Inter-test comparison between filter paper absorbed blood eluate and serum for malaria serology by enzyme immunoassay: An operational feasibility

Antimalarial IgG and IgM were detected by enzyme immunoassay in finger-stick blood samples collected in capillary tubes and also spotted onto Whatman filter paper. Assay was performed in 92 blood samples obtained from 53 falciparum malaria patients, representing 23 fever cases (malaria negative) and 16 healthy individuals. A simple indirect ELISA was done using Plasmodium falciparum lysate and MSPI 19 peptide as antigens. Total IgG and IgM contents were also estimated in individual sera and filter paper eluate by single radial immunodiffusion (SRID). Assay results of both serum and filter paper eluates were compared. The sensitivity and specificity of the assays for IgG measurement were comparable between serum and filter paper eluates (P < 0.001), whereas, in case of IgM, detection level was poor in filter paper eluates as observed by ELISA and SRID. The filter paper eluates may serve the purpose of antigen-specific IgG detection in seroepidemiological surveys.