Marteilia-like Parasite of Giant Clams


Category 3 (Host Not in Canada)

Common, generally accepted names of the organism or disease agent

Marteilia-like parasite of giant clams.

Scientific name or taxonomic affiliation

Marteilia-like protistan.

Geographic distribution


Host species

Tridacna maxima.

Impact on the host

Visible lesions in the kidney were associated with the displacement of a majority of the kidney tissue by cyst-like structures. Although information on prevalence, morbidity and mortality rate was not reported, damage observed in the kidney suggests that it is potentially pathogenic for this species.

Diagnostic techniques

Gross Observations: Numerous chalk-white foci are visible throughout the dark red-brown kidney.

Histology: Kidney lesions appear as numerous cyst-like structures lined with ciliated columnar epithelium. Within the cysts are groups of protistan cells (about 2 µm diameter) with punctate nuclei. They are enclosed within a larger cellular unit (about 4 µm diameter) which stain grey like the cytoplasm of the smaller cells (H & E stain). Further from the epithelial lining these cells have an eosinophilic colour, indistinct outlines, and contain irregular-shaped refringent bodies.

Electron Microscopy: The 2-µm cells contain vermiform organelles and haplosporosomes similar to those in spores of Marteilia sydneyi.

Methods of control

No known methods of prevention or control.


Norton, J.H., F.O. Perkins and E. Ledua. 1993. Marteilia-like infection in a giant clam, Tridacna maxima in Fiji. Journal of Invertebrate Pathology 61: 328-330.

Citation Information

Bower, S.M., McGladdery, S.E., Price, I.M. (1994): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Marteilia-like Parasite of Giant Clams.

Date last revised: Fall 1994
Comments to Susan Bower

Date modified: