Carp Edema Virus

Carp Edema Virus (CEV), of the family Poxviridea, was first described in 1974 in Japan. These are enveloped viruses with double stand DNA, with the largest virions (virus particles) known in vertebrates. So far, three different lineages, causing clinical symptoms in koi and common carp, were identified.

Carp Edema Virus causes Koi Sleepy Disease, which occurs in a temperature range of 15°-25°C. However, clinical symptoms can also be apparent in common carp at significantly lower temperatures. The incubation period is dependent on water temperature. Classical symptoms of an infection with CEV are lethargy and sleepy behaviour, with lying on the bottom. In addition, erosion and haemorrhage of the skin, including edema of deeper tissue layers, can occur, as well as overproduction of mucous on skin and gills. Secondary infections with bacteria, fungi and other viruses pathogenic for Cypriniformes are possible. For the detection of CEV via PCR, a gill biopsy is recommended.

Differential diagnoses for this disease would be infections with Koi Herpes Virus (KHV), Spring Viraemia of Carp (SVC), pollution of the water with organic compounds as well as the infestation with ectoparasites.