extraintestinal migration by nematode larvae of the order Spiruroidea, not adapted to maturation in the human intestine; caused chiefly by species of Gnathostoma spinigerum and G. hispidum in Japan and Thailand, following ingestion of uncooked fish infected with encapsulated third-stage infective larvae, and possibly by ingestion of infected copepods (the first intermediate host) in contaminated drinking water; the anteriorly spined larvae produce serpiginous tunnels in the skin or may cause subcutaneous or pulmonary abscess, or may invade the eye or brain.