The presence of BKD in the north of Germany has been suspected for years but no convincing evidence has until now been obtained.
In late 1984, rainbow trout fingerlings were sent to our laboratories for health inspection. The diseased fish came from a trout farm in the west of Germany (Eifel). They showed unilateral exophthalmus, slightly swollen abdomens and greyish gills. Some fish had lost their eyes. On dissection, the most marked signs were swollen kidneys with grey patches.
Laboratory examinations excluded the presence of virus or parasites but positively demonstrated the causative agent of BKD, Renibacterium salmoninarum (Lehmann and Mock, 1985) by means of the immunofluorescence method.
A second case of BKD occurred even further north, in lower Saxony, in April 1985. Again, the agent could be demonstrated and in this case grown on specific agar. Clinical symptoms in this case were far less pronounced as compared to the typical ones described in the literature.
These findings show BKD for the first time in the west and north of Germany far north of Bavaria and demonstrates that the disease is further spreading to areas which were previously known to be free of BKD.