Human Laryngitis Caused by Clinostomum Complanatum

A 64-year-old Japanese man visited our outpatient department complaining of an irritable sensation in the throat, occurring two days after eating raw freshwater fish (carp sashimi) at a Japanese-style inn. During laryngeal endoscopy, a slow-moving worm (fluke) was found attached to the surface of the right aryepiglottic fold. After inhalation of 4% lidocaine, the fluke was removed using endoscopic forceps. Patient's throat symptoms immediately improved. The worm was microscopically identified as Clinostomum complanatum. C. complanatum is a digenetic trematode that usually infects fish-eating water birds. Clinostomum infections in humans are rare, and only 21 cases have been described in Japan and Korea. C. complanatum infection is known to occur after eating raw freshwater fish, which is a secondary intermediate host. In humans, the metacercariae are released into the stomach and migrate through the esophagus before lodging in the throat. Primary therapy involves endoscopic removal of the worm.