Isolated optic neuritis from an identified Gnathostoma spinigerum.

PURPOSE To describe a patient with isolated monocular optic neuritis caused by an identified Gnathostoma spinigerum infestation. CASE REPORT A 21-year-old man developed a swollen eyelid and painful monocular visual loss of his left eye which did not improve after treatment by intravenous steroid and albendazole. A remarkable eosinophilia in his peripheral blood count was demonstrated. The patient subsequently found a live parasite emerged from his lower eyelid and it was successfully removed by himself. Gross and histopathology examinations of the obtained parasite was undertaken. The parasite was identified as Gnathostoma spinigerum. His blood test for Gnathostoma antibody was positive. DISCUSSION The etiology of isolated optic neuritis in this patient was Gnathostoma spinigerum which was confirmed by the histopathology of the obtained parasite and the positive serologic test. CONCLUSIONS We could identify the exact parasite that was proven to cause an isolated optic neuritis. The immediate removal of a causative parasite maynot result in an improvement of the injured tissue but is beneficial in preventing further destruction as well as future complications.