Impact of Viral Nervous Necrosis (VNN) Disease as a New Threat to Global Fisheries and Aquaculture Development, a Review

Viral Nervous Necrosis (VNN) causes viral encephalopathy and retinopathy (VER), a hazardous and devastating disease of many species of cultured and marine fish worldwide. It caused by betanodaviruses a serious concern especially in the fry and young fish. This virus infects most of the cultured fishes causing severe mortality. Our current review focuses chiefly on recent studies performed on VNN disease. Recent outbreaks have been reported in China, Indonesia, Singapore and India, affecting the mariculture and aquaculture industry. It also decreased dramatically Mullet stocks in the Caspian Sea. The four main genotypes of VNN were found in all continentals’ except South America. The economic loss due to the virus is mainly due to mortality and spread of infection both vertically and horizontally. Our investigation in recent years suggest that more research and epidemiological surveys should be conducted, especially in critical areas were mariculture farms are planned to be established. Therefore, finding new rapid diagnosis tools, Monitoring and Surveillance program, and effective vaccines, Control, Prevention and Eradication in the comprehensive program should be considered globally.