Detection and New Zealand distribution of myxobolus cerebralis, the cause of whirling disease of salmonids

Abstract

Whirling disease, caused by Myxobolus cerebralis, was diagnosed in rainbow trout (Oncorhynchus mykiss) at Silverstream Fish Hatchery near Christchurch in 1980. As a consequence, a nationwide survey for M. cerebralis in salmonids was conducted by examination of 5307 wild and hatchery fish. In addition, sentinel rainbow trout were used at six locations to test for whirling disease. This survey and other studies revealed M. cerebralis at locations in the Waimakariri, Rakaia, and Rangitata River catchments, and provide the first New Zealand records of M. cerebralis in brook trout (Salvelinus fontinalis), chinook salmon (Oncorhynchus tshawytscha), and sockeye salmon (O. nerka). This paper demonstrates use of sentinel rainbow trout in detecting low-level asymptomatic infection of M. cerebralis in chinook salmon. © The Royal Society of New Zealand 1993.