Filarial Nematodes They are characterized by the following:

1 - They inhabit tissues.
2 -They need an arthropod for their transmission.
3 -  The female is gives birth to elongatedembryos (containing no organs) called microfilaria. Microfilariae may be sheathed or
unsheathed.
4 - Male is about 2-4 cm and the female is double its size except female Onchocerca (25-50 cm).

Wuchereria bancrofti

Distribution : Tropical and subtropical areas e.g. Central and South America, coastal Asia
and Africa. In Egypt It is found in the Nile Delta particularly on the eastern side of the Damietta branch, in Qalubiya, Sharkia and Dakahlia Governorates. Focal distribution is present in Giza, Cairo and Assiut.
Habitat : Adults inhabit lymphatic tissues of
lower limbs and external genitalia. Microfilariae are found in lungs by day and in blood by night.
DH : Man is the only definitive host.
Vector : Female Culex mosquito.source : http://communitypharmacyotc.blogspot.com/2014/04/filarial-nematodes-wuchereria-bancrofti.html#.U0Frp6MQ_Dc