Geographic distribution Korea and Japan. Host species Crassostrea gigas .
Parasites infect the cytoplasm of oocytes and can affect large areas of reproductive follicles.
Infected eggs may be liberated or retained in the ovarian follicle. Within the secondary cells, there may be development of sporonts which give rise to one tertiary cell by endogenous budding. Each tertiary cell forms one tricellular spore by internal cleavage. No known methods of prevention or control. Infected oysters should not be transported into areas known to be free of the disease.