Lymphatic filariasis due to infection with Wuchereria bancrofti was introduced into the Americas with the importation of infected African slaves. In the early 1900s, both asymptomatic microfilaremia and the most obvious stigma of lymphatic filariasis, elephantiasis, were present in residents of Charleston, South Carolina.1 Although lymphatic filariasis never became endemic in the United States, filarial diseases remain a major health problem in many areas of the world. More than 90 million people are infected with lymphatic filarial parasites, and more than 900 million people living in areas of endemic infection are at risk.2 Filarial parasites are multicellular helminthic organisms belonging . . .