Elimination of diurnally sub-periodic Wuchereria bancrofti in Andaman and Nicobar Islands, India, using mass DEC-fortified salt as a supplementary intervention to MDA.

Feasibility of implementing a DEC-fortified (DEC at 0.2% w/w and iodine) salt strategy to hasten elimination of diurnally sub-periodic Wuchereria bancrofti (DspWB) from the lone foci in Nancowry islands, Nicobar district, India, was assessed. This is a two-arm community-based study: one arm (12 villages, population 2936) received double fortified salt along with annual mass drug administration (MDA) of DEC plus albendazole (DEC-salt+MDA-arm), and another (14 villages; population 4840) received MDA under the National Filaria Elimination Programme. DEC salt was distributed on camp mode supplemented by door delivery. Monthly survey was carried out in fixed and random households to assess the coverage, usage of DEC salt and DEC content. The impact on prevalence of mf at community level and antigenaemia among children was assessed. A total of 21 metric tonnes of free-flow DEC salt manufactured by Tamil Nadu Salt Corporation, India, was distributed for 1 year. In the DEC-salt+MDA-arm, > 90% of the households received and used the DEC salt. DEC was within therapeutic range (0.2-0.32% w/w) in the samples collected from kitchens. Community mf prevalence reduced from 2.27 to 0.14% in the DEC-salt-arm (< 1% in all the villages) and 1.26 to 0.74% (> 1% in 4 out of 14 villages) in the MDA-arm. Ag prevalence reduced to zero from 1.0 (DEC-salt+MDA-arm) and 6.3% (MDA-arm) in 2-3 years old, 1.2 and 3.6% from 2.9 in the DEC-salt-arm and 4.5% in the MDA-arm among 6-7 years old. It was feasible to deliver DEC-fortified salt covering > 90% of the households with compliance reaching the elimination target in the islands.