Objectiv To evaluate the usefulness of dot immuno-gold filtration assay(DIGFA) for the diagnosis of Paragonimus infection.Methods During 2003 to 2006,72 cases suspected of paragonimiasis in Zhejiang Province were examined with DIGFA for rapid detection of specific antibodies against Paragonimus(Pw-DIGFA).The diagnosis was primarily established with the presence of antibodies,experience of ingesting raw freshwater crabs or crayfishes and clinical presentations.The cases were treated with praziquantel and followed-up at 3 and/or 6 months post-treatment.Antibody level in patients(pre-and post-treatment) were detected in parallel and analyzed comparatively by Pw-DIGFA and ELISA.Results The result of detection by Pw-DIGFA was in agreement with that of ELISA.28 of 72 cases were antibody positive and 44 cases were negative.Among the 28 positives,26 cases had a history of eating raw freshwater crab or crayfishes and the other 2 cases drank freshwater from brook before.21 cases showed paragonimiasis-related clinical symptoms such as low-grade fever,cough,or changes in image examination,while the other 7 cases showed only eosinophilia in peripheral blood(15%-70%).The mean absorbance values(A450) of positive sera,negative sera and normal sera tested by ELISA were 1.7361,0.2973 and 0.2657 respectively.There was significant difference between the positive cases and the negative cases(t=12.047,P0.05).At 3 month post-treatment,serum antibody in 5 cases whose clinical symptoms and physical signs relieved or disappeared decreased 2-5 titers and that of one case who relapsed with new signs increased by one titer.In Pw-DIGFA,the dot color of 5 cured cases showed a little weaker than that of pre-treatment and the relapsed case displayed similar response.At 6 month post-treatment,7 sera of clinically cured cases showed significantly weaker response than that of pre-treatment.The antibodies of those sera dropped 3-6 titers.Conclusion Pw-DIGFA is of supplementary value for clinical diagnosis of paragonimiasis.Antibody detection by pre-and post-treatment using Pw-DIGFA shows potential for the evaluation of therapeutic effect.

A total number of 2221sera collected from different kinds of subjects , i.e.patients with various stages of schistosomiasis. normal individuals, persons with other parasitic diseases or non-parasitic diseases, were detected with Dot Immunogold Filtration Assay (DIGFA) using anti-SVLBP IgG as capturig antibody. Positive rate of 70 sera from patients with acute schistosomiasis was 100%, and that of 307 sera with chronic schistosomiasis was 68.4% .None of 200 sera from normal individuals showed false positive reaction. No obvious cross reaction was found in sera from other parasitic/non-parasitic diseases except sera from patients with paragonimiasis.2 batches of sera were detected with DIGFA by single-blindness method. Results showed that sensitivities to chronic schistosomiasis were 69.4% and 68.9%, and 100% to acute schistosomiasis while specificities were 98.9%-99% .508 samples from residents in endemic areas were tested with DIGFA and Kato-Katz. Positive rate of circulating arrtigen was 20.9% with DIGFA while 65 samples were positive with stool examination.46 samples were positive both by DIGFA and by Kato-katz.The coincidental rate was 70.8% .These results indicated that DIGFA showed sensitive and specific in the detection of circulating antigen. It will be useful in mass application and vahuable in epidemiological stuvey.

To determine the diagnostic value as well as the evaluation value in therapy, the specific IgM and IgG anti-bodies of the infected and treated rabbits were detected using soluble egg antigen(SEA) and adult worm antigen(AWA) by ELISA. By using SEA to detect the IgM antibodies, the serum antibody level rapidly dropped 7 weeks after infection even without treatment, and those of IgM in sera detected by AWA rose early than IgG detected by SEA. After 5 month treatment, IgM detected by AWA and IgG detected by SEA were still positive. From these observations, it is evident that SEA is a better antigen to detect specific IgG in the diagnosis of schistosomiasis, AWA is a better one for early diagnosis. The use of AWA as antigen to detect IgM showed high diagnostic value both in acute and chronic schistosomiasis. However, detection of the IgM/ IgG in ELISA using SEA and AWA could not evaluate the therapeutic effect well.

0.05). Among 36 sera collected at 12 months post-treatment, the antibody negative conversion rates were 80.6% (29/36) and 58.3% (21/36), there was a significant difference between the two assays (P