New Approaches with Different Types of Circulating Cathodic Antigen for the Diagnosis of Patients with Low Schistosoma mansoni Load

BACKGROUND Schistosomiasis mansoni is a debilitating and sometimes fatal disease. Accurate diagnosis plays a key role in patient management and infection control. However, currently available parasitological methods are laborious and lack sensitivity. The selection of target antigen candidates has turned out to be a promising tool for the development of more sensitive diagnostic methods. In our previous investigations, the use of crude antigens led to false-positive results. Recently, focus has been given to highly purified Schistosoma mansoni antigens, especially to circulating antigens. METHOD Thus, our main goal was to test different types of circulating cathodic antigen glycoprotein (CCA), as "crude antigen," the protein chain of recombinant CCA and two individual peptides. These schistosome proteins/peptides were tested in a new diagnostic method employing immunomagnetic separation based on the improvement of antigen-antibody binding. PRINCIPAL FINDINGS Use of recombinant CCA as a diagnostic antigen allowed us to develop a diagnostic assay with high sensitivity and specificity with no false-negative results. Interestingly, the "crude antigen" worked as a good marker for control of cure after praziquantel treatment. CONCLUSIONS/SIGNIFICANCE Our new diagnostic method was superior to enzyme-linked immunosorbent assay in diagnosing low endemicity patients.