Published Date: 2012-12-20 15:39:18
Subject: PRO/AH> Infectious salmon anemia - Canada (05): (NF)
Archive Number: 20121220.1461133
INFECTIOUS SALMON ANEMIA - CANADA (05): (NEWFOUNDLAND)
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: 18 Dec 2012
Source: Metro News [edited]
The Canadian Food Inspection Agency has confirmed a viral outbreak in salmon at a fish farm in southern Newfoundland.
The provincial government says the unnamed site has been in quarantine since late last month [November 2012], when the presence of infectious salmon anemia was 1st suspected.
The virus is not considered harmful to humans but is a risk to other fish farms in the region.
ProMED-mail from HealthMap alerts
Date: 19 Dec 2012
Source: OIE [edited]
Information received on 19 Dec 2012 from Dr Brian Evans, chief food safety officer/chief veterinary officer, Office of the President, Canadian Food Inspection Agency, Ottawa, Canada
Summary: report type: immediate notification
Date of start of the event: 26 Nov 2012
Date of pre-confirmation of the event: 4 Dec 2012
Report date: 18 Dec 2012
Reason for notification: new pathogen strain or disease manifestation
Manifestation of disease: clinical disease
Causal agent: Infectious salmon anemia virus
Nature of diagnosis: laboratory (advanced)
New outbreaks (1)
Outbreak 1: Bay d'Espoir, Newfoundland
Date of start of the outbreak: 26 Nov 2012
Outbreak status: continuing (or date resolved not provided)
Epidemiological unit: farm
Water type: salt water
Population type: farmed
Production system: semi-open
Affected animals: Atlantic salmon
Species: (_Salmo salar_)
Morbidity: 2 (scale 0 to 5)
Mortality: 2 (scale 0 to 5)
Affected population: Atlantic salmon, vaccinated against ISA, about 3.8 kg in size. Concurrent diseases are present (bacterial kidney disease and infestation with sea lice), so the case-specific mortality figure may represent an overestimate. Mortality rates appear to be declining. Water temperatures are also declining and are 2 C at the surface and 8 C at a depth of 15 meters.
Summary of outbreaks:
Total outbreaks: 1
Total animals affected: species: Atlantic salmon (_Salmo salar_)
Susceptible: 351 000
Outbreak statistics: species: Atlantic salmon (_Salmo salar_)
Apparent morbidity rate: 2.41 per cent
Apparent mortality rate: 2.41 per cent
Apparent case fatality rate: 100.00 per cent
Proportion susceptible animals lost* 2.41 per cent
*Removed from the susceptible population through death, destruction, and/or slaughter
Source of the outbreak(s) or origin of infection: unknown or inconclusive
Epidemiological comments: The identified strains have not been reported before. The population is infected with at least 2 strains of ISAV (non-HPR0); one is most similar to HPR6, the other does not demonstrate any particular similarity to any previously described HPR type. Both are considered to be North American as opposed to European strains. It is hypothesized that incursion into this farm may have originated from infected wild finfish. The next report will be submitted when fish are removed from the farm.
Measures applied: movement control inside the country, tracing forward, tracing back, quarantine, surveillance outside containment and/or buffer zone, official disposal of carcasses, by-products and waste, surveillance within containment and/or buffer zone, no vaccination, no treatment of affected animals
Measures to be applied: disinfection of infected premises/establishment(s), official destruction of clinically diseased aquatic animals
New pathogen strain or disease manifestation:
Description of new strain: the population is infected with at least 2 strains of ISAV (non-HPR0); one is most similar to HPR6; the other does not demonstrate any particular similarity to any previously described HPR type. Both are considered to be NA as opposed to European strains.
New disease manifestation:
Diagnostic test results:
Laboratory name and type / Species / Test / Test date / Result
Department of Fisheries and Oceans (DFO), Gulf Fisheries Centre (National laboratory) / Atlantic salmon (_Salmo salar_) / real-time reverse transcriptase/polymerase chain reaction (RRT-PCR) / 17 Dec 2012 / Positive
Department of Fisheries and Oceans (DFO), Gulf Fisheries Centre (National laboratory) / Atlantic salmon (_Salmo salar_) / RT-PCR / 4 Dec 2012 / Positive
Department of Fisheries and Oceans (DFO), Gulf Fisheries Centre (National laboratory) / Atlantic salmon (_Salmo salar_) / virus isolation / 14 Dec 2012 / Positive
Future reporting: the event is continuing. Weekly follow-up reports will be submitted.
[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 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.
ISA is a disease of Atlantic salmon (_Salmo salar_) caused by an orthomyxovirus and affects mainly fish maintained in marine water or exposed to the sea. The disease is systemic and lethal, characterized by severe anemia and hemorrhages in several organs. It is a disease of great economic impact for the salmon industry.
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.
Infectious salmon anemia is an OIE-listed disease as well as a regulated aquatic animal disease in Canada under the Health of Animals Act and supporting regulations that are administered by the Canadian Food Inspection Agency (CFIA).
Portions of this comment have been extracted from http://www.cfsph.iastate.edu/Factsheets/pdfs/infectious_salmon_anemia.pdf.
A photograph of an Atlantic salmon may be found at http://www.tdsfb.org/pictures/pics640/lun19nov05(6).htm.
Newfoundland may be found on the interactive HealthMap/ProMED-mail map at http://healthmap.org/r/4zc7. - Mod.TG]