Newly recognized causative larval nematode (Suborder :Spirurina) of creeping eruption.

Gnathostoma are parasites of wild mammals and larval stages of 3 native species, G. spinigerum, G. doloresi and G. nipponicum have been found in cold blooded vertebrates. Moreover, larval G. hispidum has been found in loaches imported to Japan from east Asia (Akahane et ai, 1982). Among these species, G. spinigerum had been considered to be the only causative agent of gnathostomiasis until the discovery of G. hispidum (Kitajima et al, 1981), G. nipponicum (Ando et al. 1988) and G. doloresi (Nawa et al, 1989) from specimens biopsied from human cases in Japan. However. since 1985, the number of patients with creeping eruption who had not eaten the presently known intermediate host of gnathostomiasis are increasing (Otaki et al. 1995). In addition, many human cases of ileus have been reported (Kagei et al. 1992; Moritaetal. 1994). Causative larval worms from sections obtained by biopsy from patients resembled the larvae of Spirurina "type x" named by Hasegawa (\978). It was shown that most patients had eaten raw firefly squid and we detected type x larva in the firefly squid. This article describes the present status of creeping eruption by these larvae and morphological features of type x larvae.