scholarly journals Effect of cadmium on the susceptibility of Tubifex tubifex to Myxobolus cerebralis (Myxozoa), the causative agent of whirling disease

2010 ◽  
Vol 89 ◽  
pp. 63-70 ◽  
Author(s):  
S Shirakashi ◽  
M El-Matbouli
Keyword(s):  
Causative Agent ◽  
Tubifex Tubifex ◽  
Whirling Disease ◽  
Myxobolus Cerebralis

Myxobolus cerebralis (Myxozoa), the causative agent of whirling disease, reduces fecundity and feeding activity of Tubifex tubifex (Oligochaeta)

Parasitology ◽  
2009 ◽  
Vol 136 (6) ◽  
pp. 603-613 ◽  
Author(s):  
S. SHIRAKASHI ◽  
M. EL-MATBOULI
Keyword(s):  
Causative Agent ◽  
Feeding Activity ◽  
Ecological Impacts ◽  
Tubifex Tubifex ◽  
Infection Prevalence ◽  
Limited Information ◽  
Whirling Disease ◽  
Myxobolus Cerebralis ◽  
Cocoon Production ◽  
Spore Release

SUMMARYMyxobolus cerebralis is the causative agent of whirling disease that has significant economical and ecological impacts on trout populations. Although intensive studies have been conducted to understand its effects on and interactions with its fish host, only limited information is available about how and to what extent M. cerebralis affects its oligochaete host, Tubifex tubifex. We investigated the effects of M. cerebralis on survival, growth, reproduction, and feeding activity of T. tubifex. Mature, immature and juvenile worms were exposed to myxospores and their infection prevalence, mortality, sexual development, reproduction and spore production were compared with unexposed worms. The parasite affected neither survival nor growth but inhibited clitellar development and reduced cocoon production by over 80%. Numbers of actinospores released from mature worms were nearly 9-fold higher than that of immature worms. When non-clitellated infected worms were kept at 30°C for 4 days, spore release ceased and they re-developed a clitellum. These results suggest parasite-induced castration. Comparative monitoring of defecation rate revealed that M. cerebralis reduced feeding activity of T. tubifex by approximately 40%. Low energy intake and impaired energetic allocation may be the underlying mechanism behind reduced fecundity of infected T. tubifex.

scholarly journals Whirling disease in the Crowsnest River: an emerging threat to wild salmonids in Alberta

2021 ◽  
pp. 1-14
Author(s):  
Clayton T. James ◽  
Marie F. Veillard ◽  
Amanda M. Martens ◽  
Emmanuel A. Pila ◽  
Alyssa Turnbull ◽  
...  
Keyword(s):  
Clinical Signs ◽  
Fish Populations ◽  
Tubifex Tubifex ◽  
Weight Of Evidence ◽  
Whirling Disease ◽  
Myxobolus Cerebralis ◽  
Parasite Life Cycle ◽  
Life Cycle Stages ◽  
Water Fish ◽  
Study Sites

We provide the first documented case of whirling disease (WD) impacts to wild, self-sustaining rainbow trout (RNTR, Oncorynchus mykiss) populations in Canada. Myxobolus cerebralis (Mc), the causative agent of WD, was first confirmed in Alberta in 2016. However, evidence of disease in local fish populations was unknown. Using a weight-of-evidence approach, we examined multiple parasite life cycle stages in the Crowsnest River, Alberta. Percentage of infected Tubifex tubifex worms actively shedding triactinomyxons (TAMs) exceeded known thresholds of Mc establishment and TAM densities instream exceeded thresholds known to cause ≥90% declines in RNTR populations. Mc was detected at 5 of 6 study sites in water, fish, and worms. Disease severity was highest in the lower watershed where 100% of sentinel fish tested positive for Mc 7 to 14 days post-exposure; up to 85% of wild fingerling RNTR showed clinical signs of disease and yearling trout were largely absent from the river suggesting reduced survival. Our findings indicate conditions necessary for outbreak of WD exist in Alberta, highlighting the need to consider this disease as an emerging threat to wild salmonid populations.

Whirling Disease: Reviews and Current Topics

2002 ◽  
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Positive Control ◽  
Negative Control ◽  
Infected Fish ◽  
Tubifex Tubifex ◽  
Potential Contribution ◽  
Whirling Disease ◽  
Myxobolus Cerebralis ◽  
Dead Fish

<em>ABSTRACT. </em>In Colorado, Windy Gap Reservoir is a focus of <em>Myxobolus cerebralis </em>infectivity of greater intensity than may be explained by the potential contribution of <em>M. cerebralis </em>myxospores by dead fish. One mechanism that would help explain this situation is the expulsion of viable <em>M. cerebralis </em>myxospores by living infected fish. We conducted laboratory experiments to see if <em>Tubifex tubifex</em>, purged of infection by incubation at 26°C for a minimum of 30 d, could become reinfected by exposure to feces and wastes from aquaria containing <em>M. cerebralis</em>-infected brown trout <em>Salmo trutta</em>. In two separate experiments, replicate experimental units of <em>T. tubifex </em>were thoroughly infected in this manner. By comparison, evidence of infection in negative control replicates was much weaker in both experiments. It is possible that the purging process used to remove initial infection was not 100% effective, yet the differences between experimental and negative control replicates were dramatic. Positive control replicates, intentionally exposed to harvested myxospores of <em>M. cerebralis</em>, became heavily infected in both experiments. These results strongly support the hypothesis that brown trout are capable of expelling viable <em>M. cerebralis </em>myxospores.

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