Immunodiagnosis of filariasis

The sensitivity and specificity of the enzyme-linked immunosorbent assay (ELISA), the indirect haemagglutination (IHA) test and the counter-current immuno-electrophoresis test (CIEP) were assessed in the diagnosis of filariasis. Positive reactions were observed in 91% and 86% of cases by ELISA and IHA respectively. CIEP detected only 31.5% of cases. Cross-reaction due to intestinal nematodes was observed in 80% of cases by both ELISA and IHA whereas with CIEP cross-reaction was observed in 10% of cases. The microfilaria count was inversely proportional to the antibody titre among asymptomatic carriers. ELISA was the most sensitive test, followed by IHA and then CIEP. CIEP, though it detected only a small number of cases, was observed to be the most specific.