Systematics and transmission ecology of novel liver flukes causing human illness in Ecuador

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H05820
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 海外学術
• Research Field: Parasitology (including sanitary zoology)
• Research Institution: National Institute of Infectious Diseases
• Principal Investigator: Sugiyama Hiromu 国立感染症研究所, 寄生動物部, 主任研究官 (00145822)
• Co-Investigator(Kenkyū-buntansha): 板垣 匡 岩手大学, 農学部, 教授 (80203074) ; 高木 秀和 愛知医科大学, 医学部, 講師 (90288522)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 肝吸虫 / 肝蛭 / 肺吸虫 / エクアドル / 南米

Outline of Final Research Achievements

A three-year joint research project in Ecuador, South America led to the discovery of new endemic areas of the liver fluke belonging to the genus Amphimerus which is responsible for infections among a large number of local residents. The study also identified several freshwater fish species as important sources of human infection. Morphologic features and genome sequencing required for the identification of this species were determined. In addition, the whole mitochondrial DNA was sequenced and registered (GenBank Accession No. MK238505). Experimental infection studies with the Amphimerus-metacercariae using hamster as the test animal featured the pathological changes: the biliary mucosa became edematous and epithelial hyperplasia was way marked. Fibrosis was prominent but the level of cirrhosis was not so severe. The liver fluke belonging to the genus Fasciola and the lung fluke belonging to the genus Paragonimus were also studied.

Free Research Field

寄生虫学

Academic Significance and Societal Importance of the Research Achievements

本研究では、エクアドルに分布する肝吸虫と、さらに肝蛭および肺吸虫を対象として、汚染実態を解明し、各寄生虫症の予防法・診断法の確立に取り組んだ。公衆衛生学・地域保健学的にも意義のある研究成果をあげることができ、地域住民の健康被害を予防・解決する成果を得たと考えている。これに加えて、宿主との共進化や寄生虫の種間競合などの学術的課題に繋がる話題も提供でき、吸虫類の種分化や進化機構を理解・解決するために重要な問題点も提示できたと考えている。