SERUM CIRCULATING EGG ANTIGEN LEVELS IN 2 AREAS ENDEMIC FOR SCHISTOSOMA-MANSONI

A monoclonal antibody-based enzyme-linked immunosorbent assay detectin g Schistosoma mansoni circulating soluble egg antigen (CSEA) was appli ed in epidemiological studies. The serum CSEA levels were determined f or 2 populations with a high prevalence (>95%) and high intensity of i nfection as determined by faecal egg counts. In one population (Maniem a, Zaire) transmission had been occurring for several decades, while i n the other population (Ndombo, Senegal) transmission had started only recently. CSEA could be detected in 88% and 70% of the serum samples from Maniema and Ndombo, respectively. The sensitivity of the CSEA ass ay increased with rising egg count. The age-related CSEA profiles of t he Maniema population followed a pattern similar to that of egg counts and of the adult. worm antigen CAA (circulating anodic antigen). Howe ver, the recently infected Ndombo population showed a clearly differen t profile: while the CSEA prevalence reached a peak in children and ad olescents, the mean CSEA levels did not vary significantly in the diff erent age groups. CSEA levels were significantly lower in Ndombo than in Maniema. As egg antigens in serum are thought to be in part, or eve n primarily, derived from eggs in the tissues, these findings indicate a relatively smaller tissue egg load in Ndombo than in Maniema.