Quantitative assessment of circulating antigens in human lymphatic filariasis: a field evaluation of monoclonal antibody-based ELISA using blood collected on filter strips

OBJECTIVE To quantify circulating antigens in individuals with lymphatic filariasis by means of an ELISA using blood on filter strips. METHOD Circulating antigens in filarial patients and normal individuals living in an area endemic for W. bancrofti infection in Madras, India were estimated using a monoclonal antibody-based ELISA. RESULTS All microfilaraemics showed positivity to circulating antigens whereas people with chronic pathology and 80% of the endemic normals tested negative. The antigen levels in the blood collected in the night and during day time showed positivity and there was no difference in the antigen concentration. The results of the antigen levels collected onto filter strips correlated with their corresponding plasma antigen levels (r = 0.83). In microfilaraemics, DEC treatment did not alter the levels of circulating antigens for up to one month. CONCLUSIONS We conclude that this monoclonal antibody-based ELISA using filter strips may be used in day time and replace the existing routine night blood surveys in our endemic area in India.