Histopathological and electron microscopy studies on sleepy disease of koi Cyprinus carpio koi in Japan

Concentration of carp edema virus (CEV) DNA in koi tissues affected by koi sleepy disease (KSD)

“…CEV has been known to cause 'koi sleepy disease' (KSD) in ornamental carp varieties (koi) in Japan since the 1970s. For a long time, the occurrence of this disease appeared to be limited to Japan (Oyamatsu et al 1997a, Miyazaki et al 2005. However, the situation changed in 2013 when the first report of koi affected by KSD was published based on samples collected in the UK (Way & Stone 2013).…”

“…A treatment regime using salt baths for a prolonged period of time limited losses for Japanese koi farmers (Miyazaki et al 2005) and led the koi industry to the assumption that KSD could easily be controlled. However, the recent disease outbreaks of clinical KSD in European koi populations indicate the need for further studies on this infection.…”

“…The most common clinical signs of KSD are lethargic behaviour (hence the name 'koi sleepy disease'), swollen gills (Miyazaki et al 2005), enophthalmos and haemorrhages often around the mouth and at the base of the fins (Oyamatsu et al 1997a, Way & Stone 2013. With this set of clinical signs, the disease can easily be mistaken for other diseases, for instance koi herpesvirus disease (KHVD).…”

Comparison of PCR methods for the detection of genetic variants of carp edema virus

“…The virus mainly affects the gills of infected fish, where it causes epithelial lesions and oedema (Miyazaki et al 2005). The disease is associated with lethargic behaviour, with affected individuals cha rac teristically lying at the bottom of the tank.…”

“…Several electron microscope images have documented poxvirus-like particles in the infected gill epithelium (Miyazaki et al 2005). However, despite many attempts, the cultivation of CEV in vitro has not been successful employing the fish cell lines presently available (Jung-Schroers et al 2015, Lewisch et al 2015, Swaminathan et al 2016.…”