INFECTIOUS SALMON ANEMIA - CANADA (03): (BRITISH COLUMBIA)
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A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases <http://www.isid.org>
Date: Thu 3 Nov 2011
Source: Mainstream Canada [edited]
<http://www.mainstreamcanada.ca/no-conclusive-evidence-isa-virus-bc-fish-after-independent-retesting>
Independent tests at one of the world's top ISA [infectious salmon anemia] virus research labs reanalyzed 48 samples of Pacific salmon and did not find conclusive evidence that any of the fish had ISA.
This week [of 31 Oct 2011], Dr Are Nylund at the University of Bergen
(Norway) reanalyzed tests done last month [October 2011] on 48 Pacific salmon by Dr Fred Kibenge at the University of Prince Edward Island (UPEI). After extensive re-testing, Nylund did not find conclusive evidence that the fish had the infectious salmon anemia (ISA) virus.
Sampling for this virus is extremely sensitive, so Dr Nylund tested and retested the samples. One of the samples was tested 33 times; in that sample he found one weak positive result and 32 negative results.
In a recent interview, of which Mainstream has obtained a copy [see <http://tinyurl.com/66kljmy>], Dr Nylund explained, "The test material we received was of poor quality, and all tests were negative except the one which was weakly positive. This means that I could not confirm the results from Kibenge, since he found 2 clearly positive findings and concluded that this had European origin."
Dr Nylund continued, "This also means that a virus having genetic similarities with ISA or something totally different may be picked up by the test. Therefore we need to sequence/genotype the virus to provide serious comment on the origin." He said the findings could represent a previously unknown type of Pacific Ocean virus. "Not all ISA-type findings are described, and there are surely many we have not yet discovered," he said.
Nylund said that it's possible any newly discovered virus could have its origins in ancient evolution. "Today there are several examples of pathogens that are related and which have a North Pacific and a North Atlantic type. One example of this is the paramyxovirus," he said.
"The reason for this is that the salmon and some of its pathogens in the Pacific and Atlantic once had the same origin, but they have developed differently as they have been geographically isolated over a long time."
Thousands of farmed and wild salmon have been tested for the infectious salmon anemia virus (ISAV), in British Columbia, including more than 1200 in 2011 alone. All of those tests were negative and they show that to date, there is no ISAV in our fish, farmed or wild.
But 2 weeks ago anti-aquaculture activist Alexandra Morton claimed Pacific salmon collected by Simon Fraser University researchers had been infected with the European ISA virus. She made the claim before the tests were even concluded, spreading fear and concern without any basis in fact.
The fish were sent for re-testing to one of the world's top ISA virus research labs at the University of Bergen in Norway and those results do not support Dr Kibenge's findings, nor do they give conclusive findings on the origin of the virus.
We are glad these tests were done, as they provide a good scientific control for the results announced publicly 2 weeks ago.
Another new lab report published by Ms Morton indicates that Kibenge tested another batch of samples she submitted, and one of the 20 apparently showed a weak positive result. However, Kibenge cautioned in his report that "the presence of ISA virus sequences in the tissue samples does not imply that the subject fish had ISA or that ISA is present in the area where the subject fish were collected from."
Further genetic testing is again necessary to determine if the latest results from UPEI mean anything, or if the results were also skewed because of poor-quality samples.
Canadian Food Inspection Agency (CFIA) is doing proper tests now to determine whether it can reach the same conclusions and will be investigating the chain of custody (scientific procedure for collecting and storing samples to prevent contamination). We believe that it is more important than ever to wait for the lead agency on this file to give the final word on this issue, and for them to complete their battery of tests before jumping to any conclusions. We urge the CFIA scientists to quickly conclude their investigation and publish their findings.
Mainstream, along with the rest of the BC salmon farming industry, has offered to provide further samples for testing by CFIA and are advocating for more sampling and testing of our region's wild fish and for continuation of the surveillance program.
For more information please contact
Grant Warkentin, Communications Officer, Mainstream Canada <grant.warkentin@mainstreamcanada.com>
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Communicated by:
David E Starling, DVM
Aqueterinary Services R, PC
Veterinary Medicine for Aquatic Animals
Ames, IA 50014
USA
<aquavet@aqueterinary.com>
<http://www.aqueterinary.com>
[Infectious salmon anemia virus (ISAV) is a member of the genus _Isavirus_ in the family Orthomyxoviridae. It is an RNA virus which renders its genetic material more fragile and RT-PCR tests might turn out negative if the sample is not adequately preserved. This is a highly contagious influenza virus and further collection of fish should provide with new evidence if the disease is propagating among wild salmonids. Apparently there is new evidence of infected fish besides the 2 out of 48 mentioned (see ProMED post 20111108.3321). The results on new sampling efforts and sequencing of the eventually positive samples would clarify the situation. See also <http://www.newsdata.com/fishletter/295/1story.html>;
<http://fis.com/fis/worldnews/worldnews.asp?l=e&country=0&special=&monthyear=&day=&id=47371&ndb=1&df=0>;
<http://www.fishfarmingxpert.com/index.php?page_id=76&article_id=92821>
- Mod.PMB]
[see also:
Infectious salmon anemia - Canada (02): (BC) 20111108.3321 Infectious salmon anemia - Chile (02) 20111029.3217 Infectious salmon anemia - Canada: (BC) Pacific, 1st rep 20111019.3120 Infectious salmon anemia - Chile 20110730.2287 2010
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Infectious salmon anemia - Chile 20100820.2909 Infectious salmon anemia - Chile (02): (MA) 20101109.4064] .................................................pmb/mj/dk/ll
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