Lymphatic filariasis, considered globally as a Neglected Tropical Disease, is a parasitic disease caused by microscopic, thread-like worms. The adult worms only live in the human lymph system. The lymph system maintains the body's fluid balance and fights infections. Lymphatic filariasis is spread from person to person by mosquitoes.

People with the disease can suffer from lymphedema and elephantiasis and in men, swelling of the scrotum, called hydrocele. Lymphatic filariasis is a leading cause of permanent disability worldwide. Communities frequently shun and reject women and men disfigured by the disease. Affected people frequently are unable to work because of their disability, and this harms their families and their communities.

The elimination of lymphatic filariasis in the Americas is one of CDC's Winnable Battles.

Image: Left: Microfilaria of Wuchereria bancrofti in thick blood smear stained with Giemsa. Right: Microfilaria of Brugia malayi in a thick blood smear, stained with Giemsa. Center: Photograph of a female Aedes aegypti mosquito as she was in the process of obtaining a "blood meal." Laboratory strains of Aedes aegypti can be infected with Brugia. Credit: DPDx, PHIL