Lymphatic filariasis

Diagnosis

Diagnostic tests recommended for use in the Global Programme to Eliminate Lymphatic Filariasis

Circulating microfilariae can be detected by examining thick smears (20–60 μl) of finger-prick blood. Blood must be collected at a specific time – either at night or during the day – depending on the periodicity of the microfilariae. The method is inexpensive and feasible at individual and community levels for mapping the endemicity of lymphatic filariasis and monitoring mass drug administration (MDA).

The Alere Filariasis Test Strip (FTS) is a rapid diagnostic test recommended for mapping, monitoring and transmission assessment surveys (TAS) for the qualitative detection of Wuchereria bancrofti antigen in human blood samples. The FTS has replaced the BinaxNow filariasis immunochromatographic test (ICT), which also detects the same antigen in blood samples. The Brugia Rapid point-of-care cassette test (BRT) manufactured by Reszon Diagnostics is recommended for use during TAS to detect IgG4 antibody against Brugia spp. in human blood samples.

Survey results using new test can determine the success of mass drug administration
© WHO/J. King

Other diagnostic tools

Microfilariae DNA can be detected in human blood and in mosquitoes through laboratory-based methods using PCR (Polymerase Chain Reaction). Efforts are ongoing to validate the use of new rapid diagnostic tests targeting antibodies in population-based surveys for programmatic use in post-MDA surveillance. Methods for identifying infection in mosquitoes are available and are being used in some settings as an indirect, non-invasive way to monitor the continued presence of infection in communities.

How to use FTS

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