Enzyme-linked immunosorbent assay for detection of antibody to Gnathostoma antigen in patients with intermittent cutaneous migratory swelling.

A sensitive enzyme-linked immunosorbent assay is described for the detection of immunoglobulin G antibody to Gnathostoma antigen in the sera of patients with intermittent cutaneous migratory swelling who were suspected of being infected by the tissue nematode Gnathostoma spinigerum. The antigen used was a crude somatic aqueous extract of the third larval stage obtained from naturally infected eels. The 1:320 dilution of all sera from 46 patients gave enzyme-linked immunosorbent assay values above the mean (+2 standard deviations) of normal healthy controls, which was arbitrarily used as a cutoff point. The sera from patients suspected of being infected by another tissue nematode, Angiostrongylus cantonensis, as well as from patients with intestinal roundworm infections, also reacted weakly in the test system used in this study. Nonetheless, when the assay was carried out using both Gnathostoma and Angiostrongylus antigens simultaneously, it appeared to be a reliable laboratory test that can be used to support a clinical diagnosis of gnathostomiasis in patients with intermittent cutaneous migratory swelling.