The immunofluorescence antibody test (IFAT) for the diagnosis of schistosomiasis used in a non-endemic area.

The aim of this study was to evaluate an immunofluorescence antibody test (IFAT) for diagnosis of schistosomiasis in nonimmune travelers and immigrants from endemic areas. 65 patients (48 Danes and 17 immigrants) with schistosomiasis were included. The diagnosis of schistosomiasis was based on the presence of schistosome eggs in feces urine sperm rectal or bladder biopsies and/or the presence of specific antibodies determined by the serological IFAT. Egg excretion was detected using conventional methods and the IFAT performed on whole Schistosoma mansoni schistosomula worms harvested after 8 weeks from mice. Two patterns of immunofluorescence were observed: Fluorescence in the gut of the schistosome called Gut Associated Antigen (GAA) and fluorescence of the surface of the schistosomula called Membrane Bound Antigen (MBA) . Eggs were found in 44% of the Danish patients and in 76% of immigrants. The diagnosis was based on a positive IFAT in 48% of the patients. In patients from nonendemic areas the finding of the antibodies against GAA was diagnostic while optimal sensitivity in the immigrants was reached by measuring antibodies against both GAA and MBA. In patients from nonendemic areas GAA is a sensitive marker of acute infection with schistosomiasis. In patients from endemic areas the demonstration of both GAA and MBA is necessary to properly identify long-lasting nonacute infections. Egg-detection and/or measurement of circulating anodic antigen and circulating cathodic antigen remain the methods of choice to monitor treatment as the immunofluorescence assay may remain positive for several years after treatment. (authors)