A SIMPLE TECHNIQUE TO PRETREAT URINE AND SERUM SAMPLES FOR QUANTITATION OF SCHISTOSOME CIRCULATING ANODIC AND CATHODIC ANTIGEN

For the detection of the circulating schistosome antigens CAA (circula ting anodic antigen) and CCA (circulating cathodic antigen) in serum a nd urine samples of Schistosoma infected individuals, pretreatment of samples with trichloroacetic acid (TCA) is a standard procedure. In th e present study several methods were evaluated in order to develop a m ore simple and rapid technique than the - especially for pretreatment of urine samples - laborious TCA technique. Optimal results were obtai ned with a method in which serum or urine samples were pretreated by a heat-incubation step (70 degrees C, 30 min) in an alkaline buffer (pH 9.6). In a comparison of the new technique with the TCA pretreatment, serum and urine samples of S. mansoni infected individuals from Zaire (n = 80) and of uninfected controls from The Netherlands (n = 208) we re pretreated and assayed for CAA and CCA. Both pretreatment technique s showed similar sensitivities and specificities for CAA and CCA in se rum, and CCA in urine. However, for the determination of CAA in urine the new technique performed significantly better, resulting in an incr ease of the sensitivity from 32 to 70% (titre determination).