health

Filariasis is caused by different species of microscopic parasitic roundworms
that are passed to people through the bites of insects, most commonly
mosquitoes. Several strains of these worms, known as filariae (fih-LAIRe-
e), can infect humans, including Wuchereria bancrofti (voo-ker-E-re-ah
ban-CROFT-e). There are also different types of filariasis itself, including
cutaneous or skin-related, body cavity, and lymphatic infections. In the
cutaneous disease, the worms live in the layers of the skin; in body cavity
filiariasis, they inhabit certain body openings and surrounding tissue; and
in the lymphatic form of infection, they invade the vessels of the lymphatic
system and the lymph nodes.
Lymphatic filariasis, which can progress to a condition called elephantiasis,
is the most serious form of the disease. It begins when an
infected female mosquito injects worm larvae into a person’s blood while
feeding. The larvae travel to the lymphatic vessels, where they grow into
adult worms. As adults, the worms can survive and reproduce for up to
seven years. The gradual buildup of worms in the vessels hinders the
lymphatic system’s ability to fight infection and causes lymph fluid to
collect—typically in the arms, legs, breasts, and male genitals—leading to
swelling and disfigurement.