Using qualitative ICT
Filariasis and quantitative Og4C3 ELISA, we assessed a long-term macrofilaricidal effect of two-year biannual mass treatments with
a 300 mg oral-dose FILADEC
tablet, a reformulation of 6 mg/kg
diethylcarbamazine (DEC), on clearance of the Wuchereria bancrofti adult worm circulating filarial
antigens (CFA) in Myanmar migrants, at risk of emergence of imported
bancroftian filariasis in Southern Thailand. Of the 34 antigenemic Myanmar index cases of varying initial CFA levels, who were initially screened out with the ICT
Filariasis, 13 index cases were follow-up treated and monitored at the DEC post treatments, 6, 12, and 18 months. At the 18-month post treatment, residual antigenemias (%) in 4 of 5 index cases (group 1) with high
antigen titers (99.7-181.6 x 10(3) AU/ml) were 54.44%, 33.58%, 27.43%, and 9.97%. Significant decreases of the CFA levels in only 3 out of 5 index cases were affected by the response to DEC treatments (p < 0.007). The treatment effects on clearance of the CFA in 8 index cases (group II) with low
antigen titers (15.4-37.2 x 10(3) AU/ml) were shown for at least 6 months post DEC treatment and hence had 100% efficacy in the first 6 months of the first year of year round treatment. Group I, was more likely to show an increase of the DEC efficacy after the first 6 months of the second year round treatment, but there was no statistically significant difference (p = 0.063). We reemphasized that, for use in the national program to eliminate
lymphatic filariasis (PELF) in Thailand, such a
DEC regimen had a macrofilaricidal effect on antigenemia clearance, and confirmed its value in evaluating response to the treatment and monitoring the long-term efficacy of the
DEC regimen in W. bancrofti adult worm burden reductions in Myanmar migrants on a wide scale.