Spring viremia of carp (SVC) is a deadly and contagious viral disease that affects farmed carp and related species, causing significant economic losses. “Infectious dropsy of carps” was the term given to the disease. The disease spring viremia of carp affects freshwater fish. A virus causes the disease, which can be harmful to fish.
It is especially harmful to young fish, with up to 90% mortality rates. The virus can spread through fomites and parasitic invertebrates, and eradication may require destroying all aquatic life in the affected pond. SVC has been around for over 50 years and kills 10-15% of one-year-old carp yearly.
Spring Viremia Management in Carp Fish
Causative Agents of Spring Viremia in Carp Fish
Spring viremia of carp (SVC) is a viral disease that affects common carp and other members of the Cyprinidae family. The disease is caused by the spring viremia of carp virus (SVCV), also known as Rhabdovirus carpio, which is a member of the Rhabdoviridae family and closely related to pike fry rhabdovirus.
The virus is spread through water and can infect fish of all sizes. SVCV strains vary in their pathogenicity and can be divided into four genetic groups. The disease is highly contagious and can cause significant economic losses in farmed carp and related species. SVCV is difficult to eradicate, and once it is established in a pond, elimination may require destroying all aquatic life.
Spread and Transmission of Spring Viremia in Carp Fish(SVC)
- Sick and healthy fish can carry spring viremia of carp virus (SVCV). It can be passed through feces, urine, gill and skin mucus, blister fluid, and swollen scale pockets.
- The disease spreads through direct contact or water, and the gills are the most common entry point. SVCV can also be spread by vectors like the carp louse and the leech, and it can live in water and mud for a few weeks. Birds that eat fish could also spread the disease.
- Eggs are not a major way that diseases spread from one person to another. Infected fish exhibit slow swimming, slow breathing, and a sluggish response to stimuli.
- The virus is transmitted through the water column, and infected fish can shed the virus for several weeks. Effective management plans should include ways to stop the spread of fomite and vectors.
- Various invertebrate vectors, including blood-sucking parasites like the leech Piscicola geometra and the carp louse Argulus foliaceus, can spread Spring Viremia of Carp (SVC).
- These parasites can become infected by feeding on the blood of infected fish and can transmit the virus to healthy fish.
Symptoms of Spring Viremia in Carp Fish(SVC)
- Experimental infections show incubation periods of 7 to 15 days.
- Fish up to one year old are most commonly affected, but older fish can also become ill.
- Clinical signs are nonspecific and can be carried with or without symptoms.
- Common disease symptoms in carp include a swollen abdomen, bulging eyes, inflammation or swelling in the vent, mucoid feces sticking to the body, small blood spots, darkened bodies, and pale gills.
- When sick, fish tend to gather at the water’s edge or the entrance to the pond. They swim and breathe slowly and don’t react quickly to anything.
- Late stages of the disease show loss of equilibrium with resting and leaning.
- Concurrent bacterial or parasitic infections can influence symptoms.
Diagnosis of Spring Viremia in Carp Fish(SVC)
- Diagnosis of SVC involves clinical suspicion based on systemic infection signs and increased mortality rates in cyprinid fish with water temperatures below 20°C.
- The clinical signs and lesions are not diagnostic independently; they nee