Identification of schistosomal eggs. Description of an immunological spot assay for hatch fluid antigen

A number of parasitic worms produce large numbers of eggs which may be identified by microscopy in the excretions of the host. Alternative identification methods would be useful for epidemiological purposes and this paper describes a non-microscopical method for the demonstration of schistosomal eggs, which is based on the release of soluble material from eggs during hatching in water. Substances present in hatch fluid from Schistosoma mansoni eggs were adsorbed to nitrocellulose paper and then visualized as small stained spots using horseradish peroxidase (HRP)-labeled lectins or specific antibodies. In this way the number of living eggs present in the sample could be estimated. The method may be useful as a basis for the development of diagnostic assays.