Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish

Steinhausia sp. (Cockle Egg Disease)

Category | Common Name | Scientific Name | Distribution | Host Species
Impact on Host | Diagnostic Technique | Methods of Control | References | Citation

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Category

Category 3 (Host Not in Canada)

Common, generally accepted names of the organism or disease agent

Cockle egg disease, Microsporidiosis of cockle eggs.

Scientific name or taxonomic affiliation

Steinhausia sp., Steinhausia-like microsporidian. Comtet et al. (2003) speculated on possibility that the parasite in cockles may be Steinhausia mytilovum because infected population of mussels were located in the vicinity of the infected cockles.

Geographic distribution

Europe including Spain (Carballal et al. 2001) and France (Comtet et al. 2003).

Host species

Cerastoderma edule. Microsporidian parasites have also been reported from the ova of the clam Macoma balthica in Maryland, U.S.A. (Farley 1977).

Impact on the host

All infections occur in the cytoplasm of cockle oocytes (=ovocytes) and ova within the gonadal tissues. Prevalence of infection in cockles from Baie des Veys, France ranged from 11.8% to 20.0% in buried and surface cockles respectively (Comtet et al. 2003). The intensity of infection is usually low with local, minor haemocyte infiltration but without significant pathological damage to the host. However, Steinhausia sp. could affect the the viability of the infected ova and possibly cockle fecundity.

Diagnostic techniques

Squash Preparations: The parasite is evident microscopically within the ova in wet mount preparations of the gonadal tissue pressed between a glass slide and coverslip.

Histology: Sporocysts (usually elliptical to circular in shape from 16 to 31 µm in diameter) containing up to 30 spherical spores (2 to 3.2 µm in diameter) within the cytoplasm of well developed oocytes and mature ova. Although there is usually only one sporocyst per ovum, two sporocysts were observed in a few oocytes. Generally, the morphology of the Microsporida in cockle eggs resembles that of Steinhausia mytilovum in Mytilus spp. and Steinhausia ovicola in Ostrea edulis.

Methods of control

Cockles from infected populations, or cockles grown in proximity to infected populations, should not be introduced into unaffected areas.

References

Carballal, M.J., D. Iglesias, J. Santamarina, B. Ferro-Soto and A. Villalba. 2001. Parasites and pathologic conditions of the cockle Cerastoderma edule populations of the coast of Galicia (NW Spain). Journal of Invertebrate Pathology 78: 87-97.

Comtet, T., C. Garcia, Y. Le Coguic and J.P. Joly. 2003. Infection of the cockle Cerastoderma edule in the Baie des Veys (France) by the microsporidian parasite Steinhausia sp. Diseases of Aquatic Organisms 57: 135-139.

Farley, C.A. 1977. Neoplasms in estuarine mollusks and approaches to ascertain causes. In: Kraybill, H.F., C.J. Dawe, J.C. Harshbarger, R.G. Tardiff (eds.) Aquatic Pollutants and Biologic Effects with Emphasis on Neoplasia, Vol. 298. The New York Academy of Sciences, New York. pp. 225-232.

 

Citation Information

Bower, S.M. (2007): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Steinhausia sp. (Cockle Egg Disease).

URL: http://www.pac.dfo-mpo.gc.ca/science/species-especes/shellfish-coquillages/diseases-maladies/pages/cedcc-eng.htm

Date last revised: May 2007
Comments to Susan Bower