If they survive, fish may develop head deformities or twisted spines. Fish biologists believe there are other harmful effects, such as making fish more susceptible to predation and environmental disturbances, as well as impairing their ability to feed and reproduce. The parasite exhibits a complex life cycle. One stage is hosted by small aquatic worms which are common to most waters. Host worms release the more fragile parasitic stage that must infect a trout within a few days or die.
Infected trout develop very persistent spores which can survive in moist places for years.
When an infected fish dies, these spores are released into the environment. The spores can be transferred to other waters on muddy boots or other fishing equipment. Rainbow trout are the most susceptible of Utah's game fish, followed by kokanee salmon, golden, cutthroat, brook, brown trout and splake. Whitefish and grayling can be infected as well. There is currently no known treatment or cure for fish infected with the parasite.