Viral Hemorrhagic Septicemia (VHS)

What is Viral Haemorrhagic Septicaemia (VHS)?

VHS is an infectious disease of finfish caused by the viral haemorrhagic septicaemia virus.

Where is VHS found?

There are several known strains of VHS virus that affect many freshwater and marine fish species in the northern hemisphere of the world. In Canada, VHS virus strains are found in the Pacific and Atlantic oceans and their estuaries, and more recently in some of the Great Lakes and their tributaries.

The first occurrence of VHS in Canadian freshwater was detected in Lake Ontario in 2005.

Fisheries and Oceans Canada (DFO) has determined that the VHS virus detected in the Great Lakes is a North American type (IV), and most closely related to the strain found on the Atlantic coast of Canada. 

How is VHS transmitted and spread?

VHS infection is known to spread from fish to fish in one of two ways:  by feeding upon diseased fish or by living in contaminated water. Water becomes contaminated when infected fish shed the virus through their urine or when infected fish die and decompose releasing the virus. People can spread the virus by moving contaminated fish, water, boats and other equipment between bodies of water. Fish-eating birds, such as herons, may also transmit the virus.

Fish do not have to be sick to transmit the virus. Healthy fish can also carry and shed the virus.

Is VHS a public health risk?

No, VHS does not pose a human health risk.

What are the clinical signs of VHS?

Diseased freshwater fish may exhibit any or all of the following signs of VHS:

• bulging eyes;
• pale gills;
• signs of bleeding around the eyes, bases of the fins, sides and head;
• dark colouration;
• distended (fluid-filled) belly;
• gasping at the surface;
• corkscrew swimming behaviour; and,
• high death rate.

How is VHS diagnosed?

VHS may be suspected based on the clinical signs. Diagnosis must be confirmed by laboratory tests.

How is VHS treated?

There is no specific treatment for VHS. However, various control measures, such as fish and water movement restrictions and disinfection of fish eggs and equipment, can be implemented in order to minimize spread.

What roles and responsibilities exist to prevent VHS?

A fish die-off or fish with signs of VHS should immediately be reported to local fisheries authorities. The sooner they are alerted, the quicker they can collect samples for analysis by qualified fish health laboratories.

Do not move or transfer any fish from one body of water to another. Anyone wishing to move live fish from the Great Lakes (especially from areas noted as positive for the VHS virus) to another body of water should contact their local fisheries authority or Fisheries and Oceans Canada.

For more information:

CFIA - Aquatic Animal Health Division; Ottawa
Telephone:  613-221-1399
http://www.inspection.gc.ca

DFO - National Aquatic Animal Health Registry; Ottawa
Telephone:  613-990-0292
http://www.dfo-mpo.gc.ca

Ontario Ministry of Natural Resources - Natural Resource Information Centre;
Telephone: 1-800-667-1940
http://www.mnr.gov.on.ca