Gregarine Parasitism of Lobsters


Category 4 (Negligible Regulatory Significance in Canada)

Common, generally accepted names of the organism or disease agent

Gregarine parasitism of lobsters.

Scientific name or taxonomic affiliation

  1. Porospora (=Gregarina) gigantea.
  2. Porospora nephropis.

Geographic distribution

  1. East coast of Canada, and the Atlantic and Mediterranean coasts of France.
  2. Northern part of France.

Host species

  1. Homarus americanus.
  2. Nephrops norvegicus.

Impact on the host

No gross pathological changes were associated with infection although several hundred gregarines were observed in some lobsters. There may be a seasonal trend in the prevalence of infection which usually exceeds 50% in lobsters with a carapace length more than 50 mm.

Diagnostic techniques

Gross Observations: White cysts (0.25-0.5 mm diameter) along the inside walls of the posterior intestine and rectum.

Squash Preparations: Charasteristic spherical gamonocysts (about 300 µm in diameter) attached to the cuticular lining of the rectum, and thread-like trophic stages (up to 16 mm long) found in the lumen of the intestine.

Methods of control

No known methods of prevention or control.


Boghen, A.D. 1978. A parasitological survey of the American lobster Homarus americanus from the Northumberland Strait, southern Gulf of St. Lawrence. Canadian Journal of Zoology 56: 2460-2462.

Brattey, J. and A. Campbell. 1986. A survey of parasites of the American lobster, Homarus americanus (Crustacea: Decapoda), from the Canadian Maritimes. Canadian Journal of Zoology 64: 1998-2003.

Sprague, V. 1970. Some protozoan parasites and hyperparasites in marine decapod crustacea. American Fisheries Society Special Publication 5: 416-430.

Théodoridès, J. and M. Laird. 1970. Quelques Eugrégarines parasites d' invertébrés marins de St. Andrews (Nouveau-Brunswick). Canadian Journal of Zoology 48: 1013-1016.

Citation Information

Bower, S.M. (1996): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Gregarine Parasitism of Lobsters.

Date last revised: September 1996
Comments to Susan Bower

Date modified: