An IFAT cercarial slide antigen preparation for schistosomiasis.

A modified technique for the preparation of a cercarial microscopic slide antigen for use in IFAT, that could be stored at -20 degrees C for 6 months is described. Cercariae were deposited by cooling, fixed in 0.5% buffered formaline, mixed with 7% egg albumin, dropped on slides and dried. Before use, antigen was post-fixed in absolute methyl alcohol. Evans blue was used as a counterstain. The antigen was evaluated with known human positive and negative sera, also with sera from normal individuals and others residing in endemic areas and exposed to infections with schistosomiasis; as well as with sera of patients with other helminthic infections (strongyloidiasis, ankylostomiasis, ascariasis and microfilariasis). It indicated a sensitivity of 83% and a specificity of 61.5%.