Cross-reactions in immunodiagnosis of patients infected with Schistosoma, Fasciola and Heterophyes using ELISA.

Cross-reactions in immunodiagnosis using schistosomal soluble egg antigen (SEA) and Fasciola adult worm antigen in cases with fascioliasis, heterophyiasis and schistosomiasis were studied by ELISA techniques. False positive reactions occurred in 10% of cases with fascioliasis and heterophyiasis respectively when using schistosomal SEA. Using Fasciola crude antigen, false positive reaction occurred in 25% of cases with schistosomiasis and 35% with heterophyiasis. The specificity of SEA in heterologous cases was 87% while that of Fasciola antigen was 70%. This difference was found to be statistically significant.