In India diurnally subperiodic filariasis (DspWB) is prevalent only in the Nicobar district of Andaman and Nicobar Islands. Studies undertaken at different points of time indicate that this form of filariasis is restricted to a small region in Nancowry group of islands where it is transmitted by mosquito Downsiomyia nivea, a day biting mosquito.

The archipelago of the Andaman and Nicobar islands consists of 572 islands; 35 are known to be inhabited. These are home to five tribes. The Jarawas, Sentinelese and Onges are Negrito tribes. The Andamanese have ceased to be a tribe and a pure-blood Andamanese is a rarity. The remaining two are mongoloid tribes, the Nicobarese and the Shompen.