Whirling Disease Research: 
What is whirling disease? 
Whirling disease (Myxobolus cerebralis) is a parasitic infection that affects trout and salmon.  The parasite has a two-host life cycle that involves the fish and an alternate host, the bottom-dwelling tubifex worm.  When an infected fish dies and decays, spores are released and ingested by tubifex worms.  The spores undergo development in the worm's intestine and multiply rapidly.  When released by the worm, the water-borne spores infect susceptible fish by attaching to the fish's body.  The parasite then migrates through the skin to the central nervous system, and ultimately into the cartilage of the fish. 

Why is whirling disease a problem? 

The sporadic devastation of wild trout populations on some of the West's most popular streams and the reduced availability of stocking hatchery-reared trout have caused great concern from fly fishers on remote streams to bait anglers on reservoirs alike.  While biologists have successfully managed around fish diseases for many years, whirling disease presents a far greater challenge than previous diseases because of its impact on both wild and hatchery-reared trout.  Fourteen of the fifteen major drainages in Colorado contain Myxobolus cerebralis, the parasite that causes whirling disease.  Five hundred miles of five major trout streams (Cache La Poudre, Colorado, Gunnison, South Platte and Rio Grande rivers) are showing partial to complete loss of wild rainbow trout recruitment over the past five years. 

Whirling disease research projects 

The Colorado Cooperative Fish and Wildlife Research Unit has been working with the Colorado Division of Wildlife on a variety of research projects focused on identifying the distribution and effects of whirling disease in Colorado. 

  This page is maintained by Diane Schwindt dianes@cnr.colostate.edu 
The content was last updated on April 15, 2004 
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