Filiariasis is a group of tropical diseases caused by thread-like parasitic round worms (nematodes) and their larvae. The larvae transmit the disease to humans through a mosquito bite. Filariasis is characterized by fever, chills, headache, and skin lesions in the early stages and, if untreated, can progress to include gross enlargement of the limbs and genitalia in a condition called elephantiasis. Approximately 170 million people in the tropical and subtropical areas of southeast Asia, South America, Africa, and the islands of the Pacific are affected by this debilitating parasitic disease. Filariasis is occasionally found in the United States, especially among immigrants from the Caribbean and Pacific islands. While filariasis is rarely fatal, it is the second leading cause of permanent and long-term disability in the world. The World Health Organization (WHO) has named filariasis one of only six "potentially eradicable" infectious diseases. In all cases, a mosquito bites an...