Abstract

Pancreas disease (PD), caused by the Salmonid alphavirus (SAV), is the most financially significant viral condition currently affecting Norwegian Atlantic salmon aquaculture. Two subtypes of the virus SAV 2 and SAV3, exist and being able to accurately diagnose the presence of the pathogen is of paramount importance. The objective of this project is to design and perform a field evaluation of diagnostic tests commonly used for determination of PD infection status in Norwegian Atlantic salmon aquaculture. Field validation refers to the scientific process of estimating the accuracy of diagnostic tests when used to demonstrate the presence of the infectious agent and clinical disease in a population under field conditions. It is particularly useful in cases, such as for PD, where a "gold standard" is not present [i.e., a diagnostic test identifying all true positives as positives (sensitivity = 1) and all negatives are true negatives (specificity = 1)]. The application of a validated test strengthens the management and surveillance strategy applied to a specific disease situation. A total of three hundred fish (a hundred for each location) will be tested from locations were outbreaks of SAV2 and SAV3 are known to be occurring, as well as from a control location where the pathogen has never been previously detected. Real-time polymerase chain reaction (RT-PCR) and histopathological examinations, the two most common diagnostic methods for PD, will be performed for each collected sample. Serological testing, virus culture and immunohistochemistry as diagnostic tools are also being considered, and we aim to achieve measures of the sensitivity and specificity of the different diagnostic tests using latent class analysis. The results of this study will be of considerable help in planning and evaluating future (but also past) PD surveillance programs and epidemiological studies.

Acknowledgements

The author would like to thank the Norwegian Veterinary Institute and the Norwegian government for the funding and support provided.

References

1.  Beveridge M. 2004. Cage Aquaculture. Blackwell Publishing:1–3.

2.  Bornø G, Lie Linaker M. Fiskhelserapporten 2014. Harstad: Veterinærinstitutet; 2015:5–7.

3.  Heen K, Monahan RL, Utter F. 1993. Salmon Aquaculture. Fishing News Books: 5–6.

4.  Lillehaug A, Santi N, Østvik A. 2015. Practical biosecurity in Atlantic salmon production. Journal of Applied Aquaculture. 27(3):249–262.