Re: Infectious Salmon Anaemia found in Pacific Salmon
Published Date: 2011-10-19 02:53:31
Subject: PRO/AH> Infectious salmon anemia - Canada: (BC) Pacific, 1st rep
Archive Number: 20111019.3120 INFECTIOUS SALMON ANEMIA - CANADA: (BRITISH COLUMBIA) PACIFIC, 1ST
REPORT
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[1]
Date: Tue 18 Oct 2011
Source: Metro News [edited]
http://www.metronews.ca/vancouver/local/article/999363--salmon-disease-found-in-pacific-fish
A highly infectious disease recently found in salmon could have
profound effects on both the British Columbia salmon industry and
local aboriginal communities, a Simon Fraser University [SFU]
professor warned yesterday [17 Oct 2011].
SFU researchers Richard Routledge and Nicole Gerbrandt, in
collaboration with independent biologist Alexandra Morton, found the
1st-ever traces of the disease, infectious salmon anemia (ISA), in
wild sockeye salmon in the North Pacific Ocean. 2 out of 48 salmon
smolts [young salmon] collected from Rivers Inlet were infected with
the virus, and researchers fear it could spread.
[byline: Kendra Wong]
--
communicated by:
ProMED-mail rapporteur Mary Marshall
******
[2]
Date: Mon 17 Oct 2011
Source: PhysOrg.com, Simon Fraser University (SFU) report [edited]
http://www.physorg.com/news/2011-10-lethal-atlantic-virus-pacific-salmon.html
The highly contagious marine influenza virus, infectious salmon anemia
(ISA) has for the 1st time been officially reported after being found
in the Pacific on BC's central coast.
Now it threatens both wild salmon and herring, say biologist Alexandra
Morton and Simon Fraser University professor Rick Routledge, whose
laboratory led to the discovery of ISA in BC salmon smolts.
Morton is calling for removal of Atlantic salmon from BC salmon farms.
"Loosing a virus as lethal and contagious as ISA into the North
Pacific is a cataclysmic biological threat to life," said Morton. "The
European strain of ISA virus can only have come from the Atlantic
salmon farms. The European strain ISA infected Chile via Atlantic
salmon eggs in 2007." Morton says ISA was first found in Norway in
1984. "Since then, there have been lethal outbreaks in every important
salmon-farming region around the globe, with the exception -- or so we
thought -- of BC. Now we know for sure that it has hit BC.
"The Cohen Inquiry revealed ISA signs have been reported in farm
salmon in BC since 2006. The fisheries ministers have written me
repeatedly that BC is safe from ISA. Clearly they are not in control
of the situation. "If there is any hope, we have to turn off the
source: Atlantic salmon have to be immediately removed."
The virus was found in 2 of 48 sockeye smolts collected as part of a
long term study, led by Routledge, on the collapse of Rivers Inlet
sockeye populations.
Dr Fred Kibenge of the ISA reference laboratory at the Atlantic
Veterinary College in Prince Edward Island made the diagnosis and
notified the Canadian Food Inspection Agency (CFIA) of the positive
results for the European strain of ISA virus.
Says Routledge: "ISA is a deadly exotic disease which could have
devastating impacts on wild salmon and the many species that depend on
them throughout much of British Columbia and beyond.
"The combined impacts of this influenza-like virus and the recently
identified parvovirus that can suppress the immune system could be
particularly deadly."
Morton adds: "The New York Times reported from Chile that the Chilean
aquaculture industry suffered more than USD 2 billion in losses, saw
its production of Atlantic salmon fall by half, and jobs were lost."
"A scientific study concluded that salmon eggs shipped from Norway to
Chile are the 'likely reason' for the outbreak of the virus in Chile
in 2007. And nearly 40 million Atlantic salmon eggs have been imported
into BC since 1986."
"This is devastating news and something I worked hard to prevent. This
has international implications throughout the North Pacific."
Routledge concurs that the only plausible source for the European
strain of ISA virus that he found on BC's Central Coast is the
Atlantic salmon farms.
Rivers Inlet is on the BC Central Coast in the heart of the Great Bear
Rainforest -- 100 km [62 mi] north of a cluster of Norwegian-owned
Atlantic salmon feedlots off Port Hardy and 140 km [87 mi] south of
Marine Harvest's feedlots near Klemtu.
