Wuchereria bancrofti, is a mosquito-transmitted parasite that causes deforming lymphatic filariasis in the tropics. Improved treatment methods have led to new thinking that it should be possible to interrupt transmission and eliminate this major public health problem by repeated, annual cycles of mass treatment with new single dose combination drug regimens. Egyptian villages involved in the study will be surveyed. Household members above 4 years of age will be tested for filariasis. Also, children in the first year classes of primary schools (5 to 6 years of age) will be tested for parasite infection. Village populations will be treated for filariasis as part of the MOH national filariasis elimination program. Children under age 5, pregnant women, and people with severe underlying illness are excluded from the program.