Myxobolus cerebralis, a worldwide cause of salmonid whirling disease

Abstract

Salmonid whirling disease was discovered in Europe in 1893 and has since been spread around the world with shipments of cultured and wild fish. The causative agent is the protozoan parasite Myxobolus cerebralis. whose taxonomy and life cycle remain controversial. It causes lesions of salmonid skeletal tissues, particularly in the head. Diagnosis usually is straightforward, but can be complicated by the presence of other Myxobolus species and by other parasites that cause fish to whirl. The pathogen is difficult to eradicate, but its seriousness can be managed if fish are cultured in spore-free source water, in concrete raceways with strong water flows, or in ponds that are regularly disinfected, and if they are constantly monitored for the presence of spores. Fish can carry M. cerebralis spores and still be healthy. Such fish may be suitable for stocking into waters already containing M. cerebralis. and even for human consumption. © by the American Fisheries Society 1990.