Viral encephalopathy and retinopathy in freshwater fish farmed in Italy.

Viral encephalopathy and retinopathy (VER), also known as viral nervous necrosis (VNN), is a neuropathological condition affecting more than forty species fish species, mainly in the marine environment. In a few occasions, the disease has also been reported in certain freshwater species, but limited information is available particularly as regard on clinical signs, characterization of causative agents and epidemiological links with the marine environment