Gnathostomiasis possibly caused by Gnathostoma malaysiae

Gnathostomiasis is rarely reported in travelers, although the disease remains a major public health problem in Southeast Asia. A creeping eruption and Quincke's edema (slowly migrating erythema with pruritus) appeared in two Japanese men who had eaten raw freshwater shrimp in Myanmar. A Gnathostoma larva was found in subcutaneous tissue from one of the men. Four species causing human gnathostomiasis, G. hispidum, G. doloresi, G. nipponicum and G. spinigerum, can be distinguished based on the number of nuclei in intestinal epithelial cells of infected larvae, in cross-section. In G. hispidum, only a single large nucleus is found. Morphologically, our larva was initially identified as G. hispidum. However, since the number of epithelial cells was greater and the body width was larger than those of a "large-type" 3rd-stage larva of G. hispidum, the larva was then identified as a 3rd-stage larva of G. malaysiae, Miyazaki and Dun, 1965, as reported by Setasuban et al, (1991). Since no human cases caused by this species of Gnathostoma have previously been encountered, this appears to be the first report of gnathostomiasis due to G. malaysiae.