Tuesday, May 22, 2018

22/05/2018: Pancreas disease in farmed salmon

by MSD Animal Health, UK

MSD Animal Health has undertaken a comprehensive survey of pancreas disease in farmed salmon in Scotland.

One of the key findings of the Scottish Pancreas Disease (PD) Mapping Project is that blanket vaccination appears to have resulted in a significant reduction in positive results.

The results of the project also suggest that herd immunity and improved husbandry practices may also be proving effective as pancreas disease has now fallen down the list of most prevalent diseases found in farmed salmon, however remains a continued risk.

The year-long study by MSD Animal Health, working in collaboration with producers of farmed salmon in Scotland, undertook survey work across 96 sites in Scotland, covering the Western Isles, Orkney and Shetland (the Northern Isles) and along the West coast.

The survey covered both vaccinated and unvaccinated populations to evaluate vaccine efficacy comparing comprehensive historical data collected since 2008 and a similar mapping project completed in 2015 with the recent findings.

For the PD Mapping Project 2018 the methodology used was similar to that of the 2015 project, which was to assess the prevalence of Salmonid alphavirus (SAV) and neutralizing antibodies, which indicated a challenge has been present. Where positive SAV was identified, the virus was subtyped to determine which of the six subtypes of SAV were found. This has enabled the mapping project team to provide the most comprehensive view yet of the geographical distribution of SAV subtypes.

Results of samples can highlight the following:
1. Negative virus and antibody: No exposure to the site to PD at that precise moment in time;
2. Positive virus: Active, circulating viral infection;
3. Positive antibody and positive virus: Mid to late stage infection;
4. Positive antibody only: Previous infection.

Serology samples were the predominant diagnostic method used during the survey. Samples were taken at key periods during the production cycle when the SAV infection pressure is likely to be most present.

Read the full article, HERE.

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