Application of immunodiagnostic assays: Detection of antibodies and circulating antigens in human schistosomiasis and correlation with clinical findings

In an initial cross-sectional survey, serum, urine, and stool samples were collected from 370 participants representing about 10% of the population (n = 4,438) in Behbeet village, 50 km south of Cairo, Egypt, an area well kno wn to be endemic solely for Schistosoma haematobium. Diagnosis was approach ed in two parallel ways. The first approach, which simulated actual conditi ons in many endemic areas in Egypt, was based on physical examination and u rine and stool microscopic analysis. The second approach was based on two a dvanced immunodiagnostic assay systems. One system detected antibodies to s pecies-specific microsomal antigens, the other detected circulating schisto somal antigens. Microsomal antigens from S. haematobium and S. mansoni were used to detect antibodies in the Falcon assay screening test (FAST(R))-ELI SA and the enzyme-linked immunoelectrotransfer blot (EITB). Circulating ano dic antigen (CAA) and circulating cathodic antigen (CCA) were quantified in serum and urine samples in a sandwich ELISA using monoclonal antibodies. P arasitologically, the prevalence of S, haemntobium was 7.01% in females and 25.82% in males, giving an overall prevalence of 15.8%. The combination of urine CCA and serum CAA for detecting circulating antigens and the combina tion of the S. haematobium adult worm microsomal antigens (HAMA) FAST-ELISA and the HAMA EITB for detecting antibodies significantly improved the sens itivity of detecting S. haematobium circulating antigens and antibodies. Al so, including a medical examination as an integral part of field studies an d correlating immunodiagnostic results with other clinical and investigatio nal data allowed us to calculate an accurate estimation of S. haematobium p revalence in this area of low endemicity.