EJMS

Abstract

Lymphatic filariasis is a painful and profoundly disfiguring disease. Infection is usually acquired in childhood but its visible manifestations occur later in life, causing temporary or permanent disability. The importance of developing effective assays to diagnose, monitor and evaluate human lymphatic filariasis has been emphasized by the WHO. This study aimed to assess the use of serological methods to detect antifilarial antibodies (IgM, IgG, IgG4) versus direct detection of microfilaria in peripheral blood smears for diagnosis of bancroftian filariasis in endemic areas. One hundred individuals were enrolled in this study: 40 were chronic lymphoedema patients suffering from Wuchereria bancrofti infection obtained from endemic areas for W.bancrofti, 40 individuals apparently clinically free from filariasis, with life long residence in endemic areas and in close contact with infected cases (Endemic normals) and 20 individuals free from filariasis grouped as normal healthy control group. Each donor was examined by thin and thick blood films for detection of microfilariae. OnSite Filariasis IgG/IgM Rapid-Cassette format Test was used for detection of IgM and IgG anti-filarial antibodies specific for W.bancrofti and Enzyme Linked Immuno-Sorbent Assay (ELISA) for detection of circulating IgG4 anti- W.bancrofti antibodies in serum samples. It was found that no microfilariae were detected by thin or thick blood films among studied groups and the IgG rapid strip test showed higher sensitivity and specificity among the chronic (lymphoedema) cases.The IgM onsite test showed high sensitivity and specificity among the endemic normal individuals ,although the IgG4 ELISA test proved to be more sensitive in identifying actively infected individuals and does not exhibit day-night variation. In conclusion, the anti-filarial IgG4 test could be used for proper prevalence survey prior to implementation of chemotherapy program and for determining the efficacy of the filariasis control program.