Scientists believe there are other harmful effects such as making fish more susceptible to predation, less able to feed, to survive environmental disturbances or to reproduce. Recently, fisheries researchers have initiated long-term Whirling Disease impact studies, but no definitive conclusions have been made. However, population collapses in famous rainbow trout rivers such as the Madison and Colorado have caused experts to reassess the parasite's impact. The parasite goes through a complex life cycle that includes living in tiny aquatic worms which are found in most waters. These host worms, which become infected, release a fragile parasitic stage that must infect a trout within a few days or perish.
Infected trout develop very persistent spores which can survive in moist environments for years.
When an infected fish dies and decomposes, the spores are released into the environment and can survive transit through a predator's digestive tract or could be transferred on muddy boots or other equipment. Among species found in Utah, rainbow trout are the most susceptible, followed by kokanee salmon, golden, cutthroat, brook, brown trout and splake. Recent discoveries suggest whitefish and grayling may be infected as well. Lake trout may be immune and other game fish species such as bass, bluegill, perch or walleye do not get whirling disease. Please Note That The Parasite DOES NOT Infect Human Beings.