Infectious Haematopoietic Necrosis - Fact Sheet

What is infectious haematopoietic necrosis?

Infectious haematopoietic necrosis is an infectious disease of finfish. It is caused by the infectious haematopoietic necrosis virus, which belongs to the family Rhabdoviridae.

What species of finfish can be infected by infectious haematopoietic necrosis?

Each species of finfish may have several common names, but only one common name is listed.

Species susceptible to infectious haematopoietic necrosis that exist in the natural environment in Canada include:

• Acipenser transmontanus (white sturgeon)
• Aulorhynchus flavidus (tube snout)
• Clupea pallasii (Pacific herring)
• Cymatogaster aggregata (shiner perch)
• Esox lucius (northern pike)
• Gadus morhua* (Atlantic cod*)
• Lota lota* (burbot*)
• Oncorhynchus clarkii (cutthroat trout)
• Oncorhynchus gorbuscha (pink salmon)
• Oncorhynchus keta (chum salmon)
• Oncorhynchus kisutch (coho salmon)
• Oncorhynchus mykiss (rainbow trout)
• Oncorhynchus nerka (sockeye salmon)
• Oncorhynchus tshawytscha (chinook salmon)
• Salmo salar (Atlantic salmon)
• Salmo trutta (brown trout)
• Salvelinus alpinus (arctic char)
• Salvelinus fontinalis (brook trout)
• Salvelinus namaycush (lake trout)
• Thymallus arcticus* (arctic grayling*)

Species susceptible to infectious haematopoietic necrosis virus that do not exist in the natural environment in Canada include:

• Oncorhynchus rhodurus (amago salmon)
• Oncorhynchus masou (masu salmon)
• Plecoglossus altivelis (ayu sweetfish)
• Salvelinus leucomaenis* (whitespotted char*)

Note: Species identified with an asterisk have not been confirmed as susceptible to infectious haematopoietic necrosis virus.

Is infectious haematopoietic necrosis a risk to human health?

No. The causal agent of infectious haematopoietic necrosis is not a risk to human health.

What are the signs of infectious haematopoietic necrosis?

Infectious haematopoietic necrosis is a cause of death in

• young finfish raised in freshwater hatcheries
• young juveniles recently introduced into seawater (death rates reach 100 percent over a short period of time)
• older finfish raised in seawater (death rates range from 20 percent to 100 percent over an extended period of time)

Affected finfish held in freshwater may exhibit any of the following signs:

• behaviour
  • loss of appetite
  • abnormal swimming patterns (slow spirals, flashing or bouts of erratic swimming)
  • floating "belly up"
• appearance
  • bulging eyes
  • pale gills
  • areas of pinpoint bleeding at base of fins, in mouth, head, anus
  • dark skin colouration (in younger finfish)
  • swollen belly (may be filled with fluid)
  • white to yellowish fluid may be present in stomach and intestines
  • trailing fecal casts may be present in young finfish
  • swelling of the kidney
  • areas of pinpoint bleeding in muscle tissues and internal organs

Infected finfish held in seawater may exhibit any of the following:

• behaviour
  • abnormal swimming patterns (slow swimming at the surface)
• appearance
  • dark skin colouration
  • pale or brown gills
  • fluid present in the belly
  • areas of pinpoint bleeding in muscle tissues and in tissues surrounding internal organs

Is infectious haematopoietic necrosis virus found in Canada?

Yes. In Canada, infectious haematopoietic necrosis virus has been found in wild finfish in the Pacific Ocean watershed of British Columbia. The virus has also occurred sporadically in finfish reared in aquaculture sites in the Pacific Ocean watershed of British Columbia.

How is infectious haematopoietic necrosis virus spread?

Infectious haematopoietic necrosis virus is spread between finfish by

• contaminated equipment, and
• contaminated water.

People can spread infectious haematopoietic necrosis virus by moving any of the following:

• infected live or dead finfish,
• contaminated equipment, or
• contaminated water.

How is infectious haematopoietic necrosis diagnosed?

Diagnosing infectious haematopoietic necrosis requires laboratory testing. Not all infected finfish show signs of disease.

How is infectious haematopoietic necrosis treated?

There are no treatments currently available for infectious haematopoietic necrosis. However, vaccines are available to prevent the disease.

What measures can be taken to prevent the introduction and spread of infectious haematopoietic necrosis virus?

If you frequently handle or work with finfish, be aware of the clinical signs of infectious haematopoietic necrosis.

Do not import live infected finfish into Canada.

• An import permit is required from the CFIA for certain species of finfish as of December 2011.
• People bringing finfish into Canada should check other federal, provincial and/or territorial requirements before entering the country.

Do not introduce live finfish from another country into the natural waters of Canada.

• People releasing finfish into the natural waters or in rearing facilities within Canada should check if federal or provincial and/or territorial permits are required.

If you frequently handle or work with finfish, be aware of where infectious haematopoietic necrosis occurs in your area.

• A federal, provincial and/or territorial permit or licence may be required to relocate finfish within Canada.

Do not use finfish that were bought in a grocery store as bait for catching finfish or other aquatic animals.

When cleaning and gutting finfish, dispose of all finfish wastes in your municipal garbage.

The Canadian Food Inspection Agency (CFIA) recommends that you do not visit Canadian aquaculture sites, zoos or aquariums for 14 days if you have travelled to another country and

• visited an aquaculture site, or
• had contact with wild finfish.

Wash and disinfect the footwear you wore to the site or when you had contact with wild finfish. Also wash your clothing thoroughly and dry it at a high temperature.

What is done to protect Canadian aquatic animals from infectious haematopoietic necrosis?

Infectious haematopoietic necrosis is a reportable disease in Canada. This means that anyone who owns or works with aquatic animals, who knows of or suspects infectious haematopoietic necrosis in their fish, is required by law to notify the CFIA.

If infectious haematopoietic necrosis is found outside of known infected areas in Canada, the CFIA would control its spread by implementing disease response activities. These may include

• controlling the movements of infected animals that people own or work with
• humanely destroying infected animals
• cleaning and disinfecting

The control measures chosen would depend on the situation.

What do I do if I think finfish that I am raising or keeping have infectious haematopoietic necrosis?

If you suspect a finfish that you are raising or keeping may have infectious haematopoietic necrosis, you are required under the Health of Animals Act to immediately notify the CFIA.

How do I get more information

For more information about reportable diseases, visit the Aquatic Animal Health page, contact your local CFIA Animal Health Office, or your CFIA Area office:

• Atlantic: 506-777-3939
• Quebec: 514-283-8888
• Ontario: 226-217-8555
• West: 587-230-2200