The potential of rapid detection for specific antibodies in diagnosing sparganosis using plerocercoid soluble antigen

Objective To evaluate the potential of rapid detection for antibodies using plerocercoid soluble antigen(PSA) in diagnosing sparganosis.Methods Plerocercoids mansoni was collected from naturally infected frogs.Each mouse was fed five living plerocercoids and sacrificed on seven weeks post-infection.Sera and plerocercoids were collected and count.Dot immunogold filtration assay(DIGFA) was developed using plerocercoid soluble antigen(PSA) as probe.Specific antibodies in sera from infected mice,healthy mice,healthy people and other parasitic patients were detected by PSA-DIGFA,respectively.PSA-ELISA was carried out in parallel with DIGFA.Results Both of DIGFA and ELISA showed sensitivity with 100% in 49 infected mice and specificity with 100% in 30 normal mice.There was no significant difference among antibody levels of infected mice with different burden of plerocercoid(P0.05).The levels of antibodies in sera of infected mice were much higher than that of healthy mice(P0.01).All 100 healthy persons showed negative while 42.5%(17/40) cases of cysticercosis,10.0%(2/20) cases of echinococcosis,20.0%(5/25) cases of trichinosis,80.0%(8/10) cases of paragonimiasis,and 8.0%(2/25) cases of clonorchiasis were positive,respectively. Conclusion PSA-DIGFA showed high sensitivity and specificity in detecting specific antibodies in sera from infected mice.However,there were high cross-reactions with antibodies in sera from other patients.One worm burden could induce high levels of antibodies.The results of DIGFA were similar to those of routine ELISA,but the former was more handy and rapid without any specific instrumentation.DIGFA is a potential field-applicable immunoassay for diagnosis and epidemiological investigation of sparganosis if PSA could be purified to reduce the cross-reaction.