"The potential impact of ISA cannot be taken lightly," said Routledge.
"There must be an immediate response to assess the extent of the
outbreak, determine its source, and to eliminate all controllable
sources of the virus -- even though no country has ever eradicated it
once it has arrived."
Routledge is a fish-population statistician who was a founding member
of the Pacific Fisheries Resource Conservation Council. Morton
received an honorary degree from SFU for her work linking sea lice
infestation in wild salmon to fish farming in the Broughton
Archipelago, which has sparked international attention.
The 2 researchers said that the federal Cohen Commission on the
decline of sockeye salmon runs in the Fraser River was told that more
than 1000 cases of ISA-type lesions have been reported on BC salmon
farms since 2006 -- yet no suspect cases or diagnoses of ISA were
reported to the Canadian Food Inspection Agency, or to the World
Organization for Animal Health (known as OiE, from its former name of
Office International des Epizooties).
Morton, who long ago urged the federal government to close the border
to Atlantic salmon eggs as the virus spread in fish farms around the
world, says the fact that ISA was found in smolts suggests it has been
loose in the Pacific for several years. [At least it has been loose
for some time, an exact amount of time is unknown. - Mod.TG]
"Government and industry are clearly not testing effectively. There
needs to be an international volunteer epidemiological team formed
right now. No one party can own the data. We have to use everything we
know to try and contain this."
The researchers say if there is any hope of controlling this disease
it must be addressed at the source. The virus is also prone to
mutating into increasingly virulent forms.
ISA virus and BC salmon farms
-----------------------------
ISA has only appeared where salmon are raised in aquaculture and has
spread worldwide since first being reported in Norway in 1984. ISA can
infect herring, as well as, salmon. ISA was first reported in Eastern
Canada in 1996 and continues to cause problems there.
In 2007, ISA began in a non-lethal form in Chile and became a virulent
epidemic killing 70 per cent of the farm salmon. Chile does not have
wild salmon.
In January 2009, a group of Canadian scientists, including David
Suzuki, signed a letter warning the Canadian fisheries minister of the
risks of introducing ISA into BC. Ex-minister Gale Shea refused to
acknowledge that ISA reached Chile in eggs, although Cermaq, a
state-controlled Norwegian aquaculture company that has become one of
the principal exporters of salmon from Chile, endorsed a scientific
study concluding that salmon eggs shipped from Norway to Chile were
the 'likely reason' for the outbreak of the virus in Chile in 2007.
ISA is known to exist in a non-lethal state, causing low mortalities
on salmon farms and then mutate into highly virulent strains when
contained in salmon farms.
Forty million Atlantic salmon eggs have been introduced into BC since
1986. The Fish Health Certificate that must be signed by the foreign
hatcheries does not specifically request ISA virus reporting (Manual
of Compliance, Ottawa 2004, page 51).
Fisheries and Oceans did not require reporting of ISA virus on salmon
farms, but the Canadian Food Inspection Agency intervened in January
2011 and made ISA virus a reportable disease
(
http://www.gazette.gc.ca/rp-pr/p2/2010/2010-12-22/html/sor-dors296-eng.html#REFa;
see "Regulatory Impact Statement" 2/3 down the site.)
As a participant of the Cohen Inquiry, Alexandra Morton read the BC
Ministry of Agriculture and Lands disease reports and found over 1100
reports of "classic" ISAV lesions in farm salmon.
Justice Cohen was petitioned by her lawyer, Greg McDade, to allow her
to report these to the Canadian Food Inspection Agency, but the CFIA
appear to have merely called the fish farmers and asked if they had
ISA virus; no testing was done.
In 2004, Dr Laura Richards, director general of DFO [Department of
Fisheries and Oceans] Science, Pacific Region, successfully petitioned
on behalf of the fish farm industry to waive the Canadian Fish Health
Protection Regulations to allow Atlantic salmon eggs from a hatchery
that does not meet Canadian regulations (CohenCommision.ca Exhibit no
1683).
Since then all Atlantic salmon eggs have come from this hatchery. In
2005 an entire shipment was destroyed due to viral concerns
(CohenCommission.ca Exhibit no 1684). There is no record of testing
the eggs that arrived in BC from the same hatchery the previous month
(CohenCommision.ca Exhibit no 1683).
