Volume 31, Issue 12, December 2025, 102865Author links open overlay panel, , , , Abstract

We report here an asymptomatic patient showing the location of lung lesions that differ between the first and subsequent chest CT scans. This raised suspicion of paragonimiasis, which ultimately led to its diagnosis. For physicians with limited or no experience with paragonimiasis, the observation that the location of lung lesions differs over time on imaging tests is an important clue in suspecting paragonimiasis. Moreover, this patient was co-infected with liver fluke. Even when one kind of parasitic infection is identified, it is important to be aware of other parasitic infections.

Introduction

Paragonimiasis, also known as lung fluke infection, is a foodborne parasitic disease caused by infection with genus Paragonimus. Human infection occurs by ingestion of raw or undercooked freshwater crab, crayfish, or mammalian meat that contains the infective larval stage of this parasite. In parasitic diseases, imaging studies can provide a variety of findings. In particular, findings in which the site of the lesion varies over time indicate that the site of the lesion migrates, an important finding that is suggestive of parasitic disease. This report describes a Thai patient who was infected with Paragonimus in Japan and had migratory lesions in the lungs on chest CT scans and who, in addition, was also infected with a liver fluke infection.

Section snippetsCase report

A Thai-man in his early 20s, previously healthy and asymptomatic, was referred to Nabari City Hospital (NCH) for a detailed examination and treatment 10 days later after a left lung consolidation was incidentally discovered during a chest X-ray taken as part of a comprehensive physical examination. Physical findings at the first visit were as follows: height 176cm, weight 83kg, alert consciousness, blood pressure 130/60 mmHg, pulse 80/min, oxygen saturation 97 %, and body temperature of

Discussion

The different locations of the lesion on chest CT scans at the initial visit and 16 days later suggested that the lesion had migrated. This finding led us to strongly suspect pulmonary paragonimiasis. The differing sites of lesions over time is an important finding suggesting that the parasite is migrating in the body of its host. If imaging of the chest shows a migration of lesions over time, paragonimiasis should be considered.

The patient ate raw freshwater crab (G. dehaani) caught in a river

Patient consent

Written informed consent for publication was obtained from the patient.

Authorship statement

All authors meet the ICMJE authorship criteria.

Author contributions

KO, HW, KoS and YI involved in the patient's care. KaS evaluated the stool parasitological examination. KO was involved in draft preparation and all authors (KO, KaS, HW, KoS and YI) gave final approval of the manuscript.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or non-for-profit sectors.

Declaration of competing interests

The authors have no competing interests to declare.

Acknowledgments

The authors would like to thank Professor Haruhiko Maruyama and the staff of the Division of Parasitology, Department of Infectious Diseases, Faculty of Medicine at Miyazaki University for conducting the serological diagnosis of paragonimiasis using microplate ELISA. We also express our deep gratitude to Ms. Michels Katherine Jordan, Department of Medical Technology, Faculty of Health Science, Suzuka University of Medical Science, for English proofreading and correction.

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