Immunodiagnosis of human trichinellosis using excretory-secretory (ES) antigen

Infective first stage larvae of Trichinella spiralis were recovered from muscles of laboratory infected mice by digesting the muscles with 1% HC1-1% pepsin and collecting the larvae by modified Baerman's method. The larvae were cultivated in a serum-free medium for 18 h. The ES antigen obtained from the culture medium was used in an enzyme-linked immunosorbent assay (ELISA) for detecting IgG antibodies to T. spiralis in serum samples collected from three groups of individuals. The individuals of the first group were parasitologically confirmed trichinellosis patients, while those of group 2 were patients with other helminthiasis and group 3 were healthy, parasite-free individuals. The specificity of the assay was 100%. The sensitivity of the test was also 100% when performed on sera of group 1 collected at days 57 and 120 after infection. Sera collected earlier (day 23) and those collected 700 days after infection had negligible reactivity. Thus IgG-ELISA using ES antigen of the L1 was useful not only for diagnosis but also in evaluation of cure. Western blot analysis revealed that specific antigens of T. spiralis were 94, 67, 63, and 39 kilodalton components.