Evaluation of enzyme-linked immunosorbent assay for immunodiagnosis of clonorchiasis

Two groups of patients with parasitologically proved clonorchiasis were recruited from among staff and workers of China Petroleum Company at Miao-Li county. There were 86 patients in the pre-treatment group and 143 patients in post-treatment. The latter were defined as those treated for 18 months after a daily dosage of 3 X 25 mg/kg BW/day of praziquantel. Indirect ELISA was performed to detect the serum antibody against Clonorchis sinensis with extracted crude antigen of adult worms obtained from the bile duct of cats. Direct smears of stool for Clonorchis ova were checked concomitantly. Results revealed significant decrease of optical density ratio between pre- and post-treatment groups. Positive ELISA was detected in 79 pre-treatment group patients (91.8%) and in 28 patients (20.7%) of the post-treatment group (p less than 0.01). Distribution of ELISA titers was shown in patients of post-treatment group towards negative from 400 dilution positive in pre-treatment group. One fourth of the post-treatment group patients with positive ELISA still presented Clonorchis ova in their stool. The main cause was non-compliance of medication. The study confirms the value of immunodiagnosis of C. sinensis by ELISA in the field treatment of clonorchiasis.