Lymphatic filariasis is a parasitic disease caused by microscopic, thread-like worms.
The adult worms only live in the human lymph system. The lymph system maintains your body's fluid balance and fights infections. Lymphatic filariasis affects over 120 million people in 73 countries throughout the tropics and sub-tropics of Asia, Africa, the Western Pacific, and parts of Central and South America. You cannot get the worms in the United States. The disease spreads from person to person by mosquito bites.