What is it?
Spring viraemia of carp (SVC) is an infectious viral disease of carp (Cyprinus carpio) and other cyprinid fish species. The common carp is the principal host, but clinical disease has also been reported to occur in koi carp, grass carp, silver carp, crucian carp, goldfish, tench and sheatfish. SVC is present in a number of European countries which experience low water temperatures, including the UK, and it has recently been reported in the USA.
Where and When Might it Occur?
High mortality can occur in all age groups of fish at water temperatures between 10 and 17°C, especially in spring. However, fry can be affected at temperatures as high as 23°C.
SVC virus multiplies in endothelial cells in blood capillaries, haematopoietic tissue and cells of the nephron. Clinical characteristics of affected fish are impairment to the salt water balance, which occurs in association with oedema and haemorrhage.
The causative agent of SVC is a rhabdovirus. It can be isolated in cell culture and identification is achieved by ELISA, immunofluorescence and virus neutralisation test.
The virus can be spread by water and by movement of live infected fish. Controls are based on prevention of movement of fish and equipment from infected farms to uninfected locations, and by appropriate hygiene measures.
SVC is notifiable within Great Britain and is a listed disease under Schedule 1 of the Aquatic Animal Health (Scotland) Regulations 2009.
Fish which survive outbreaks of SVC can develop strong protective immunity against the disease. Currently there are no licensed vaccines against SVC.