Specific
IgE antibody levels in the serum of patients with proven
gnathostomiasis and in those with intermittent cutaneous migratory swelling (CMS) were determined by the
enzyme-linked
immunosorbent assay (ELISA) using somatic extract and excretory-secretory (ES) products of Gnathostoma spinigerum infective larvae as
antigens. The third stage larval used were obtained from naturally infected eels. There was an increase in specific
IgE antibody to both
antigens in these patients. The mean levels of these specific
IgE antibodies were significantly higher than that of the healthy control (P<0.01). Comparison between using somatic extract and ES products in the test showed, a positive result in the group of suspected patients with
gnathostomiasis or CMS was significantly higher when using ES products (81.81%) than somatic extract (59.09%) as the
antigens (P<0.05). However, both somatic and ES
antigens cross-reacted with other parasitic sera. The overall sensitivity of the ELISA for these
IgE antibodies detection were 71.87 per cent and 87.50 per cent with somatic and ES
antigens, respectively. The specificity was 57.53 per cent when somatic
antigen was used and increased to 69.86 per cent when ES
antigen was used. The positive and negative predictive values of the test were 42.59 per cent and 82.35 per cent by using somatic
antigen. Both of these values, were also increased to 56.00 per cent and 92.72 per cent by using the ES
antigen. It is obvious that more potential components may be present in ES products than those in the somatic extract. The ES
antigen may have to be further purified and may be suitable for evaluation of the effectiveness of
chemotherapy. As such, the antibody responses to secreted products are more closely related to active
infection than the anti-whole worm antibody that may persist following the death of the parasites. However, in this disease, the effect of the
IgE antibody on its pathophysiology it is still not known.