Carp edema virus a rising threat to global carp population

Abstract

Carp edema virus (CEV), a poxvirus from the family Poxviridae, was first detected in 1974 in Japan and has since spread to most parts of the world. CEV is the etiological agent of koi sleepy disease (KSD), which has adverse health effects on both koi and common carp fish species. Equally, KSD leads to detrimental financial distress to carp farmers and further threatens both food security and ecology. The onset and severity of CEV/KSD is influenced by water temperature and handling stress. The prominent clinical sign of KSD in both koi and common carp is lethargy, which is manifested when the water temperature is in the range of 15 – 25 °C and 6 – 9 °C, respectively. Much advancement is needed to curb the spread of CEV. Since the early years of CEV, the immersion of diseased fish into a 0.5% salt-water solution has been shown to be efficacious in treating the clinical signs but ineffective in eradicating the virus in infected fish. Therefore, infected asymptomatic fish become CEV carriers. This is further exacerbated by the limited knowledge of the transmission pathways of CEV. This paper aims to collate the current knowledge on CEV/KSD, to give an insight into the nature and characteristics of CEV.