Wuchereria bancrofti and Wuchereria malayi are the filarial worms which causes a slowly developing chronic inflammation of the organs in which they live for many years.

Usually they live in lymphatic vessels of lower limbs and obstruct the flow of lymph resulting in swelling of lower limbs which resembles the feet of an elephant. Thus it is also known as Elephantiasis.

$\rightarrow$ The genital organs are also affected, resulting in gross deformities.

The pathogens are transmitted to a healthy person through bite of female mosquito vectors, eg., Culex, Aedes, etc.