Sandbox:Filariasis pathogenesis

Type of filariasis	Causative nematode	Vectors	Life cycle	Illustrative image	Comments
Lymphatic filariasis	Wuchereria bancrofti	Culex as C. pipiens Aedes as A. aegypti Anopheles as A. arabinensis Coquillettidia.as C. juxtamansonia	Infected mosquito bite introduces the third stage larva onto the skin and then enters to the blood through the wound. The larvae develop to adult which reside in the lymphatic vessels. Adult worm produce sheathed microfiliae that migrate to lymph and blood. They have nocturnal periodicity. Another mosquito ingests the microfiliae. The microfilariae lose their sheaths and work their way through the wall of the proventriculus and cardiac portion of the midgut to reach the thoracic muscles Microfiliae grow up inside the mosquito till third stage larvae. In another bite to a host skin the mosquito introduces the larvae onto the skin.		The difference between the nematodes causing lymphatic filariasis is in the shape and size of the worm. The Brugia worms are similar to the W. bancrofti but smaller.
	Brugia timori and Brugia malayi	Mansonia Aedes
Subcutaneous filariasis	Loa loa filaria	Chrysops C. silacea C. dimidiata	Infected fly bite introduces the third stage larva onto the skin and then enters to the blood through the wound. The larvae develop to adult which reside in the subcutaneous tissue. Adult worm produce sheathed microfilariae that are found in the blood during day and in the lungs during the non circulating phase. They have diurnal periodicity. Another fly ingests the microfiliae. After ingestion, the microfilariae lose their sheaths and migrate from the fly's midgut through the hemocoel to the thoracic muscles of the arthropod. Microfiliae grow up inside the fly till third stage larvae. The third-stage infective larvae migrate to the fly's proboscis and in another bite the cycle restarts.		Unlike Loa Loa filaria, Mansonella streptocerca and Onchocerca volvolus produce unsheathed non-periodic microfilariae. Mansonela streptocerca adults residue in the dermis. Onchocerca volvulus adults residue mainly in the subcutaneous nodules. Their microfilariae can be found in the peripheral blood, urine, and sputum but are typically found in the skin and in the lymphatics of connective tissue.
	Mansonella streptocerca	Midge (genus Culicoides)
	Onchocerca volvulus	Blackfly (genus Simulium)
Serous cavity filariasis	Mansonella ozzardi
	Mansonella perstans

Life cycles of the roundworms causing filariasis: