APPLICABILITY OF ELISA ON BUFFER-ELUATES OF CAPILLARY BLOOD SPOTTED ON FILTER PAPERS FOR THE DIAGNOSIS AND CLINICAL STAGING OF HUMAN SCHISTOSOMIASIS

The relative concentrations of IgM and IgG antibodies (Ab) to Schistos oma mansoni soluble egg antigen (SEA) were evaluated in paired samples of venous blood sera and buffer eluates of capillary blood drops drie d on filter papers, The samples were obtained from school children at early and chronic stages of schistosomiasis diagnosed on the basis of history, clinical symptomatology and parasitological criteria. Enzyme linked immunosorbent assay (ELISA), simultaneously performed, revealed paired samples to display comparable Ab levels in all cases. Samples from children with early schistosomiasis had specific IgM:IgG ratios g reater than 1 [optical densities (O.D.) in sera and blood eluates of 0 .77 +/- 0.32 and 0.68 +/- 0.30, respectively for IgM and 0.52 +/- 0.25 and 0.50 +/- 0.25 for IgG] This ratio, however, was less than 1 in sa mples from chronically infected children (O.D. of 0.20 +/- 0.11 and 0. 20 +/- 0.11 for IgM and 0.69 +/- 0.33 and 0.73 +/- 0.32 for IgG) The s pecific advantages of this simplified technique are the use of anti SE A Abs in fingerstick blood eluates, rather than sera of venous blood t o serologically diagnose schistosomiasis and to differentiate early fr om chronic infections particularly when used for mass screening, such as epidemiologic surveys.