• Journal of fish pathology
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• v.11 no.1
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• pp.69-76
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• 1998

An apicomplexan parasite, Perkinsus sp. was observed from the cultured baby clams, Ruditapes philippinarum, collected from the coast of Kochang and Taean (South Korea), where it caused seasonal mortality of clams. Several milky-white cysts were observed on the surface of gill and visceral mass of parasitised clams. The trophozoites of parasite had eccentric nucleus and proliferated by schizogony in gill, mantle, hepatopancrease and reproductive tissues, resulting in the formation of granuloma and the intensive infiltration of hemocytes in the tissues. During incubation in FTM, trophozoites increased in size, resulting in prezoosporangia which appeared as round black spheres when colored with Lugols iodine solution. The prevalence of Perkinsus sp. in clams was Kochang, 73.1%; Taean, 94.8% (during 9-mo. survey) and showed size-dependent infection. Hemacolor kit was useful to reduce time for diagnosis of the trophozoite of Perkinsus sp. that has been responsible of massive motalities in the clam.