This test is used to identify microfilariae, a filarial larva found in infected mosquitoes, in the blood. Lymphatic filariasis is the medical term for the disorder when microfilariae interfere with the lymphatic systems ability to function. A blood sample should be taken at night because they circulate in the body then. This test finds blood that has higher-than-normal antifilarial IgG4 antibody levels. Grossly swollen limbs, skin pitting, and even vaginal edoema are signs of the illness in situations of acute infection