Kidney Coccidia of Oysters


Category 1 (Not Reported in Canada)

Common, generally accepted names of the organism or disease agent

Oyster kidney coccidians.

Scientific name or taxonomic affiliation

Unidentified species of coccidia.

Geographic distribution

Auray, France. Although various species of coccidia have been observed in other species of bivalves in Canada (such as mussels and clams), none have been reported from oysters.

Host species

Ostrea edulis.

Impact on the host

Infected kidney epithelial cells become extremely hypertrophied. Heavy infections may cause serious kidney damage but associated mortalities have not been reported in oysters.

Diagnostic techniques

Squash Preparations: Preliminary diagnosis can be made on the presence of large mature macrogamonts in squashes of kidney tissues.

Histology: Various stages of the coccidia can be observed in the cytoplasm of kidney epithelial cells.

Methods of control

No known methods of prevention or control.


Lauckner, G. 1983. Diseases of Mollusca: Bivalvia. In O. Kinne [ed.]. Diseases of Marine Animals. Volume II: Introduction, Bivalvia to Scaphopoda. Biologische Anstalt Helgoland, Hamburg. p. 548-549.

Citation Information

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

Date last revised: Fall 1994
Comments to Susan Bower

Date modified: