Viral haermorrhagic septicaemia virus (VHSV) in wild and farmed fish in Norway

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An overview of reduction in the project due to reduction in the budget is provided in the revised project description attached. Viral Haemorrhagic septicaemia virus (VHSV), the causative agent of viral haemorrhagic septicaemia (VHS), is widespread among several fresh water and marine fish species, both farmed and wild. The virulence of different VHSV strains to different fish species varies, and rainbow trout Oncorhynchus mykiss is regarded as one of the most susceptible species. The presence of VHSV in wild fish has been considered as a threat to the salmonid farming industry. The recent outbreak of VHS in sea farmed rainbow trout in Western Norway (Storfjorden) was caused by VHSV of a genotype that has hitherto only been detected in wild marine speci es and has never earlier been associated with outbreak of VHS in farmed salmonids. The proposal suggests an approach to this objective by screening saltwater populations of wild fish species, including salmonids, for VHSV with subsequent genetic characte rization of detected virus. Experimental pathogenicity studies performed on susceptible species and development of a risk-based surveillance system will contribute to the understanding of possible transmission of VHSV from wild to farmed fish and vice ver sa.