Microsporidiosis of Clams


Category 1 (Not Reported in Canada)

Common, generally accepted names of the organism or disease agent

Microsporidiosis of clams.

Scientific name or taxonomic affiliation

Unidentified microsporidians.

Geographic distribution

  1. Auray, France.
  2. Tred Avon River, Maryland, USA.

Host species

  1. Cerastoderma (=Cardium) edule.
  2. Macoma baltica.

Impact on the host

Pathogenicity unknown.

Diagnostic techniques


  1. Spores (about 2.5 x 1.3 µm) occur in the epithelial cells of the digestive gland.
  2. Parasite is found in the ova and is similar in morphology to Steinhausia mytilovum in Mytilus edulis.

Methods of control

Clams from infected populations or clams grown in proximity to infected populations should not be introduced into unaffected areas.


Comps, M., H. Grizel, G. Tigé and J.-L. Duthoit. 1975. Parasites nouveaux de la glande digestive des mollusques marins Mytilus edulis L. et Cardium edule L. Compte Rendu Hebdomadaire des Séances de l'Académie des Sciences, Série D 281: 179-181.

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

Citation Information

Bower, S.M., McGladdery, S.E., Price, I.M. (1994): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Microsporidiosis of Clams.

Date last revised: Fall 1994
Comments to Susan Bower

Date modified: