Applicability of the Filter Paper Technique for Detection of Antifilarial IgG(4) Antibodies Using the Bm14 Filariasis CELISA

Abstract

Demonstration of successful elimination of lymphatic filariasis (LF) in endemic countries requires sensitive diagnostics for accurate definitions of endpoints and future surveillance. There has been interest in complementing available diagnostics with antibody serology testing in children, since negative serology would correspond with cessation of LF transmission. The Filariasis CELISA detects antifilarial IgG(4) and has favourable results with serum samples but field application requires an easier sampling method. Ninety-four paired plasma and filter paper samples were assayed with promising results. The filter paper method resulted in a sensitivity of 92% and a specificity of 77% when compared to the paired plasma. One hundred and one filter paper samples were assessed for storage effects. Following 10-month storage at -20( degrees )C there was a significant reduction in reactivity (P < .001). Overall the results indicated that filter paper sampling would be a favourable sensitive and specific alternative for blood collection in surveys.

Figure 1

Reactivity of eluates from 45 individuals living in a nonendemic LF area. All of the samples had OD absorbance values lower than the positive cut-off  value of  0.400 and were all considered nonreactive. The average OD absorbance value was 0.08.