Spring Viraemia (Vesiculovirus spp.)
Spring viraemia is typically found in carp species, earning it the name Spring Viraemeia of Carp Virus (SVCV). SVCV is a rhabdovirus (family Rhabdoviridae) and is tentatively placed in the genus Vesiculovirus. It is native to Russia and was thought to be brought over by moving fish stock. It infects freshwater species of the family Cyprinidae which includes bass, trout, pike, and carp. This disease is mainly found in farmed carp but has been observed in the wild. The pathogenicity of this virus depends on the infectious strain present in the water body.
SVCV causes significant fish kills, especially in young fish where rates of mortality have been observed as high as 90%. This disease does not always lead to death, but does prompt a weakened immune response. It spreads through parasitic invertebrates such as the carp louse and leech, feces, urine, dead skin mucous, and skin blisters. It is difficult to eradicate this viral disease without the destruction of all aquatic life.
This disease is not harmful to humans through direct contact or ingestion.
One symptom of this disease is lethargy. This can be observed in fish tanks with fish appearing to lie on their sides, usually at the bottom of tanks. In ponds fish congregate where water flow is slowest. Other symptoms include dark skin, bulging eyes, and swelling of the stomach. For more symptoms of SVCV click here (http://www.thefishsite.com/diseaseinfo/1/spring-viraemia-of-carp/).
Biology: The incubation period lasts 7 to 15 days, but some fish will carry the disease without symptoms. It spreads rapidly in water temperatures of 10 to 27 C. Morbidity and mortality rates vary with stress factors, population density, fish species, and water temperatures. SVCV reproduces in the endothelial cells in blood capillaries and cells of the nephron (the functional units of the kidney).
Control and Management:
Identification of SVCV is not based on observations, as other diseases produce similar symptoms. Proper identification requires sophisticated lab testing.
SVCV spreads by moving infected fish from one body of water to another, moving infected water to another body of water, moving unwashed equipment to another body of water, and natural migration and movement of infected fish.
To prevent the spread of SVCV don’t move fish and clean, drain, and dry your boat (http://www.dec.ny.gov/animals/48221.html).
Title photos: Andy Goodwin (nas.ef.usgs.gov). Inspection photo: (ct.gov).
“Name of the Condition: Spring Viremia of Carp (SVC).” Fish Diseases: Spring Viremia of Carp (SVC): Minnesota DNR. Minnesota Department of Natural Resources, n.d. Web. 30 July 2015. <http://www.dnr.state.mn.us/fish_diseases/svc.html>.
Spring Viremia of Carp. Rep. The Center for Food Security and Public Health, Institute for International Cooperation in Animal Biologics, July 2007. Web. 30 July 2015. <http://www.cfsph.iastate.edu/Factsheets/pdfs/spring_viremia_of_carp.pdf>.
“Spring Viraemia of Carp.” Spring Viremia of Carp – The Fish Site. The Fish Site, n.d. Web. 31 July 2015. <http://www.thefishsite.com/diseaseinfo/1/spring-viraemia-of-carp/>.