Whirling Disease (Myxobolus cerebralis)

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Whirling Disease(Myxobolus cerebralis)
Eric Stock Bio. 4800
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Outline

• History
• Distribution
• Species Infected
• Life Cycle
• Breeding Resistance

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Where did WD come from?

• European Origin
• First recorded in Germany (1903)
• Introduced to the United States (1950s)
• Now Worldwide distribution

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World Distribution
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Canada???

• Currently no literature reporting WD in Canada
• Approaching Albertan and British Columbian
  Borders

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Species Susceptibility

• 0 Resistant
• 1 Partial Resistance
• 2 Susceptible
• 3 Highly Susceptible
• S Susceptibility unclear

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Trout in Alberta

• Non-native Species

• Native to Alberta

• Bull Trout
• Cutthroat Trout
• Lake Trout
• Rainbow Trout

• Brook Trout (Eastern Canada)
• 1903
• Brown Trout (Europe/Asia)
• 1924
• Golden Trout (California)
• 1959

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Life Cycle

• Primary Host
• Trout/Salmon
• Secondary Host
• Tubifex Worms
• TAM infective stage
• Spores can survive 20-30 years in mud
• Juveniles less than 5 months
• most susceptible

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1. Myxobolus cerebralis spore
2. Tubifex Worms
3. TAMs (Triactinomyxon)
4. Infected Trout
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Parasite Transfer
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Bird/Mammal Transfer?

• Myxospores have been found in digestive tract of
  piscivorous birds
• Avian vector is still unclear
• Myxobolus cerebralis is very specific
• Trout/salmon only
• Fish eating mammals cant be infected by the
  parasite
• Eating fish will not infect YOU with WD

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Breeding Resistance?

• Microarray analysis examined expression changes
  in resistant and susceptible strains of rainbow
  trout after exposure to M. cerebralis
• Hatchery rainbow trout from Germany (Hofer
  strain)
• Acquired a degree of resistance to whirling
  disease
• Higher than any domestic rainbow strains
• Comparable to that of brown trout
• Native to Europe (asymptomatic) to WD
• Susceptible rainbow trout (US) Trout Lodge

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Results

• For both the resistant Hofer and susceptible
  Trout Lodge rainbow trout strains
• Response to infection linked with the interferon
  system
• Metallothionein B was differentially expressed
  between the resistant and susceptible strains
• A good candidate for future whirling disease
  resistance studies

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Conclusion

• The identified genes have allowed insight into
  trouts immune response and resistance to
  whirling disease infection.
• Additional studies crossed the resistant Hofer
  strain with a susceptible CRR strain (Colorado
  River rainbow trout )
• Resistance to whirling disease was inherited by
  offspring
• Management to re-establish trout in areas
  affected by WD

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References

• Baerwald, M.R, Welsh, A.B, Hedrick, R.P, May. B.
  2008. Discovery of genes implicated in whirling
  disease infection and resistance in rainbow
  trout using genome-wide expression profiling.
  BMC Genomics. 9 1471- 1482
• Gilbert, M.A, Granath, W.O. 2003. Whirling
  Disease of Salmonid Fish Life Cycle, Biology,
  and Disease. The Journal of Parasitology. 89
  658-667
• http//berryns.wordpress.com/2010/01/27/whirling-d
  isease/
• http//whirlingdisease.montana.edu/default.asp
• http//wildlife.state.co.us/Research/Aquatic/Whirl
  ingDisease/WDResistantTroutBroodstock.htm
• http//www.srd.alberta.ca/BiodiversityStewardship/
  WildSpecies/Fish/Default.aspx
• http//www.thebowriver.com/whirling_disease_tu.htm
  
• http//www.tu.org/whirling-disease

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Questions?

• Be Nice!