Evaluation of ELISA for the diagnosis of paragonimiasis westermani

Possible applicability of an enzyme-linked immunosorbent assay (ELISA) for the diagnosis of paragonimiasis westermani was examined using crude extract of adult Paragonimus westermani (Pw) as the test antigen. The mean ELISA values of the sera from Pw egg-positive cases and from clinically suspected cases were more than 22 times higher than that of the healthy control. No, or only marginal, cross-reactivity was observed against Pw antigen using sera from patients with various parasitic diseases other than paragonimiasis, except that from schistosomiasis and clonorchiasis cases. When serum samples from the endemic area were tested by ELISA and double diffusion (DD), sera from skin test (ST)-positive and DD-positive cases were all positive with ELISA, whereas approximately 19% of ST-positive but DD-negative cases were positive for ELISA. Diagnosis by ELISA values correlated well with, and seemed to be more sensitive than, that by DD test. In some definite paragonimiasis cases, the ELISA value was markedly reduced after drug-treatment with bithionol. These results suggest that ELISA is useful not only in mass screening but also in the evaluation of the efficacy of drug treatment in paragonimiasis.