Histopathological lesions of Manila clam, Tapes philippinarum, from Hadong and Namhae coastal areas of Korea.
In order to determine a causal relation between infections and death of Manila clam, Tapes philippinarum, a routine histopathological survey was carried out along the southern coast of Korea from March 1996 to April 1997. Three kinds of parasites (Perkinsus sp., Marteilioides-like organism and Cercaria tapidis) were frequently encountered. The latter two parasites infected the gonad but did not evoke any significant host reaction. However, Perkinsus sp. infestation was characterized by a variable degree of haemocytic encapsulation. Digestive epithelia including those in the digestive diverticula showed various degrees of atrophic changes. Haemocytic infiltration occurred in various tissues and organs also to a variable degree. From the point of view of frequency as well as pathological impact, it was strongly suggested that the atrophy of digestive epithelium, haemocytic encapsulation associated with Perkinsus sp., and haemocytic infiltration in various tissues and organs are lesions that must be carefully monitored for their association with bivalve mortality.