Cryptosporidiosis of Clams
Category 3 (Host Not in Canada)
Common, generally accepted names of the organism or disease agent
Cryptosporidiosis of clams.
Scientific name or taxonomic affiliation
Cryptosporidium sp. of the phylum Apicomplexa and class Sporozoa, normally occurs in the gastro-intestinal and/or respiratory tract of vertebrates, this is the only know occurrence in a marine molluscan species. Positive identification can not be established until all life cycle stages of this parasite have been found.
Estuarine region of the south of Portugal.
Tapes (=Ruditapes) decussatus.
Impact on the host
Found in the branchial epithelium of clams from an area where high clam mortalities occurred.
Histology: Several ovoid to piriform uninucleate merozoites (1.6-1.8 µm long and 0.6-0.8 µm wide) within a parasitophorous vacuole within gill epithelial cells that were frequently lysed.
Electron Microscopy: About 54 merozoites per parasitophorous vacuole each with a typical apical complex formed mainly by conoid (consisting of about 16 longitudinal microtubules), rhoptries, polar ring and subpellicular microtubules.
Methods of control
No known methods of prevention or control.
Azevedo, C. 1989. Ultrastructural observations of Cryptosporidium sp. parasite of Ruditapes decussatus (Mollusca, Bivalvia). Journal of Invertebrate Pathology 54: 23-27.
Bower, S.M. (1996): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Cryptosporidiosis of Clams.
Date last revised: September 1996
Comments to Susan Bower
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