Myxobolus cerebralis Factsheet
Hofer, 1903
(.pdf version of this document)
Scientific Name: Myxobolus cerebralis
Common Name: myxosporean parasite, salmonid whirling disease
Taxonomy: available through ITIS
Identification: M. cerebralis occurs in two stages. In one stage it has a myxospore form that contains a polar filament for injection of the cell contents (containing a binucleate infective germ cell) into the epithelial cells of the intestine of a host oligochaete (Tubifex tubifex). In the other stage it has a triactinomyxon (TAM) spore form that also is equipped with a polar filament for attachment to the epithelium of a salmonid host. In general, spores are oval, frequently asymmetrical, and exhibit 5 or 6 irregular coils in the polar filament (Mills et al. 1993; Gilbert and Granath 2003; Lom and Hoffman 2003; Kallert et al. 2005).
In infected salmonids, the disease caused by M. cerebralis can result in whirling behavior or tail-chasing; damage to the central nervous system and organs of equilibrium; lesions in the skull, gills, and vertebrae; and sometimes mortality (Mills et al. 1993; Crawford 2001; Gilbert and Granath 2003; Krueger et al. 2006).
Size: M. cerebralis spores are around 7.5–10 µm in length (Lom and Hoffman 2003; Krueger et al. 2006).
Native Range: Unknown. However, M. cerebralis is a common European parasite of brown trout (Salmo trutta) and could have evolved with this host species, which is generally asymptomatic to infection. This association could have originated in Central Europe (Crawford 2001; Gilbert and Granath 2003; Krueger et al. 2006).
Nonindegenous Occurences: M. cerebralis was recorded for the first time in 1968 in an Ohio aquaculture operation within the Lake Erie drainage. It may have been present in the Great Lakes system since the 1950s. It has been recorded primarily from aquaculture facilities, or waters in the immediate vicinity of such operations, in the Lakes Erie, Ontario, and Michigan drainages, but also in the wild in tributaries of Lakes Huron and Superior (Mills et al. 1993; Whirling Disease Initiative 1997-1998; Crawford 2001; Great Lakes Fishery Commission 2001).
Means of Introduction: M. cerebralis was very likely introduced with nonindigenous salmonids that were stocked in the Great Lakes drainage system (Mills et al. 1993). It could have arrived with transfers of rainbow trout (Oncorhynchus mykiss) from Europe back to North America before 1956 (Crawford 2001).
Status: Established within the Great Lakes basin, although most occurrences have been at hatcheries and prevention and control measures have increased.
Ecology: M. cerebralis is the causal agent of salmonid whirling disease. Rainbow trout (Oncorhynchus mykiss) is particularly susceptible to this pathogen. The following species are susceptible but generally considered less so than rainbow trout: sockeye salmon (Oncorhynchus nerka), golden trout (O. aguabonita), cutthroat trout (O. clarki), brook trout (S. fontinalis), Atlantic salmon (Salmo salar), bull trout (Salvelinus confluentus), and chinook salmon (Oncorhynchus tshawytscha). Brown trout (S. trutta) is susceptible but infections are usually asymptomatic. Lake trout (Salvelinus namaycush) is not susceptible to infection (Bartholomew et al. 2003; Gilbert and Granath 2003; Sollid et al. 2003; Blazer et al. 2004; Krueger et al. 2006).
M. cerebralis has an obligate host: the oligochaete T. tubifex. Different strains of this species are susceptible to infection by M. cerebralis while others are not. TAMs develop in T. tubifex via asexual and sexual reproduction, requiring a total of 3 months in the region between the epithelial cells of the oligochaete’s intestine to reach maturity. They are then released into the water column and must infect their salmonid hosts within around 1–15 days. Both mechanical and chemical mucus-derived signals trigger their discharge. Upon discharge at the epidermis of the fish, the sporoplasm, containing a group of infective germ cells, is injected into the host. The germ cells then move into the nervous system, reproducing and eventually moving to the cartilage. Development in the fish host is asexual and occurs in inter- and intra-cellular spaces, requiring around 3 months for myxospore formation. Myxospores can be passed to another fish at this point if the first host is ingested by a predator. If this is the case, they will pass out in the second host’s feces to settle in the sediments. Otherwise, the spores remain in the first fish host’s tissue upon mortality and eventually end up in the sediments as the carcass decays. Myxospores can survive temperatures of -20°C. They are then taken up from the sediments by feeding T. tubifex and the lifecycle begins again (El-Matbouli et al. 1999; Gilbert and Granath 2003; Kallert et al. 2005; Elwell et al. 2006; Kaeser et al. 2006; Krueger et al. 2006).
