Gnathostoma spinigerum

This parasite is found in the esophagus and stomach of cats and dogs in Asia and Oceania. Humans become infected by eating raw or undercooked fish. Larvae move around in the human body, causing edema and welts. In rare cases, larvae migrate to the eyes and brain, causing severe damage.

A related species, Gnathostoma hispidum, causes similar symptoms. Although G. hispidum is not normally found in Japan, there have been cases of Japanese who were infected by eating imported raw loach fish.