and kidney are the best organs to test. Gills can also be tested. However detection in gills indicates viral particles are in the environment. It does not mean infection of the host. Finally, sample size should  be large enough for testing. A sample the size of a grain of rice allows for both PCR & molecular confirmatory tests (sequencing). Significantly larger amounts are needed for cell culture and archiving for future reference and testing.

Because RNA degrades rapidly, an extra test, called the “reference gene assay”, is conducted on the original extract.  The result of this assay indicates the level of degradation by comparing it to a well preserved sample of the same species. As mentioned, if the RNA has substantially degraded, neither a PCR nor any other approved testing method can determine the presence or absence of the virus with any degree of confidence.

No Confirmed Cases of Infectious Salmon Anaemia in British Columbia
Canadian Food Inspection Agency, Nov. 9, 2011

November 9, 2011: Based on analysis conducted by the Canadian Food Inspection Agency (CFIA), in close collaboration with Fisheries and Oceans Canada (DFO), the Province of British Columbia and the Atlantic Veterinary College, there have been no confirmed cases of infectious salmon anaemia in wild or farmed salmon in BC.

Testing in support of this investigation has been ongoing since mid-October, when a laboratory at the Atlantic Veterinary College reported that it had detected the virus.

DFO has tested all 48 samples received as part of the original reports and the results are all negative for the virus. These results are consistent with the findings of an independent laboratory in Norway, which also tested samples associated with this investigation and provided a report to the CFIA.

Additional testing continues and results will be provided when ready.

As part of the investigation, the CFIA and DFO are also looking at how the samples were collected, handled, transported and stored.

In recent years, over 5,000 wild and farmed salmon in BC have been tested by the Federal Government and the Province of BC and none have ever tested positive for the disease.

The CFIA, in collaboration with DFO and the Province of BC, is assessing the current testing levels for this virus in both wild and aquaculture populations in BC and will increase surveillance activities as required.

Infectious salmon anaemia poses no risk to people.

In Canada, infectious salmon anaemia is a "federally reportable disease" in Canada. This means that all suspected or confirmed cases must be immediately reported to the CFIA.

Under the CFIA's National Aquatic Animal Health Program, suspected federally reportable diseases such as infectious salmon anaemia must be confirmed at the DFO national reference laboratory.

For more information on infectious salmon anaemia, visit www.inspection.gc.ca/aquatic or call 1-800-442-2342.