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First Incidence of Koi Sleepy Disease in Austria

First Incidence of Koi Sleepy Disease in Austria

Article by: Nur Hidayahanum Hamid

Source: University of Veterinary Medicine, Vienna

Carp edema virus (CEV), also known as koi sleepy disease (KSD), is an infectious disease first reported in Japan in the 1970s. Infected fish show extreme apathy and exhibit symptoms like sunken eyes, dermatological changes, and swollen gills. Serious cases affect gill tissue, impairing oxygen delivery. The disease has spread across Europe, with cases reported in Germany, France, the Netherlands, and England, affecting koi and common carp. In Austria, diagnostic work by Eva Lewisch and colleagues identified the disease using molecular detection.

The pathogen is believed to have originated in Asia. While the exact type is unclear, electron microscopy suggests it may be a smallpox-like virus. Genetic analysis indicates that KSD has been in Austria since at least 2010, with increased mortality observed in spring, likely due to the virus.

Environmental factors like water temperature and stress trigger outbreaks. European carp fall ill at lower temperatures than koi in Asia, suggesting the virus may have mutated to adapt to European conditions. The global koi trade poses a significant risk for spreading viral infections, including the koi herpes virus (KHV), which has caused substantial economic damage worldwide. A workshop on KSD/CEV will be held at the European Association of Fish Pathologists (EAFP) conference.

Picture 1: Necrotic gill tissue of a diseased koi. Credit: Eva Lewisch/Vetmeduni Vienna

Picture 2: Sunken eyes, dull colouration, and swollen/red gills can be symptoms. Photo: Deborah B. Pouder, University of Florida

Picture 3: Typical symptoms of the disease include dermatological changes. Credit: Courtesy of Bartolomeo Gorgoglione/Vetmeduni Vienna

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