Haplosporidosis of Crabs


Category 1 (Not Reported in Canada)

Common, generally accepted names of the organism or disease agent

Haplosporidosis, Haplosporidian disease.

Scientific name or taxonomic affiliation

Haplosporidium louisiana in mud crabs and an undescribed Minchinia-like species in blue crabs.

Geographic distribution

Eastern coast of the United States.

Host species

Callinectes sapidus as well as several species of mud crabs (i.e., Panopeus herbstii, Eurypanopeus depressus, Rhithropanopeus harrisii).

Impact on the host

Causes haemocytic dysfunction. The disease is considered to be lethal but the prevalence is rare.

Diagnostic techniques

Gross Observations: Sluggishness, drawn haemolymph is opaque white, of low viscosity, and fails to clot properly.

Histology: Masses of uninucleate (3.4-7.3 µm in diameter with nuclei 1.1-2.2 µm in diameter) or multinucleate plasmodial bodies filling vascular spaces and interstitial tissues.

Electron Microscopy: Ultrastructural details indicate that the species in blue crabs is different from those in oysters and mud crabs.

Methods of control

No known methods of prevention or control.


Messick, G.A. and C.J. Sindermann. 1992. Synopsis of principal diseases of the blue crab, Callinectec sapidus. NOAA Technical Memorandum NMFS-F/Nec-88. 24 p.

Newman, M.W., C.A. Johnson and G.B. Pauley. 1976. A Minchinia-like haplosporidan parasitizing blue crabs, Callinectes sapidus. Journal of Invertebrate Pathology 27: 311-315.

Sparks, A.K. 1985. Synopsis of Invertebrate Pathology Exclusive of Insects. Elsevier Science Publishing Co., Amsterdam. p. 294-295.

Citation Information

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

Date last revised: Fall 1994
Comments to Susan Bower

Date modified: