Resumo:
Strongyloidiasis is a neglected parasitic disease which prevalence might
be underestimated in many countries, it has a particular importance among
immunosuppressed patients due to the risk of hyperinfection, which might be fatal.
Early diagnosis is essential to prevent the serious forms of the disease, but the
methods used nowadays involve looking larvae in the feces, technique which only
raises its sensitivity through repetitions using fecal samples collected on alternate
days. Immunological methods, especially the Enzyme-Linked Immunosorbent Assay
(ELISA), are practical and able to test several samples at once, but still lack of
standardization with an antigen easy to obtain and reproduct. The aim of this study is
to evaluate the efficiency of the crude antigen extracts of S. stercoralis and S.
venezuelensis and their fractions higher and lower than 100 kDa for the
immunodiagnosis of human strongyloidiasis, and to identify their immunodominant
molecules through Western Blotting technique. Serum samples obtained from
patients with strongyloidiasis, or other helminthiasis, and healthy adults were
analyzed by enzyme-linked immunosorbent assay (ELISA). The crude antigenic
extract of S. stercoralis and fractions with molecular weight higher and lower than
100 kDa showed 90%, 90% and 84% sensitivity, and 95%, 98% and 95% specificity,
respectively. The crude antigenic extract of S. venezuelensis and fractions with
molecular weight higher and lower than 100 kDa showed 76%, 82% and 75%
sensitivity, and 43%, 93% and 64% specificity, respectively. The results reached
suggest that the fraction higher than 100 kDa concentrates immunodiminant
molecules and its presentation as lower than 100 kDa on Western Blotting suggests
that they’re organized in protein complexes dismantled by the desnaturation process
realized before the eletroforesis
