Viral hemorrhagic septicemia

Viral hemorrhagic septicemia (VHS) is a virus-induced disease that causes hemorrhaging in fish.

Viral hemorrhagic septicemia affects more than 65 species of saltwater and freshwater fish in several Northern Hemisphere countries. It affects fish of all ages and sizes.

There are four groups of viral hemorrhagic septicemia virus (I, II, III, IV). These are located in distinct geographic areas. Groups I, II and III are found mainly in Europe, while group IV is present in North America and Asia. The susceptibility of fish species to the virus differs in each group.

In Canada, the virus has been found on the Pacific coast, the Atlantic coast and in the Great Lakes. It has never been recorded in Québec.

In the Great Lakes, at least 28 species of fish are known to be susceptible to this virus. The species that are most affected are muskellunge (in French only), largemouth bass (in French only) and yellow perch (in French only). Salmonids (trout and salmon) should be less susceptible to the virus group present in this region.

Viral hemorrhagic septicemia is transmitted between fish through direct contact, predation of infected prey, or contact with contaminated water, including urine and sexual secretions. Depending on the temperature, the virus can survive in water for several days. Cold water from 2 °C to 15 °C is particularly good for survival. It enters fish through the gills and possibly through injuries on the body’s surface.

Several elements contribute to the spread of the virus:

• the natural movement of fish;
• the transfer of infected fish (bait fish, stocking, etc.);
• the transfer of contaminated water (ballast water, fish transport water, etc.);
• the use of contaminated equipment.

Fish-eating birds can also transport infected fish to uncontaminated sites. However, there is no transmission through their feces due to their high body temperature and acidity of their digestive system.

There is no cure for this contagious disease that causes the death of infected fish.

Québec’s bodies of water are environments conducive to the introduction and spread of the viral hemorrhagic septicemia virus. Cold temperatures during most of the year and the presence of vulnerable species are ideal conditions for its establishment. You can prevent its introduction and spread by applying several simple measures such as:

• Not moving live or dead fish from one body of water to another.
• Disposing of unused bait fish and carcasses of harvested fish in the trash.
• Properly cleaning your boat and equipment (PDF 371 Kb) (in French only) before going to another body of water.

Risk for wildlife health

In the Great Lakes region, the viral hemorrhagic septicemia virus has been associated with several episodes of mass fish die-offs affecting at least 14 species.

Risk for human health

Viral hemorrhagic septicemia has no impact on human health. However, it should be noted that the consumption of fish that appear ill, dying or that are found dead should be avoided, since this could entail other health risks. Furthermore, adopting some safe practices when preparing and cooking wild fish always remains relevant.

Surveillance and control

To date, no cases of viral hemorrhagic septicemia have been reported in Québec. In the years following episodes of fish mortalities caused by the virus in the Great Lakes, targeted monitoring campaigns were conducted in Québec. Details are available in the following documents (in French only): 

• Stratégie québécoise sur la santé des animaux sauvages - Rapport des activités de surveillance - 2008 (PDF 4.33 Mb)
• Stratégie québécoise sur la santé des animaux sauvages - Rapport des activités de surveillance - 2009 (PDF 7.07 Mb)
• Surveillance des maladies de la faune 2011-2014 - Stratégie québécoise sur la santé des animaux sauvages (PDF 4.46 Mb)