Tapeworm infection incidence in rural Japan points to a common environmental source of infection

Dhammika Leshan Wannigama; Mohan Amarasiri; Phatthranit Phattharapornjaroen; Cameron Hurst; Yu Suzuki; Daisuke Akaneya; Mika Moriya; Taichi Adachi; Yoshikazu Okuma; Daisuke Ishizawa; Hitoshi Ishikawa; Kazuhiko Miyanaga; Longzhu Cui; Kazunori Moriya; Hirotake Mori; Naveen Kumar Devanga Ragupathi; Yoshitaka Shimotai; Daisuke Sano; Takashi Furukawa; Kazunari Sei; Talerngsak Kanjanabuch; Paul G. Higgins; Tetsuji Aoyagi; Anthony Kicic; Sam Trowsdale; Parichart Hongsing; Aisha Khatib; Kenji Shibuya; Shuichi Abe; Hiroshi Hamamoto

doi:10.5582/ddt.2025.01070

Brief Report

Tapeworm infection incidence in rural Japan points to a common environmental source of infection

Dhammika Leshan Wannigama ^†, Mohan Amarasiri ^†, Phatthranit Phattharapornjaroen, Cameron Hurst, Yu Suzuki, Daisuke Akaneya, Mika Moriya, Taichi Adachi, Yoshikazu Okuma, Daisuke Ishizawa, Hitoshi Ishikawa, Kazuhiko Miyanaga, Longzhu Cui, Kazunori Moriya, Hirotake Mori, Naveen Kumar Devanga Ragupathi, Yoshitaka Shimotai, Daisuke Sano, Takashi Furukawa, Kazunari Sei, Talerngsak Kanjanabuch, Paul G. Higgins, Tetsuji Aoyagi, Anthony Kicic, Sam Trowsdale, Parichart Hongsing, Aisha Khatib, Kenji Shibuya, Shuichi Abe, Hiroshi Hamamoto

