Spring Viremia of Carp Virus (SVCV): Global Status of Outbreaks, Diagnosis, Surveillance, and Research

The spring viremia of carp virus (SVCV) is an OIE-listed rhabodovirus historically responsible for losses of cultured fish in Europe. Acute disease is associated with high mortality, especially in common carp Cyprinus carpio during their first spring season when water temperatures are 10-15 degrees C. Mortality has been reported in other cyprinids and in the Wels caff ish Siluris glanis. The disease is characterized by hemorrhages on the skin and bloody mucus in the intestine, clinical signs shared by other diseases including bacterial infections. In 2002, SVCV was detected on a large koi farm in the USA. The USA isolate was 98% identical to isolates associated with koi and goldfish imported from China, but distantly related to European strains. In spring 2002, a major SVCV kill of common carp occurred in Cedar Lake, Wisconsin. This isolate was also of the Asian type, as were subsequent isolates from wild and cultured fish in several states. In the USA, all infected farmed populations were destroyed and no additional isolates have been detected since 2004. One of the most critical aspects of SVCV diagnosis is to differentiate the disease from the koi herpesvirus (KHV). The most obvious difference is that KHV generally occurs in temperatures of 20-28 degrees C while SVCV disease occurs below 18 degrees C and commonly at 10-15 degrees C.