RESUMO
A Ficoll-Hypaque gradient centrifugation technique was used for isolation and concentration of microfilaria from peripheral blood of 30 subjects with clinically and parasitologically diagnosed Wuchereria bancrofti infections. 86% of the microfilaria were found in the Ficoll-Hypaque layer. None were detected in the plasma, leucocyte layer or lower erythrocyte layer. 14% of microfilaria were identified on the top part of the erythrocyte layer. A 35-fold concentration and 88% quantitative recovery of parasites was achieved by conventional centrifugation of microfilaria-rich Ficoll-Hypaque layer. Following the centrifugation procedures, living motile microfilaria were separated. These results indicated that Ficoll- Hypaque centrifugation technique could be an effective method for the detection of low levels of microfilaremia, and for obtaining relatively pure suspensions of living microfilaria for metabolic studies, production of antigen-rich excretory-secretory products and antigen analysis