Serologic techniques provide an alternative to microscopic detection of microfilariae for the diagnosis of lymphatic filariasis. Patients with active filarial infection typically have elevated levels of antifilarial IgG4 in the blood and these can be detected using routine assays. The development of an immunochromatographic card test (ICT) with high sensitivity and specificity for detecting W. bancrofti infection has simplified diagnosis, and test kits are commercially available. The test requires 100 μl of fingerprick blood drawn at any time, day or night.