Sphenophrya-like Ciliates of Oysters
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Category
Category 4 (Negligible Regulatory Significance in Canada)
Common, generally accepted names of the organism or disease agent
Sphenophrya-like ciliates, sphenophyriid infection.
Scientific name or taxonomic affiliation
Sphenophrya-like ciliates.
Geographic distribution
On oysters from eastern and western U.S., Canada, Europe and Scandinavia. May be ubuquitous.
Host species
Crassostrea virginica, Crassostrea gigas, Ostrea edulis and other bivalves including mussels, clams and cockles. Different species may occur in different species of oysters.
Impact on the host
Effects not well-established. Large numbers can be observed with no obvious host-response. Small numbers (fewer than 1%) are intracellular and may cause massive hypertrophy of the host cell and its nucleus (xenoma). The only pathology described to date was this xenomic response reported for sphenophyrids from C. virginica from the eastern United States. No mortalities have been associated with sphenophryiid infections.
Diagnostic techniques
Histology
Examine transverse sections through the gill and palp area for pear-shaped ciliates with large, densely basophilic nuclei attached to the gill and palp surfaces. More rarely found within the gill epithelium with or without xenoma.
Methods of control
No known methods of prevention or control.
References
Fenchel, T. 1965. Ciliates from Scandinavian Molluscs. Ophelia 2(1): 71-174.
Otto, S. V., Harshbarger, J. C. and Chang, S. C. 1979. Status of selected unicellular eucaryote pathogens, and prevalence and histopathology of inclusions containing obligate prokaryote parasites in commercial bivalve mollusks from Maryland estuaries. Haliotis 8 (1977): 285-295.
Sprague, V. 1970. Some protozoan parasites and hyperparasites in marine bivalve molluscs. American Fisheries Society Special Publication 5: 511-526.
Citation Information
Bower, S.M., McGladdery, S.E., Price, I.M. (1994): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Sphenophrya-like Ciliates of Oysters.
Date last revised: Fall 1994
Comments to Susan Bower
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