Enzyme-linked immunosorbent assay using excretory/secretory and somatic antigens as a diagnostic test for human hookworm infection

Excretory/secretory (E/S) and somatic antigens prepared from third stage infective larvae of Ancylostoma duodenale were evaluated for the diagnosis of human hookworm infection by enzyme-linked immunosorbent assay (ELISA). Taking the mean absorbance plus 2 standard deviations (SD) of normal serum as the cut-off value, the positivity rates in 30 hookworm cases were 97% and 93% respectively. False positivity with E/S antigen was 8-20% in 61 control subjects; with somatic antigen it was slightly lower. In contrast, when the mean absorbance value plus 2 SD of control groups with other parasitic infections was taken as cut-off point, the positivity was 93% with E/S antigen and 43% with somatic antigen, indicating the superiority of E/S antigen. Percentage positivity declined after treatment of hookworm cases. No relationship was found between ELISA reactivity and severity of infection.