A SEDIMENTATION-SELECTIVE FILTRATION METHOD FOR THE DIAGNOSIS OF LIGHT INFECTIONS WITH SCHISTOSOMA-MANSONI

An epidemiological survey for infection with Schistosoma mansoni was c arried out in the community of Catharina Sophia in northern Surinam. T he merits of a more sensitive diagnostic system, the Sedimentation-Sel ective-Sieving (SSF) method, were evaluated; the results were compared with those obtained with the standard Kato-Katz thick smear technique . Examination of a duplicate Kato smear (2 x 25 mg) resulted in a prev alence of 22% while the real prevalence was shown to be more than 42%. The SSF procedure was shown to have a comparatively high sensitivity although the egg counts per gram (calculated on the basis of examining samples of 2-3 g) were considerably lower than those derived from Kat o smears. The implications for epidemiological surveillance of communi ties with excretion of low numbers of S. mansoni eggs are discussed an d the observations are compared with those one might expect on the bas is of mathematical modelling (De Vlas et al., 1992).