貝類のパーキンサス原虫症

摘要

パーキンサス原虫とはパ1一キンサス属の原生動物の総称で，貝類に寄生する病原体として知られている。 Perkinsus species are pathogenic protistan parasites of mollusks and have been damaging mollusk industries in some areas in the world. In North America, P. marinus possibly invaded from overseas in the 1940 and destroyed the oyster industry in association with andfher piotistan Haplosporidium nehoni in the Atlantic coast of USA, In Japan, Perkinsus oheni is present in Manila clam, Venerupis philippinarum, the annual production of which has been greatly decreasing for two decades Although the causative factors of the decreasing production of Manila clam have not been clarified yet, our recent challenge experiments demonstrated that P. oheni may be much more pathogenic in juvenile clams than in adult clams, suggesting the possible involvement of the parasite in the decrease of Manila clam. Mass mortalities of P. oheni have been reported from abalones in Australia But, mortalities caused by the parasite have not been found in abalones in Japan, in spite of its high prevalence in Manila clams. The pathogenecity of P. oheni might vary between strains in mania clams and ones in abalones in Australia Further study is needed to clarify the pathogenecity of different P. oheni strains. Mass mortlities were caused by Perkinsus qugwadi in Japanese scallop Patinopecten yessoensis transplanted into British Columbia, Canada, The parasite may be indigenous species in British Columbia and demonstrated strong pathogenicity after host switch to newly transplanted Japanese scallop. If the parasite invades Japan, scallop industry will be damaged enormously. We have to make the greatest possible effort to prevent the invasion of the parasite.