SLEEPING DISEASE AND PANCREAS DISEASE - COMPARATIVE HISTOPATHOLOGY AND ACQUIRED CROSS-PROTECTION

Sleeping disease (SD), a disease of freshwater-reared rainbow trout, O ncorhynchus mykiss (Walbaum), was histologically compared to pancreas disease (PD), a disease of seawater-reared Atlantic salmon, Salmo sala r L. Some weeks after injection of kidney homogenates from SD- or PD-a ffected fish in rainbow trout, the fish successively developed pancrea tic, heart and muscular lesions in both populations, although the SD-i njected population was the most affected. An acquired protection was o bserved against PD and SD after an initial injection with PD- or SD-in fective material. This acquired cross-protection and the similar histo pathologies in PD and SD suggest the two diseases could be caused by a similar or identical agent.