Application of thin layer immunoassay (TIA) as a serodiagnostic tool in schistosomiasis. A preliminary report

Thin layer immunoassay (TIA) is a recently developed simple serological technique which, in a preliminary study, has been applied to the serodiagnosis of schistosomiasis. 64 of a total of 69 sera from patients with schistosomiasis were positive in TIA when a Schistosoma mansoni worm antigen preparation was used as coating material. A trial of the diagnostic specificity of the assay was made by cross-testing sera from patients with different parasitic diseases, using TIA plates coated with extracts from the relevant parasites. All sera from patients with filariasis, fascioliasis and echinococcosis were positive in homologous TIA systems. In heterologous systems, cross-reactivity was noted for some sera in all groups except fascioliasis. The largest proportion of cross-reacting sera was registered in the echinococcosis group. It is suggested that, after further evaluation, the TIA technique might supplement or be used as an alternative to other serological tests already in use for the diagnosis of schistosomiasis. In favour of the TIA technique are its simplicity and its low cost.