The severity of infection in salmonids may be correlated with water temperature and water conductivity. Temperatures from 5–17°C are best for TAM production while temperatures of ›20°C are inhibitive. Depending on the strain of T. tubifex hosting TAMs, ideal temperature for development can vary. Finer sediments also may hold spores better than more coarse sediments. Moreover, finer sediments and slower moving waters are ideal habitat for T. tubifex and thus may favor higher infection rates of M. cerebralis in salmonids. Finally, larger and older rainbow trout (at least 40 mm in length and at least 9 weeks old) have increased resistance to exposure to this disease (Blazer et al. 2003; Burckhardt and Hubert 2005; Ryce et al. 2005; Kerans et al. 2005; Krueger et al. 2006).
Impact of Introduction:
A) Realised: Salmonid whirling disease has mostly been problematic in hatcheries within the Great Lakes system, where stock can be seriously affected. Managers have observed that using concrete in aquaculture facilities can reduce the abundance of T. tubifex and thus limit the ability of M. cerebralis to reproduce. However, M. cerebralis has occurred in some areas or tributaries in the Great Lakes drainage system at different times, and since it can parasitize all exotic salmonids present (O. tshawytscha, O. kisutch, O. nerka, O. mykiss, and S. trutta), its persistence is being facilitated by the presence of these exotic fishes (Mills et al. 1993; Ricciardi 2001).
B) Potential: In Yellowstone Lake, Wyoming, M. cerebralis is contributing to a decline in a native salmonid, the Yellowstone cutthroat trout (O. clarki bouvierii) (Koel et al. 2006). Wild rainbow trout populations in Montana and Colorado (but neither in California nor in Oregon where infections have also occurred) have declined due to this parasite (Krueger et al. 2006). Impacts on rainbow trout have been documented in over 22 U.S. states and this disease has been reported from 26 different countries (Gilbert and Granath 2003; Kallert et al. 2005).
Remarks: Myxobolus cerebralis is synonymous with Myxosoma cerebralis
Voucher Specimens:
References:
Bartholomew, J. L., H. V. Lorz, S. A. Sollid, and D. G. Stevens. 2003. Susceptibility of juvenile and yearling bull trout to Myxobolus cerebralis and effects of sustained parasite challenges. Journal of Aquatic Health 15(3):248-255.
Blazer, V. S., C. L. Densmore, W. B Schill, D. D. Cartwright, and S. J. Page. 2004. Comparative susceptibility of Atlantic salmon, lake trout and rainbow trout to Myxobolus cerebralis in controlled laboratory exposure. Diseases of Aquatic Organisms 58(1):27-34.
Blazer, V. S., T. B. Waldrop, W. B. Schill, C. L. Densmore, and D. Smith. 2003. Effects of water temperature and substrate type on spore production and release in eastern Tubifex tubifex worms infected with Myxobolus cerebralis. Journal of Parasitology 89(1):21-26.
Burckhardt, J. C. and W. A. Hubert. 2005. Evidence of relationships between Tubifex habitat and Myxobolus cerebralis across a mountain watershed. Intermountain Journal of Sciences 11(3-4):45-57.
Crawford, S. S. 2001. Salmonine Introductions to the Laurentian Great Lakes: An Historical Review and Evaluation of Ecological Effects. Canadian Publication of Fisheries and Aquatic Sciences 132. 205 pp.
El-Matbouli, M., T. S. McDowell, D. B. Antonio, K. B. Andree, and R. P. Hedrick. 1999. Effect of water temperature on the development, release and survival of the triactinomyxon stage of Myxobolus cerebralis in its oligochaete host. International Journal of Parasitology 29(4):627-641.
