Cardiomyopathy syndrome (CMS) has been diagnosed in Norway since 1985. It affects Atlantic salmon and primarily large farmed fish in seawater that are close to harvest. The economic impact is therefore significant. In spite of the serious impact, the caus e(s) is still unknown. Infectious etiology has been claimed but not proved.
Based upon the hypothesis that CMS is infectious, we will do transmission experiments, applying fish tissues from affected fish farms, sampled from different phases of the diseas e development. The first transmission experiments will use tentative infectious materials from a typical end-stage case of CMS and if necessary, followed by an experiment based on the sequentially sampled materials. If CMS is initiated by infection(s) ear ly in the disease development, materials collected prior to the development of characteristic CMS may be decisive for experimental transmission. Such materials will be sampled during a longitudinal study of CMS from sea water transfer in fish farms where yearly outbreaks have been recorded for years.
The lesions described as characteristic for CMS are dominated by a chronic, extensive inflammation that indicates an end stage of a slowly developing chronic progressive heart disease. The preceding stages of the disease development have not been described. Due to lack of such information, the differentiation from diseases with similar heart pathology as PD and HSMI may be difficult or impossible if the diseases are not presented typically as described. The p resent project will provide new knowledge on the sequential pathology of CMS from field cases simultaneously as possibly infectious materials will be sampled sequentially.
The project will be run as a part of a scientific co-operation between Irland, Sco tland and Norway in which longitudinal sequential studies of PD and diseases with similar pathologies have been given priority together with epidemiology (see attached letter).