More information: Report on ISA to World from Dr Fred Kibenge,
University of Prince Edward Island
http://www.oie.int/eng/A_aquatic/Docs/Presentations/1.11Kibenge.ppt.
--
communicated by:
ProMED-mail
[A HealthMap/ProMED-mail interactive map of British Columbia can be
seen at
http://healthmap.org/r/1lEe. - Sr.Tech.Ed.MJ
This may be extremely important and clearly shows a movement of the
disease. It will be interesting to see the response of the government
with regard to the Atlantic fish.
This highly contagious disease can be insidious, with an initially low
mortality rate; however, the cumulative mortality can sometimes exceed
90 per cent if the disease remains unchecked. Infectious salmon anemia
was first described in Norway in 1984, and it continues to be a
problem in that country despite control measures. Since the late
1990s, outbreaks have also been reported in other locations. This
disease devastated the salmon industry of the Faroe Islands in 2000,
and an epizootic in Scotland in 1998-1999 cost an estimated USD 32
million to eradicate. ISA has been a recurring problem in Chile, the
Cobscook Bay in Maine, and the Bay of Fundy in New Brunswick, Canada.
In New Brunswick, it results in annual losses of about USD 4.8-5.5
million to farmers, and millions of fish have been culled in control
efforts. New outbreaks can also occur in areas where this disease was
absent for many years. In 2009, an outbreak was reported again in
Scotland.
Understanding of the epidemiology of ISA is still incomplete, which
complicates its control. The reservoirs for the virus are not known,
but experiments have shown that several species of salmonids can carry
virulent ISA viruses asymptomatically. These viruses could cause
outbreaks if they are transmitted to farmed Atlantic salmon.
Noncultivable, apparently nonpathogenic, isolates have also been
detected in wild salmonids. Small changes in these viruses, analogous
to the mutations that allow low pathogenicity avian influenza viruses
to become highly pathogenic, may allow them to become more virulent.
Recent evidence also suggests that some ISA viruses may cause illness
in species other than Atlantic salmon. One isolate has been linked to
illness among farmed Pacific coho salmon in Chile, and a highly
virulent strain can cause disease in experimentally infected rainbow
trout.
Infectious salmon anemia virus (ISAV) is a member of the genus
_Isavirus_ in the family Orthomyxoviridae. Hemorrhagic kidney syndrome
is an old name for the disease in Atlantic salmon. In coho salmon, it
has also been called icterus syndrome.
The 2 major lineages of ISAV are the European genotype (or genotype I)
and the North American genotype (or genotype II).
Epidemiological studies suggest that ISAV can be transmitted
indirectly in water and on fomites, as well as by close contact
between fish. Horizontal transmission can occur in both freshwater and
seawater. Sea lice (_Lepeophtheirus salmonis_ and _Caligus_ sp.) may
be mechanical vectors. These parasites could also increase the
susceptibility of fish by increasing stress. In the laboratory, ISAV
remained infective when held at 15 deg C (59 deg F) for 10 days or 4
deg C (39 deg F) for 14 days. There was a 3 log (1000-fold) reduction
in the viral titer when ISAV was held at 4 deg C (39 deg F) for 4
months. It was stable between pH 5.7 and pH 9.0. Because the virus's
survival can also be affected by factors such as UV irradiation and
components in the water which can either bind or inactivate it, it is
difficult to estimate the length of time before ISAV is inactivated in
nature.
Infectious salmon anemia should be a consideration in Atlantic salmon
with increased mortality and signs of anemia, or lesions consistent
with this disease. It should always be investigated if the hematocrit
is less than 10 per cent.
The differential diagnoses for infectious salmon anemia include other
causes of anemia and hemorrhages, as well as winter ulcer and
septicemias caused by _Moritella viscosa_.
Outbreaks of infectious salmon anemia can be diagnosed by virus
isolation, the detection of antigens and RT-PCR. A few isolates from
sick salmon have been difficult to culture, even when viral nucleic
acids can be found. The avirulent isolates carried subclinically in
wild salmonids can usually be detected only by RT-PCR.
Portions of this comment have been extracted from
http://www.cfsph.iastate.edu/Factsheets/pdfs/infectious_salmon_anemia.pdf
- Mod.TG]
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