Filarial antibody detection in suspected occult filariasis in children in an endemic area.

A study was conducted in filarial endemic area for diagnosis of occult filariasis in various clinical conditions in children. Thirty-five age- and sex-matched controls (endemic-15, non-endemic-10, disease control-10), 16 classical lymphatic filariasis, and 92 occult filariasis (clinical conditions which fall in the spectrum of occult filariasis and suspected to be filarial), were subjected to peripheral night blood smear examination for microfilaria (mf) and stick ELISA test using mf ES antigen for filarial antibodies. In the control group none showed mf and only 3 per cent (1/35) among endemic control were positive for filarial antibodies. In classical filariasis 1 per cent (2/16) showed mf and 94 per cent (15/16) had filarial antibodies. In suspected occult filariasis 1 per cent (one case of arthritis) showed mf and 62 per cent (57/92) showed filarial antibodies. These consisted of tropical pulmonary eosinophilia 63 per cent (15/24), arthritis where no cause could be ascertained on investigation 64 per cent (27/42), nephrotic syndrome 69 per cent (11/16), acute glomerulonephritis with ASO < 200 units 38 per cent (3/8), and cardiomyopathy 50 per cent (1/2). Correlation with age showed that 80 per cent (4/5) of cases of arthritis seen in 0-4 years of age group and 82 per cent (11/9) of nephrotic syndrome in the 10-14 years of age group were positive for filarial antibody. Arthritis due to other causes and minimal change nephrotic syndrome are uncommon in these respective age groups. It is concluded that the role of filariasis in endemic areas in these disease states cannot be denied and needs to be studied further.