THE DEVELOPMENT OF COLLOID-GOLD LABELED ICT KIT FOR CLONORCHIASIS AND ITS PRELIMINARY APPLICATION IN FIELD

Objective To develop a rapid colloid-gold labeled immunological diagnosis kit for clonorchiasis, and estimate its sensitivity, specificity, and manifestation in field application. Methods The worm water-soluble antigens, secretory-excretory antigens, and recombinant antigen phosphate glyceric acid kinase (PGK) were used as diagnostic reagents. The sensitivity and specificity of these antigens were estimated in laboratory and field by ICT kits, and ICT was compared with ELISA and microscopy of eggs in stool. Results In laboratory, the positivity of IgG against Clonorchis sinensis in sera from clinically proved clonorchiasis patients was all 100% by 3 ICT kits, the natural antigens showed some cross-reaction with sera from chronic schistosomiasis patients and no cross-reaction with sera from Cysticercosis, Echinococcosis and Toxoplasmosis patients. The recombinant antigen PGK had no cross-reaction with all these sera. In field test, the accordance of sera and saliva assay by ICT was 92.31%, and that of ICT and ELISA was 81.54%; microscopy found C. sinensis eggs in stool samples of 4 persons whose sera were strongly positive for specific IgG by ICT and ELISA. 1 of the other 5 persons negative for eggs was positive for serum IgG by ICT and ELISA, another was only slightly positive for sera IgG by ELISA. Conclusion The way of ICT detecting IgG for diagnosis of clonorchiasis, particularly the no-injury saliva detection, was simple, rapid, accurate, and safe, superior to sera ELISA and microscopy for eggs in stool, suitable for clinical diagnosis and large scale epidemical investigation in field.