Detection of the circulating antigens CAA and CCA in a group of Dutch travellers with acute schistosomiasis.

Abstract

Detection of circulating anodic antigen (CAA) and circulating cathodic antigen (CCA) in serum and urine is a highly specific and sensitive alternative for the diagnosis of schistosome infections in endemic areas. However, it is not known how soon after the onset of infection these antigens can be detected in humans. Neither has there been much research on the detection of these antigens in individuals normally living in non-endemic areas. We studied the kinetics of CAA and CCA in serum and urine of a group of 28 Dutch tourists, shortly after accidental exposure to a Schistosoma infection during a visit to Mali. Twenty-seven were found to be positive for Schistosoma eggs and/or specific antibodies. From each individual, 1-4 serum samples were tested for circulating antigen level, 4-15 weeks after exposure, and urine samples were also tested from 22 subjects. CAA and CCA levels were quantified by monoclonal antibody-based ELISAs and TRIFMAs. In serum, 23 individuals (85%) were positive at least once for one or both antigens, but titres were generally very low. CAA and CCA could be detected 5 and 6 weeks after exposure, respectively. Urines were all found to be negative. Almost all cases were negative at 7 months' follow-up.