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How is lymphatic filariasis transmitted?

Lymphatic filariasis results from parasitic worms that are transmitted by the bites of mosquitoes in tropical and subtropical regions of the world. Several species of mosquitoes can transmit the disease, but in rural Africa, the Anopheles mosquito is the primary carrier for both lymphatic filariasis and malaria.
 
An infected mosquito deposits microscopic larvae while biting a person, and the larvae migrate to the human lymph system, where they mature into adult worms. 

In the lymphatic system, adult worms mate and form nests, which cause blockages resulting in fluid collection, swelling, and fever. Adult worms live for about five to seven years. Female worms produce millions of microfilariae (baby worms) that swarm in the blood at night when mosquitoes bite, continuing the cycle.

When a mosquito bites a person who has lymphatic filariasis, it ingests the microfilariae and becomes infected.  While inside the mosquito, the microfilariae develop over a period of a week into infectious larvae, and the cycle continues.


While infections are contracted throughout life, most individuals can remain asymptomatic for years, with symptoms emerging during adolescence and adulthood.