Spring Viremia_ United States

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June 17, 2004

Impact Worksheet


Spring Viremia of Carp (SVC) was confirmed in Snohomish County, Washington on June 9, 2004 in koi in a backyard pond. SVC is a viral disease mainly affecting several species of cyprinid fish.

There were a total of 115 facilities producing koi and 65 facilities producing ornamental goldfish in the US in 1997. The combined sales value for koi and goldfish from these facilities are estimated to be $10.7 million. Washington State had 2 facilities that produced koi and ornamental goldfish in 1997.

In response to the SVC finding in Washington, the fish remaining in the pond will be culled and tested for SVC. A traceback from the pet store where the fish were purchased is underway.

How extensive is the situation?

Map Koi infected with SVC were identified in one backyard pond in Snohomish County, Washington. The diagnosis was confirmed at the National Veterinary Services Laboratory (NVSL) on June 9, 2004. Cell culture, PCR and sequencing were performed. The pond water does not have any connection to the natural waterways, and no fish from the pond were moved off the premises after purchase from a pet store, so no exposure to other ornamental or wild fish is suspected. Eleven koi were placed in a backyard pond this spring; about a month later, 5 of the koi died. A koi was submitted for testing to the Washington Animal Disease Diagnostic Lab on May 5, 2004. The pond also contained approximately 100 goldfish. None of the goldfish appeared to be affected. The remaining fish in the pond will be culled and sent to NVSL for testing. A traceback from the pet store is being performed and any traces linked to the fish from the affected premises may be tested.

What is SVC and where does it occur?

SVC is a viral disease of fish; it primarily affects common carp. It is a systemic, acute and highly contagious disease. SVC is caused by Rhabdovirus carpio , which is a typical bullet shaped virion. SVC typically occurs when water temperatures are less than 18 ° C and is most common in the spring. At 20-22 ° C, infection occurs but clinical disease does not develop, as the fish is able mount an immune response at this temperature. When clinical disease is present, mortality ranges from 30-90%, and is dependent upon fish age, water temperature, fish species and living conditions. Clinical signs include congregation in slow moving water, decreased respiration and decreased response to stimuli. Other, nonspecific signs such as skin darkening, swollen abdomen, exophthalmia, pale gills and protruding vent may also be present. The gill is the most common portal of entry. SVC is transmitted horizontally through the water and by blood sucking parasites such as the carp louse ( Argulus foliaceus ) and leech ( Pisciola geometra ). Successful treatment of infected fish has not been demonstrated. There is no approved vaccine for SVC in the US . Control measures include iodophore disinfection of eggs and periodic chemical and physical disinfection of ponds and equipment. Minimizing stress and overcrowding and sanitary disposal of dead fish are also recommended. Raising fish at a water temperature of 19-20 ° C has been suggested.

SVC has previously been reported in Europe , the Middle East and Asia . More recently, it has been reported in North and South America . In the US , a koi farm in North Carolina experienced an SVC outbreak in 2002, and the virus has emerged in wild common carp populations in Wisconsin and Illinois . SCV is an OIE List B reportable disease.

Sources: APHIS VS Tech Notes, CEI Impact Worksheets, Federal Register/ Vol. 69, No. 95, OIE

What species are susceptible to the SVC virus and are they present in Washington State ?

Most of the fish species that are susceptible to the SVC virus belong to the Family Cyprinidae. While the common carp ( Cyprinus carpio ), including the Koi variety, are the primary Cyprinidae species affected, other Cyprinidae species and a few species not in the Family Cyprinidae are also susceptible to the SVC virus.

In addition to the common carp, species that have been found to be susceptible to the SVC virus under natural conditions include the grass carp ( Ctenopharyngodon idellus ), silver carp ( Hypophthalmichthys molotrix ), bighead carp ( Aristichthys nobilis ), crucian carp ( Carassius carassius ), goldfish ( Carassius auratus ), tench ( Tinca tinca ), and sheatfish ( Silurus glanis ). Under experimental conditions, golden shiners ( Notemigonus crysoleucas ), roach ( Rutilis rutilis ), pike ( Esox lucius ), guppy ( Lebistes reticulates), pumpkinseed ( Lepomis gibbosus ), and zebra danios ( Brachynadio rerio ) were also found to be susceptible to the SVC virus.

There are many additional species in the Family Cyprinidae, the principal SVC virus hosts, and their susceptibility to the SVC virus is not presently known.

None of the species known to be susceptible to the SVC virus are native to Washington State waterways, however several species that could potentially become infected were introduced into Washington State waters and have since become established. These species include the common carp, grass carp, goldfish, tench, golden shiner, pumpkinseed and northern pike.

Sources: Spring Viremia of Carp, APHIS Technical Note, April 2003 ; Washington State Aquatic Nuisance Species Management Plan, Washington Department of Fish and Wildlife, September 2001

What is the size of the affected cyprinid industry in the US and in Washington State ?

The most recent data on fish sales by species and state are available on the National Agricultural Statistics Services (NASS) 1997 Census of Aquaculture. These data show that there were a total of 115 facilities producing koi and 65 facilities producing ornamental goldfish in the US in 1997 (Table 1). The combined sales value for koi and goldfish from these facilities is estimated to be $10.7 million. Washington State had 2 facilities that produced koi and ornamental goldfish in 1997. Due to producer confidentiality requirements, the sales value of koi and goldfish production for Washington State is not available.

In 1997 there were 34 facilities in the US that produced feeder goldfish (bait) and 39 facilities that produced carp as food fish. The value of production for these categories of cyprinids was $9.3 million and $1.3 million, respectively. There were no facilities producing feeder goldfish or food carp in Washington State.

Table 1: Number of facilities and value of sales for affected fish in the US and Washington State , 1997

Type of fish

Number of facilities

Value of sales ($ million)

US total


US total







Ornamental goldfish





Feeder goldfish





Food carp





- = withheld to avoid disclosing data for individual farms

Source: USDA, NASS, 1997 Census of Aquaculture

What is the USA ’s place in the international market for affected fish?

The US produced 10,869 metric tons of carps, barbels, and other cyprinids in 2001, accounting for less than 0.1% of world production.

Source: United Nations FAO

What are the U.S. exports of affected fish?

The US exported live carp worth $1.7 million in 2003 and $651,000 during the first four months of 2004. These fish were exported almost exclusively to Canada , with only minor sales values to Mexico and Trinidad and Tobago in 2003. None of the live carp that were exported in 2004 or 2003 originated in Washington State .

Table 2: US exports of live carp, 2003 and January - April 2004


$ value (million)


2004 (Jan-Apr)

Live carp



Source: World Trade Atlas

CEI’s plans for follow up:

CEI will continue to monitor the situation but has no plans at this time to issue additional reports.

If you seek more information or wish to comment on this worksheet, please contact Cynthia Johnson at 970-494-7332 or Wolf Weber at 970-494-7222.

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