Elwell, L. C., B. L. Kerans, C. Rasmussen, and J. R. Winton. 2006. Interactions among two strains of Tubifex tubifex (Oligochaeta: Tubificidae) and Myxobolus cerebralis (Myxozoa). Diseases of Aquatic Organisms 68(2):131-139.
Gilbert, M. A. and W. O. Granath Jr. 2003. Whirling disease of salmonid fish: life cycle, biology, and disease. Journal of Parasitology 89(4):658-667.
Great Lakes Fishery Commission. 2001. Minutes of the Lake Superior Technical Committee Summer Meeting. August 1 – 2, 2001. Grand Marais, Michigan. 16 pp.
Kaeser, A. J., C. Rasmussen, and W. E. Sharpe. 2006. An examination of environmental factors associated with Myxobolus cerebralis infections of wild trout in Pennsylvania. Journal of Aquatic Animal Health 18(2):90-100.
Kallert, D. M., M. El-Matbouli, and W. Haas. 2005. Polar filament discharge of Myxobolus cerebralis actinospores is triggered by combined non-specific mechanical and chemical cues. Parasitology 131:609-616.
Kerans, B. L., R. I. Stevens, and J. C. Lemmon. 2005. Water temperature affects a host-parasite interaction: Tubifex tubifex and Myxobolus cerebralis. Journal of Aquatic Animals Health 17:216-221.
Koel, T. M., D. L. Mahony, K. L. Kinnan, C. Rasmussen, C. J. Hudson, S. Murcia, and B. L. Kerans. 2006. Myxobolus cerebralis in native cutthroat trout of the Yellowstone lake ecosystem. Journal of Aquatic Animal Health 18(3):157-175.
Krueger, R. C., B. L. Kerans, E. R. Vincent, and C. Rasmussen. 2006. Risk of Myxobolus cerebralis infection to rainbow trout in the Madison River, Montana, USA. Ecological Applications 16(2):770-783.
Lom, J. and G. L. Hoffman. 2003. Morphology of the spores of Myxosoma cerebralis (Hofer, 1903) and M. cartilaginis (Hoffman, Putz, and Dunbar, 1965). Journal of Parasitology 89(4):653-657.
Mills, E. L., J. H. Leach, J. T. Carlton and C. L. Secor. 1993. Exotic Species in the Great Lakes: A History of Biotic Crises and Anthropogenic Introductions. Journal of Great Lakes Research 19(1):1-54.
Ricciardi, A. 2001. Facilitative interactions among aquatic invaders: is an “invasional meltdown” occurring in the Great Lakes? Canadian Journal of Fisheries and Aquatic Sciences 58:2513-2525.
Ryce, E. K. N., A. V. Zale, E. MacConnell, and M. Nelson. 2005. Effects of fish age versus size on the development of whirling disease in rainbow trout. Diseases of Aquatic Organisms 63(1):69-76.
Sollid, S. A., H. V. Lorz, D. G. Stevens, and J. L. Bartholomew. 2003. Age-dependent susceptibility of Chinook salmon to Myxobolus cerebralis and effects of sustained parasite challenges. Journal of Aquatic Animal Health 15(2):136-146.
Whirling Disease Initiative. 1997 1998. Research Findings 1997 – 1998, National Partnership on the management of wild and native cold water fisheries, Montana University System Water Center, MSU-Bozeman. 6 pp.
Other Resources
Authors: Rebekah M. Kipp
Revision Date: Apr. 23, 2007
Citation for this Information: Rebekah M. Kipp. 2007. GLANSIS.
Group: Category not available – parasite
Lake(s): All Great Lakes Drainages
Genus: Myxobolus (synonymous with Myxosoma)
Species: cerebralis
Common Name: myxosporean parasite, salmonid whirling disease
Status: Established (although prevention and control measures at hatcheries have increased).
Freshwater/Marine: Freshwater
Pathway: Stocking (of exotic salmonid hosts)
Exotic/Transplant: Unknown
For the current distribution map and collection information, please use the database at: http://www.glerl.noaa.gov/res/Programs/ncrais/nas_database.html