Author information

Dhammika Leshan Wannigama ^†
Department of Infectious Diseases and Infection Control, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Pathogen Hunter's Research Collaborative Team, Department of Infectious Diseases and Infection Control, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Yamagata Prefectural University of Health Sciences,Yamagata, Japan.
Department of Infectious Diseases, Faculty of Medicine, Yamagata University, Yamagata, Japan.
School of Medicine, Faculty of Health and Medical Sciences, The University of Western Australia, Nedlands, Western Australia, Australia.
Biofilms and Antimicrobial Resistance Consortium of ODA receiving countries, The University of Sheffield, Sheffield, United Kingdom.
The Lygodium Ceylon Health and Environmental Policy Research Center, Colombo, Sri Lanka.
Mohan Amarasiri ^†
Pathogen Hunter's Research Collaborative Team, Department of Infectious Diseases and Infection Control, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University, Sendai, Miyagi, Japan.
Phatthranit Phattharapornjaroen
Pathogen Hunter's Research Collaborative Team, Department of Infectious Diseases and Infection Control, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Faculty of Health Science Technology, Chulabhorn Royal Academy, Bangkok, Thailand.
HRH Princess Chulabhorn Disaster and Emergency Medicine Center, Chulabhorn Royal Academy, Bangkok, Thailand.
Cameron Hurst
Pathogen Hunter's Research Collaborative Team, Department of Infectious Diseases and Infection Control, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Center of Excellence in Applied Epidemiology, Thammasat University, Rangsit, Thailand.
Department of Clinical Epidemiology, Faculty of Medicine, Thammasat University, Rangsit, Thailand.
Yu Suzuki
Department of Clinical Laboratory, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Daisuke Akaneya
Department of Clinical Laboratory, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Mika Moriya
Department of Clinical Laboratory, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Taichi Adachi
Department of Clinical Laboratory, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Yoshikazu Okuma
Department of Pharmacy, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Daisuke Ishizawa
Department of Pharmacy, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Hitoshi Ishikawa
Pathogen Hunter's Research Collaborative Team, Department of Infectious Diseases and Infection Control, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Yamagata Prefectural University of Health Sciences,Yamagata, Japan.
Kazuhiko Miyanaga
Division of Bacteriology, School of Medicine, Jichi Medical University, Tochigi, Japan.
Longzhu Cui
Division of Bacteriology, School of Medicine, Jichi Medical University, Tochigi, Japan.
Kazunori Moriya
Department of Infectious Diseases and Infection Control, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Pathogen Hunter's Research Collaborative Team, Department of Infectious Diseases and Infection Control, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Hirotake Mori
Department of General Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan.
Naveen Kumar Devanga Ragupathi
Biofilms and Antimicrobial Resistance Consortium of ODA receiving countries, The University of Sheffield, Sheffield, United Kingdom.
Division of Microbial Interactions, Department of Research and Development, Bioberrys Healthcare and Research Centre, Vellore, India.
Yoshitaka Shimotai
Department of Infectious Diseases, Faculty of Medicine, Yamagata University, Yamagata, Japan.
Daisuke Sano
Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University, Sendai, Miyagi, Japan.
Department of Frontier Sciences for Advanced Environment, Graduate School of Environmental Studies, Tohoku University, Sendai, Miyagi, Japan.
Takashi Furukawa
Laboratory of Environmental Hygiene, Department of Health Science, School of Allied Health Sciences, Kitasato University, Sagamihara-Minami, Kanagawa, Japan.
Kazunari Sei
Laboratory of Environmental Hygiene, Department of Health Science, School of Allied Health Sciences, Kitasato University, Sagamihara-Minami, Kanagawa, Japan.
Talerngsak Kanjanabuch
Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Center of Excellence in Kidney Metabolic Disorders, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Dialysis Policy and Practice Program (DiP3), School of Global Health, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Peritoneal Dialysis Excellence Center, King Chulalongkorn Memorial Hospital, Bangkok, Thailand.
Paul G. Higgins
Institute for Medical Microbiology, Immunology and Hygiene, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.
German Centre for Infection Research, Partner site Bonn-Cologne, Cologne, Germany.
Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.
Tetsuji Aoyagi
Department of Infectious Diseases, Internal Medicine, Tohoku University Graduate School of Medicine, Miyagi, Japan.
Anthony Kicic
Wal-Yan Respiratory Research Centre, Telethon Kids Institute, University of Western Australia, Nedlands, Western Australia, Australia.
Centre for Cell Therapy and Regenerative Medicine, Medical School, The University of Western Australia, Nedlands, Western Australia, Australia.
Department of Respiratory and Sleep Medicine, Perth Children's Hospital, Nedlands, Western Australia, Australia.
School of Population Health, Curtin University, Bentley, Western Australia, Australia.
Sam Trowsdale
School of Environment, University of Auckland, Auckland, New Zealand.
Parichart Hongsing
Pathogen Hunter's Research Collaborative Team, Department of Infectious Diseases and Infection Control, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Department of Infectious Diseases, Faculty of Medicine, Yamagata University, Yamagata, Japan.
Aisha Khatib
Department of Family & Community Medicine, University of Toronto, Toronto, ON, Canada.
Kenji Shibuya
Tokyo Foundation for Policy Research, Tokyo, Japan.
Shuichi Abe
Department of Infectious Diseases and Infection Control, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Pathogen Hunter's Research Collaborative Team, Department of Infectious Diseases and Infection Control, Yamagata Prefectural Central Hospital, Yamagata, Japan.
Hiroshi Hamamoto
Department of Infectious Diseases, Faculty of Medicine, Yamagata University, Yamagata, Japan.
Author contributions

†These authors contributed equally: Dhammika Leshan Wannigama, Mohan Amarasiri

Keywords: Tapeworm infection, rural Japan, Dibothriocephalus nihonkaiensis, environmental source of infection

JOURNAL FREE ACCESS

2025 Volume 19 Issue 5 Pages 351-357

DOI https://doi.org/10.5582/ddt.2025.01070

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Abstract

Dibothriocephalus nihonkaiensis is a zoonotic tapeworm transmitted to humans through consumption of raw or undercooked fish or wild meat. Between 2022 and 2023, Yamagata Prefecture reported an increase in cases compared with 2017–2021, when none were observed. We conducted a clinical and environmental investigation to clarify infection sources. Four confirmed and one suspected patient were identified, all presenting with gastrointestinal symptoms. Exposures were linked to raw cherry salmon (Oncorhynchus masou) in three cases and undercooked bear meat in one case. Praziquantel treatment (10–20 mg/kg) was effective, with eight worms (76–210 cm) recovered. Environmental surveillance detected D. nihonkaiensis in 33.3% of bear feces (20/60) and 21.8% of wild fish samples (17/78). Phylogenetic analysis showed close genetic relatedness among human, bear, and fish isolates, indicating a shared transmission cycle. These findings confirm zoonotic transmission of D. nihonkaiensis in Yamagata and highlight the need for food safety awareness and environmental monitoring.

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