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Discovery of a new North American parasitic worm in snakes from the Kanto region

Are snakes in Honshu facing tough times?
A. The Japanese striped snake E. quadrivirgata infected with O. elongatum (dark arrows). B. The freshwater snail Âé¶¹ÒùÔºella acuta. C. Ochetosoma elongatum. Credit: Dr. Tsukasa Waki

A research group has discovered a new North American trematode, Ochetosoma elongatum, for the first time in Japan in the oral cavities of three native snake species in the Kanto region.

In addition to investigating its in the wild, the authors conducted a comprehensive literature review to explore the route of invasion of this parasite. The findings of this study were in Parasitology International.

Ochetosoma elongatum is a snake trematode which is distributed in North America. However, the adult was discovered for the first time in Japan in the mouths of three native species in the Kanto region. A previous study reported the presence of a related North American trematode (Ochetosoma kansense) in western Japan, indicating that the two North American trematodes are now infecting native snakes in Japan.

Are snakes in Honshu facing tough times?
Life cycle of Ochetosoma elongatum in Japan. Credit: Dr. Tsukasa Waki

The sporocysts and cercariae were detected in the North American freshwater snail Âé¶¹ÒùÔºella acuta, which has introduced and established its population in Japan. The cercarae is thought to infect frogs and develop into metacercariae. The metacercariae develop into adults after the host frog was fed by the Japanese snakes, the definitive host.

The snail Âé¶¹ÒùÔºella acuta are thought to be introduced to Japan with imported freshwater plants for aquariums. The increased demand for ornamental fish and exotic pets likely led to the introduction of infected Âé¶¹ÒùÔºella acuta snails and/or North American snakes, resulting in the introduction of this parasite to Japan.

The study's authors included Harushige Seo (an undergraduate student), Eriko Ansai (a graduate student), Tetsuya Sase (an undergraduate student), Associate Professor Tsukasa Waki, and Lecturer Yosuke Kojima from the Faculty of Science, Toho University.

More information: Harushige Seo et al, Introduction of a snake trematode of the genus Ochetosoma in eastern Japan, Parasitology International (2024).

Provided by Toho University

Citation: Discovery of a new North American parasitic worm in snakes from the Kanto region (2024, October 1) retrieved 8 June 2025 from /news/2024-10-discovery-north-american-parasitic-worm.html
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