DAO 126:111-123 (2017)  -  DOI: https://doi.org/10.3354/dao03161

Viral haemorrhagic septicaemia virus (VHSV Id) infections are detected more consistently using syndromic vs. active surveillance

Pia Vennerström1,*, Elina Välimäki1, Tapani Lyytikäinen2, Maria Hautaniemi3, Gabriele Vidgren1, Perttu Koski4, Anna-Maija Virtala

1Veterinary Bacteriology and Pathology Research Unit, Finnish Food Safety Authority, 00790 Helsinki, Finland
2Risk Assessment Research Unit, Finnish Food Safety Authority, 00790 Helsinki, Finland
3Virology Research Unit, Finnish Food Safety Authority, 00790 Helsinki, Finland
4Veterinary Bacteriology and Pathology Research Unit, Finnish Food Safety Authority, 90590 Oulu, Finland
5Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, 00014 University of Helsinki, Finland
*Corresponding author:

ABSTRACT: The eradication of viral haemorrhagic septicaemia virus (VHSV Id) from Finnish brackish-water rainbow trout Oncorhynchus mykiss farms located in the restriction zone in the Province of Åland, Baltic Sea, failed several times in the 2000s. The official surveillance programme was often unable to find VHSV-positive populations, leading to the misbelief in the fish farming industry that virus eradication could be achieved. The ability of 3 other surveillance programmes to detect infected fish populations was compared with the official programme. One programme involved syndromic surveillance based on the observation of clinical disease signs by fish farmers, while 2 programmes comprised active surveillance similar to the official programme, but included increased sampling frequencies and 2 additional tests. The syndromic surveillance concentrated on sending in samples for analysis when any sign of a possible infectious disease at water temperatures below 15°C was noticed. This programme clearly outperformed active surveillance. A real-time reverse transcriptase-polymerase chain reaction method proved to be at least as sensitive as virus isolation in cell culture in detecting acute VHSV infections. An ELISA method was used to test fish serum for antibodies against VHSV. The ELISA method may be a useful tool in VHSV eradication for screening populations during the follow-up period, before declaring an area free of infection.


KEY WORDS: Rainbow trout · Oncorhynchus mykiss · Novirhabdovirus · Rhabdoviridae · Virus eradication · Fish farm · Aquaculture · RT-PCR · ELISA · Finland


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Cite this article as: Vennerström P, Välimäki E, Lyytikäinen T, Hautaniemi M, Vidgren G, Koski P, Virtala AM (2017) Viral haemorrhagic septicaemia virus (VHSV Id) infections are detected more consistently using syndromic vs. active surveillance. Dis Aquat Org 126:111-123. https://doi.org/10.3354/dao03161

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