This is a case of filariasis causing elephantiasis. Three filarial worms can produce this condition. Infection results from an insect bite. Adult worms develop within the human host and microfilariae are transmitted back to biting insects. A severe fibrotic reaction obstructs lymphatic channels. This filariae are destroyed with antihelminthic treatment but the oedema is not reversed. There is a non-filarial form of elephantiasis possibly caused by silicates being absorbed from the soil to the feet.