Mycoplasma-like Infection of Cockles


Category 3 (Host Not in Canada)

Common, generally accepted names of the organism or disease agent

Mycoplasma-like infection of cockles.

Scientific name or taxonomic affiliation

Mycoplasma-like microorganism.

Geographic distribution

Estuarine region of central Portugal.

Host species

Cerastoderma edule.

Impact on the host

Observed in the gill epithelial cells of gaping C. edule during the occurrence of high mortalities among this species. However, the disease was not transmitted in the laboratory to healthy C. edule by incubating them with several gaping individuals for 15 days during which time some died and were not removed for 2 subsequent days. Infected cells had a pycnotic nucleus and evidence of cytoplasmic lysis with numerous vacuoles, few mitochondria and no ribosomes. Adjacent uninfected cells appeared normal.

Diagnostic techniques

Histology: Numerous rod shaped organisms regularly distributed in well organized arrays in the basal portion of gill epithelial cells.

Electron Microscopy: Organisms 0.5 to 4.0 µm in length and a uniform width of 0.9 µm containing homogeneous and electron-dense material delimited by a tri-laminar membrane without a cell wall were arranged in layers within cytoplasmic cisternae in the epithelial cells.

Methods of control

No known methods of prevention or control. However, mortalities were associated with high temperatures during the summer.


Azevedo, C. 1993. Occurrence of an unusual branchial mycoplasma-like infection in cockle Cerastoderma edule (Mollusca, Bivalvia). Diseases of Aquatic Organisms 16: 55-59.

Citation Information

Bower, S.M. (1996): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Mycoplasma-like Infection of Cockles.

Date last revised: September 1996
Comments to Susan Bower

Date modified: