Epidemiologic application of circulating antigen detection in a recent Schistosoma mansoni focus in northern Senegal.
Quantitative enzyme-linked immunosorbent assays (ELISAs) for the detection of circulating anodic antigen (CAA) and circulating cathodic antigen (CCA) in serum and urine were applied as an epidemiologic tool in a recent, intense focus of Schistosoma mansoni in Senegal. Both CAA and CCA in serum and CCA in urine were found in 94%, 83%, and 95%, respectively, of the population, of which 91% were positive on stool examination. Circulating antigens were also detectable in sera and urines of most egg-negative individuals. The sensitivities of the urine CCA and serum CAA ELISA were substantially higher than that of a single egg count, and increased with egg output. The CAA and CCA levels correlated well with egg counts and with each other. The age-related evolution of antigen levels followed a similar pattern as egg counts, providing supplementary evidence for a genuine reduction of worm burdens in adults in spite of the supposed absence of acquired immunity in this recently exposed community. The antigen:egg ratios decreased in adults, suggesting lower worm fecundity in children. This would be compatible with a density-dependent reduction of fecundity, but not with anti-fecundity immunity in adults that perhaps has not yet developed in this new focus.
Polman
K
K
Department of Parasitology, Medical Faculty, University of Leiden, The Netherlands.
Stelma
F F
FF
Gryseels
B
B
Van Dam
G J
GJ
Talla
I
I
Niang
M
M
Van Lieshout
L
L
Deelder
A M
AM
D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000947:Antigens, Helminth / Q000097:blood* / Q000652:urine*; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000469:parasitology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010270:Parasite Egg Count; D015995:Prevalence; D012550:Schistosoma mansoni / Q000276:immunology*; D012555:Schistosomiasis mansoni / Q000097:blood / Q000453:epidemiology* / Q000652:urine; D012675:Senegal / Q000453:epidemiology; D012680:Sensitivity and Specificity; D016036:Seroepidemiologic Studies
D000947:Antigens, Helminth