Visual detection of filaria-specific IgG4 in urine using red-colored high density latex beads

The use of urine for the immunodiagnosis of lymphatic filariasis has a definite advantage: the sample collection is not invasive and thus well accepted by people. Urine-based ELISA to detect filaria-specific IgG4 has been used successfully. However, ELISA requires equipment such as a microplate reader, which is often not available in most endemic areas. We have developed a new visual immunodiagnosis that detects urinary IgG4 using red-colored latex beads (bead test). The sensitivity was 87.2% when ICT antigen test positive people were regarded as the standard (136/156), and the specificity was 97.2% with the non-endemic people in Japan and Bangladesh, and the urine ELISA negatives in Sri Lanka (1264/1300). In a prevalence study, the bead test could detect filarial infection more effectively than ICT test among young children in Sri Lanka, indicating the usefulness of the visual test in epidemiological studies.

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► A diagnostic tool for lymphatic filariasis was developed using colored latex beads.
► The tool detects antigen specific IgG4 in urine and the results are visible.
► Its sensitivity and specificity are 87.2% and 97.2%, respectively.
► The tool is useful to evaluate control programs during and after MDAs.