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A sporozoan coccidian genus (order Eucoccidiida, family Haemogregarinidae) that parasitizes the blood cells of cold-blooded animals and the digestive system of invertebrate primary hosts in an obligatory two-host cycle.
[G. haima, blood, + L. grex, a flock]
a genus of protozoa parasitic on fish. Includes coccidia that cause hepatic necrosis, castration and occlusion of the air bladder.
participates in the production of a leech-vector-transmitted lymphoma in cultured turbot.