Risk assessment of kudoid myxozoans showing asymptomatic infection causing a foodborne disease

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H04540
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Aquatic bioproduction science
• Research Institution: The University of Tokyo
• Principal Investigator: Yokoyama Hiroshi 東京大学, 大学院農学生命科学研究科(農学部), 助教 (70261956)
• Co-Investigator(Kenkyū-buntansha): 河合 高生 地方独立行政法人 大阪健康安全基盤研究所, 微生物部, 主幹研究員 (30250319) ; 小林 彰子 東京大学, 大学院農学生命科学研究科(農学部), 准教授 (90348144)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 魚病学 / 寄生虫 / 食中毒 / 公衆衛生

Outline of Final Research Achievements

As well as a myxosporean Kudoa septempunctata infecting the olive flounder Paralichthys olivaceus, several Kudoa species showing an asymptomatic infection in marine fishes have been recently suspected as causative agents of food-poisoning in humans. In the present study, epizootiological studies on K. hexapunctata from Pacific bluefin tuna Thunnus orientalis indicated that infection with K. hexapunctata were found mostly in juvenile tuna fish less than 1-year old and influenced by nursery ground, rather than origin of seedlings (natural or artificial). Pathogenicity tests with human intestinal epithelial cells (Caco-2 cells) and diarrhea-model animals (suckling mouse) proved that pathogenicity of K. hexapunctata was 1 to 50 lower than that of K. septempunctata. Finally, the lowest limit of K. hexapunctata in tuna muscle was shown to be 10 the 7th power of spores / g-muscle.

Free Research Field

農学